Mammals – Discover-Nature

Red Panda

The red panda, Ailurus fulgens, a small mammal closely related to weasels and raccoons, is found in the Himalayan and Tibetan mountain ranges of Nepal, Bhutan, and southern China. There are two subspecies, the Himalayan red panda and the Chinese red panda, differentiated by slight skull and color variations. They were isolated almost 200,000 years ago by glaciation in the Brahmaputra River Valley.

Red pandas live in steeply sloped, heavily forested areas where bamboo grows in dense thickets and there is easy access to water. Their habitat ranges in altitude from 6,500 feet to over 14,000 feet, in a temperate area with average temperatures in the upper sixties (Fahrenheit). These mountain ranges contain many protected pockets of forest, interconnected with wildlife corridors through unprotected country. Some areas overlap habitat where the Giant Panda lives, and the two species must share the bamboo in these locations.

_{Red panda, Ailurus fulgens, by Pixabay 27707, Sep 2015}

_{Red panda, Ailurus fulgrens, climbing at Taronga Zoo, by Charles Wong}

The red panda has a round head with a short snout and white fringed, triangular ears. Adults are 24″ long and weigh about 15 pounds. Their fur is dense, reddish-brown and covered with dark guard hairs. A black belly and legs, with a white muzzle and alternating red and buff rings along an 18″ tail, ensures that the red panda is well camouflaged in a forested area covered in red moss and white lichen. They have five curved claws on each foot that can be partially retracted in addition to flexible joints in their pelvis and hind limbs and an elongated wrist bone ending in a false thumb. All of these adaptations allow for a great range of motion when climbing and moving about the forest.

_{Red panda, Ailurus fulgens, mom and newborn by Rainer Halama, Jul 2013}

Red panda, Ailurus fulgens, twittering

The red panda lives in solitude, except during mating season in late winter when they cautiously seek out mates, resting and feeding near one another for short periods. Mating occurs on the ground, and gestation lasts 13 weeks, but can be prolonged up to 24 weeks at the discretion of the mother. The female selects a den site, building a nest of sticks, leaves, grass, and moss. Litters are between 1 and 4 babies weighing only 3 to 4 ounces at birth. Babies are born covered in fur for warmth, but blind for their first 18 days. They depend on their mother for everything for three to five months, and will not leave home until a year has passed.

_{Red panda, Ailurus fulgrens, sunbathing by Su-May, Sep 2011}

_{Red panda, Ailurus fulgrens, Conservation of energy by Tina R Tiller}

Red pandas move easily through the trees as well as over open ground. Trees next to bamboo stands provide places to sit higher up and eat, but the forest also provides shelter, an escape route from potential predators, and branches to sunbathe on in colder weather. If temperatures become too bitter, red pandas can lower their metabolic rates, curl into a tight ball, and sleep for a few hours to conserve warmth and energy. Bamboo makes up a large part of their diet, but it is supplemented with fruits, flowers, eggs, small mammals and birds. They prefer to eat early in the morning and late in the afternoon, while intermittently sleeping during the remaining hours.

_{Chinese red panda, Ailurus fulgens, named Kinta at Nogeyama Zoo, by Toshihiro Gamo}

Red pandas are on the endangered species list with decreasing populations near 10,000 in the wild. Their primary predators include leopards and jackals, which they can escape from using their climbing skills and agility through rocky and forested areas. But their main threat comes from poachers who prize their fur and bushy tails for the hat making industry and habitat destruction and land development that is steadily cutting large forests into small, isolated acreages. Red pandas have been well studied and are a favorite species at many zoos. Consider getting out this year to see them and learn more at a zoo near you.

Squirrels of Illinois

Squirrels are members of the family Rodentia, along with about 40% of all mammals species including mice, rats, voles, beavers, muskrats, guinea pigs, and hamsters. Rodents are characterized by the two front teeth on both the upper and lower jaws that grow continuously their entire lives.

^{Note incisors on left strike against each other to remain sharp; Molars grow in back of mouth}

^{Rodent dental system by V. Leche, professor Stockholm hogskola}

^{Guinea pig incisors by Morbakka, Oct 2024}

Squirrels in Illinois can be found in forested areas as well as urban communities. They all use their long tails for balance when climbing trees or resting on branches as well as running along branches, wires, and tops of walls. Squirrels are excellent climbers and can jump up to ten feet. They are able to gnaw and chew through almost any non-metal material.

^{Grey squirrel jumping to a fence top by AJ, Nov 2017}

Most species are solitary dwellers, but not territorial, able to live on their own, but in close association with other squirrels, rarely fighting for territory, food, or mates. They breed twice each year, once in winter and once in early summer. Two to four young are typically born and can fend for themselves after about two months. The young will often stay with the mother until the next litter is born.

Squirrels use tree cavities for raising young and for protection from predators, but most of the time they live in nests built of twigs and leaves high up in a tree. Nests are normally located near readily available water. They eat a variety of foods including nuts, berries, acorns, fruit, buds, fungi, seeds, and insects.

^{Fox squirrel by Corey Seeman, Jan 2023}

^{Fox squirrel by Corey Seeman, Jan 2020}

The fox squirrel, Sciurus niger, is the largest species in Illinois at about 22″ in length and weighing up to two pounds. Their fur is reddish-brown, with lighter shades on ears, bellies, and tail edges. They are common in urban areas, but are often found where there are no gray squirrels. Fox squirrels are most active in the early morning and late evening and are excellent swimmers.

^{Grey squirrel by Zoblinski,}
^{Getty Images}

^{Leucistic (white) grey squirrel}
^{by Pete Weiler, Pexels}

^{Melinistic (black) grey squirrel}
^{by Tom GV, Getty Images}

The Eastern gray squirrel, Sciurus carolinensis, is slightly smaller at about 18″ long and weighs about a pound. They have short, gray fur, but are often subject to genetic variations that result in different colored fur. Common variants in Illinois include melanistic or black squirrels, leucistic or white squirrels, and albino squirrels. Eastern gray squirrels are abundant in urban areas and large forested tracks. However, there are very few forests left in Illinois to support these animals.

^{Red squirrel by Christopher Defalco, Pexels}

Red squirrels, Tamiasciurus hudsonicus, are small, about a foot long, weighing about a half pound. They have reddish-brown backs with white bellies and a dark orange stripe down their back in summertime. Red squirrels are found only in the northeast quarter of the state in large forested areas. They are diurnal, active in early morning and late evening.

^{Southern flying squirrel by EEI_Tony, Getty Images}

The Southern flying squirrel, Glaucomys volans, is the smallest species at about nine inches, weighing only two ounces. They have gray-red-brown backs with white bellies and are nocturnal, making them difficult to observe. Flying squirrels have large eyes to see better at night and a long, flattened tail that is used as a rudder when airborne. A flap of skin runs between the front and back legs on either side of their body and is stretched taut when their legs are spread, providing the ability to jump from a high place and glide down to a lower place. Unlike other squirrel species, flying squirrels share a communal nest during most of the year.

^{Northern flying squirrel by Dopeyden, Getty Images______While this is not the species found in Illinois, flight patterns are very similar…}

Squirrels play an important part in forest and urban tree regeneration. They bury acorns and other nuts in warmer months for winter food stores, but usually bury many more than they actually consume. The remainder are left to germinate, resulting in many new trees each year. Squirrels are fun to observe and can provide enjoyment and an opportunity to learn about wildlife behaviors. Come down to the Jurica-Suchy Nature Museum or a nature center near you to learn more about these amazing animals.

Greene Valley Trail

As the heat abated a little bit, we decided to take a hike at the DuPage County Greene Valley Forest Preserve in Naperville, Illinois, this past weekend. On the east side, in the central part of the preserve, a 2.25 mile trail loops from the south parking lot to the Southern DuPage County Regional Trail and the Valley Trail. Trails are well-marked, wide limestone paths, with plenty of room for walkers and bicycles.

We found a pleasant, open vista that was great for birdwatchers and prairie enthusiasts alike. The Valley Trail runs alongside the east branch of the DuPage River, which makes it attractive to bird species, although there is no view of the river for hikers. While it was an overcast day making bird identification difficult, we were able to observe those seen below:

^{Birds pictured above in clockwise order: Northern cardinal, Cardinalis cardinalis, by Mshake, Getty Images; Red-winged blackbird, Agelaius phoeniceus, by Robert Jakubowski, Pexels; Song sparrow, Melospiza melodia, by BrianEKushner, Getty Images; Common yellowthroat, Geothlypis trichas, by BrianEKushner, Getty Images; Field sparrow, Spizella pusilla, by Mr Jamsey, Getty Images Signature; Gray catbird, Dumetella carolinensis, by SKHoward, Getty Images Signature}

Vegetation varies greatly, providing good protection for many of the small mammals plus lots of perches for birds. Many plant varieties could be seen and identified without leaving the trails, including those pictured below.

Black raspberry, Rubus occidentalis; Edible in season
Climbing prairie rose, Rosa setigera; Pollinator species for bees
Common milkweed, Asclepias syriaca; Pollinator species supporting more than 450 species of insects
Cup plant, Silphium perfoliatum; Leaf wraps around the stem forming a water holding cup
Eastern Black Walnut, Juglans nigra; It is allelopathic, releasing chemicals from its roots that may give the tree some advantage over its nearest competitors for food and nutrients
Elderberry, Sambucus sp.; Sambucus is Greek for an ancient wind instrument sounding as a whistle
Grey headed coneflower, Ratibida pinnata; Perennial attractive to Butterflies & birds
Hemp dogbane, Apocynum cannabinum; All parts of the plant are toxic, possibly fatal
Joe Pye weed, Eutrochium sp; Considered medicinal by early American cultures
Northern red oak, Quercus rubra; Acorns need a minimum 3-month exposure to near freezing temperatures to germinate
Sumac, Rhus sp.; Prized as a spice from the cashew & mango tree families
Virginia creeper, Parthenocissus quinquefolia; Flowering vine in the grape family
Grey poplar, Populus x canescens; Cross between white poplar and Aspen
Wild bergamot, Monarda fistulosa; Considered medicinal in use as a tea for colds

^{Scroll through pictures above using the left & right arrows}

The area supported plenty of small mammals such as rabbit, shrew, deer, coyote, and both gray and fox squirrels. We saw lots of pollinators including bees, moths, butterflies, and dragonflies. Greene Valley Forest Preserve offers a wide range of hiking trails, a scenic overlook, camping and picnicking facilities, a model airplane field, and many events, including night sky observations throughout the year. Consider catching some of the amazing sights in natural areas near you.

^{Fauna pictured above in clockwise order: Coyote, Canis latrans, by Esteban Arango, pexels; Galls on grape leaves; White-tailed deer, Odocoileus virginianus, by Stefonlinton, Getty Images Signature; White cabbage butterfly, Pieris rapae, by Bejan Adrian, Pexels; Shrew by CreativeNature_nl, Getty Images; Eastern cottontail, Sylvilagus floridanus, by Brian Forsyth, Pexels}

White, Yellow, Green?

Polar bears, Ursus maritimus, live in the Arctic and are heavily dependent on the ice floes where they hunt, breed, and spend a majority of their lives, making them the only bear to be classified as a marine mammal. They are strong swimmers and are able to maintain a steady 6 mph swim speed for several hours, crossing long distances between ice floes. Polar bears are a relatively new species, having branched off from the brown bear family about 150,000 years ago. Their close family relationship enables them to breed with brown bears, and grizzly / polar bear cubs have been observed, although not often.

^{Polar bear, Ursus maritimus, walking on}
^{sea ice by vladsilver, Getty Images Pro}

^{Polar bear, Ursus maritimus, swimming in}
^{Arctic Ocean by FrankHildebrand, Getty Images Signature}

Many other marine animals inhabit the world of ice including the polar bear’s favorite prey: seals coming out of the water over the edge of an ice floe. Bears often wait at these locations for a chance to grab a seal with heavy, sharp claws. But seals are wary and slippery, and bears do not often capture them, losing 9 out of every 10 they hunt. Their white fur should help to conceal them against a background of snow and ice. But as you look at the following pictures, are they really white or yellow or tan or even green?

^{Polar bear in white by}
^{dagsjo, Getty Images Signature}

^{Polar bear in yellow by}
^{ekvals, Getty Images Signature}

^{Polar bear in green by}
^{Asten, Sep 2006}

A polar bear’s fur has a top layer of guard hairs and a bottom layer called the undercoat. Guard hairs are much longer and completely cover the undercoat. Both hair types are transparent with no pigment of any color. The guard hairs are hollow tubes filled with air that scatter visible light into all the different wavelengths of the spectrum. When we see a structure scattering light, it appears to be white. However, polar bears rarely look completely white, except in the spring after their annual molt when they shed their old fur and grow a new coat.

Most of the time, polar bear coats are shades of yellow or tan, possibly with some darker colors. Oils rubbed off from their prey, including fat from seal and whale bodies, tinge the fur in shades of light yellow or tan. When they are on land, constant contact with dirt and other environmental elements may add darker colors to their fur. Polar bears work hard to keep their fur clean and in good condition. When combined with a thick layer of fat on the inside of their skin, it is the best insulation against the outside environment where they live. Clean fur also provides good camouflage when stalking prey. They may roll in snow or wash off in the ocean to clean their fur.

^{Rolling in the snow by webguzs, Getty Images}

Bears that live in captivity, outside the Arctic, may display shades of green in their fur. Algae growing in warmer waters of captive environments gets inside the guard hair tubes, which make an ideal environment for it to grow. Neither saltwater nor extremely cold water, both found in Arctic environments, support the growth of algae. A long soak in saltwater is a popular restorative cure for bears in zoos.

^{Polar bear bathing at the zoo by iSailorr, Getty Images}

Come to see our polar bear at the Jurica-Suchy Nature Museum to learn more fascinating facts about this iconic species. For information or to make a reservation, please click here: Visit JSNM

Sounds of Spring

Thunder and heavy rain, soft rain and light wind, birds in the early morning, frogs in the evening, and maybe a coyote howl deep into the night are some of the sounds of spring. As cold temperatures ease into summer highs, walks through natural areas tend to be filled with many sights as well as opportunities to learn by being quiet and listening closely.

Calls and songs are used by many species for a variety of purposes. Thousands of birds are migrating through the area, especially on clear evenings, and calls help to keep birds together and establish who is the flight leader. Year-round species are re-establishing territories, using calls to warn intruders to stay away or warn family members of approaching threats. Frog species in particular are calling during evenings to find a mate, lay eggs, and begin the establishment of the next generation.

There are dozens of species active at this time of year, and as we have been taking nature walks on campus the last few days, here are some of the wildlife we are listening to (click on each picture to hear their call)…

^{Yellow-rumped warbler, Setophaga coronata, Mirceax, Getty Images}

Yellow-rumped warbler, Setophaga coronata, by Valerie Heemstra, 2024

^{Red-winged blackbird, Agelaius phoeniceus, by KenCanning, Getty Images Signature}

Red-winged blackbird, Agelaius phoeniceus, by Thomas Ryder Payne, 2022

^{Palm warbler, Setophaga palmarum, by Irving A. Gaffney, Getty Images}

Palm warbler, Setophaga palmarum, by Christopher McPherson, 2021

^{Northern waterthrush, Parkesia noveboracensis, by Carol Hamilton, Getty Images}

Northern waterthrush, Parkesia noveboracensis, by Lance A.M. Benner2017

^{Northern Parula, Setophaga americana, by Neil Bowman, Getty Images}

Northern Parula, Setophaga americana, by Richard E. Webster, 2023

^{Chipping sparrow, Spizella passerina, by Irving A. Gaffney, Getty Images}

Chipping sparrow, Spizella passerina, by David Tattersley, 2023

^{Blue-headed vireo, Vireo solitarius, Mirceax, Getty Images}

Blue-headed vireo, Vireo solitarius, by Thomas Magarian, 2024

^{Blue Jay, Cyanocitta cristata, by Miguel Opacic, Getty Images}

Blue Jay, Cyanocitta cristata, Sue Riffe, 2024

Bird songs have a structure and rhythm, and are repeated often to attract a mate, ward off rivals, or bond with a family member. Other calls give warning that danger is near, keep flocks together in flight, or create a pair bond, often between mother and chick.

Frogs and toads are mating and laying eggs in area ponds. Each species has its own distinctive call, used by the males to attract a mate, warn of potential danger, establish a territory, or to signal distress. Frog species being heard around campus at this time include the following (click on each picture to hear their call)…

^{American Toad, Anaxyrus americanus, by Mshake, Getty Images}

American Toad, Anaxyrus americanus, by Thomas Margarian, 2024

^{Boreal chorus frog, Pseudacris maculata, by Derwyn, Getty Images}

Boreal chorus frog, Pseudacris maculata, by Thomas Margarian, 2016

^{Spring peeper, Pseudacris crucifer by HuntImages, Getty Images Signature}

Spring peeper, Pseudacris crucifer by Paul Marvin, 2012

^{Northern Leopard Frog, Lithobates pipiens, by Jennifer Seeman, Getty Images}

Northern Leopard Frog, Lithobates pipiens, by Paul Marvin, 2015

Sometimes, coyote can be heard when walking in woodlands around campus late in the evening. There are a lot of different calls used by these canines to provide information to other individuals. You can listen below to a bark used to indicate a threat, a social call establishing an individual’s location, a begging call from a young one, and a howl audible over long distances to announce one’s presence. Other calls may include a woof to signal a low intensity threat, a yip to claim territory, a growl to threaten another animal, and a whine or yelp to show subservience to a more dominant individual.

^{Coyote, Canis latrans, barking by TakenPix, Getty Images}

Coyote, Canis latrans, bark by Paul Marvin, 2018

^{Coyote, Canis latrans, begging, by Keith Szafranski, Getty Images Signature}

Coyote, Canis latrans, begging call by Matthew L. Brady, 2025

^{Coyote, Canis latrans, social interaction by Michel Viard, Getty Images}

Coyote, Canis latrans, social call by Flor Sangermano, 2023

^{Coyote, Canis latrans, howling, by Keith Szafranski, Getty Images Signature}

Coyote, Canis latrans, howl by Paul Marvin, 2012

Additional wildlife sounds can be heard on campus around Lake Benedictine or in nearby forest preserves. Get out for a walk and be sure to listen throughout the day for bird species, and into the evening hours for frogs, toads, and coyotes.

Fancy Hair

Hair is a structure that is unique to mammals, growing from small organs called follicles found just under the outer layer of skin. Hair can be modified into different forms providing insulation, camouflage, signaling, sensing movement, and for use in defense.

^{A scanning electron microscope image of human hair showing keratin layers, by CSIRO, Oct 2008}

The hair shaft extends above the surface of the skin. It is formed from layers of a protein called keratin. When bundled together, the layers form strong and hardened strands. There are more than 50 types of keratin that together form hair, nails, outer skin layers, claws, hooves, horns, plates, and baleen. Many keratin proteins are combined with varying amounts of an amino acid called cysteine, that provides additional strength and hardness. Let’s investigate some forms of hair that help keep mammals protected.

Left: Armadillo scutes encapsulating their body by DonArnold, 2025; upper right: Armadillo showing arrangement of scutes and plates covering their body by DonArnold, 2025; lower right: Southern three-banded Armadillo, rolled into a ball, by MiraianeDL, Getty Images

An armadillo has a tough shell encasing the sides and upper parts of its body. The shell is composed of solid pieces covering hips and shoulders and bony plates in between. The entire shell is covered with scutes, small scale-like structures made from hair flattened into a tough, leathery layer protecting the outside of the shell. The bands form a flexible pattern that allow the animal to move quickly with very few of the softer body parts exposed. The three-banded armadillo of South America can roll up into an almost impenetrable ball with only the scutes exposed.

^{Pangolin searching for ants by 2630ben, Getty Images}

^{Pangolin lies rolled into a ball by Khlongwangchao, Getty Images}

The pangolin looks similar to an armadillo, and although they are not related, they do possess similar features. Pangolins can also roll up into a tight ball. Their tail, covered with sharp-edged scutes can be left outside the ball and used to lash out against potential predators. However, being smaller animals, this form of defense provides almost no protection against their greatest threat – humans. They are the most trafficked mammal in the world, hunted for their meat which is served as a delicacy in many parts of the world. Their scutes are also in high demand by cultures for medicine and by leather goods industries.

Mammalian spines and quills are two other structures formed from hair. Quills have a hardened outer covering, and a soft, spongy core, and are found in porcupines, echidnas, and some rodents. Spines also have a hard outer covering of keratin, but consist of solid layers of hair inside. Both structures are generally straight and rigid, and may be sharply pointed, with or without a barb at the end.

Porcupines have quills with sharp tips and a backward facing barb near their ends. Porcupines cannot shoot a quill at an attacker, but if the attacker comes into contact with any of the quills, their sharp ends easily penetrate skin. Quills are brittle and often break off after being embedded, and the barb makes them difficult to remove, resulting in a painful experience for an aggressor that gets too close.

^{Hedgehog rolled into a ball by Tchara, Getty Images}

Hedgehogs are known for their spines, which are all the same length, not barbed, and do not come out easily. They are more like prickles, providing a pointed reminder to an aggressor not to get too close. A hedgehog can roll into a ball with all of the spines projecting outwards, making it very difficult to grab or bite the animal without being pricked any number of times.

^{Echidna, aka Spiny Anteater, by DonArnold, 2025}

At the Jurica-Suchy Nature Museum, you can learn about these defense tactics, as well as those of other species and how they provide for their own safety. Make a reservation to come see us by visiting our website at: https://ben.edu/campus-links/jurica-suchy-nature-museum/ (click on Register to Visit the Museum)

Bearing Up In Winter

American black bears, Ursus americanus, live in several habitats in North America including forests, beaches, and alpine regions. However, their diet, home range, and sleeping pattern are unique to each individual bear. Winter behavior is determined by temperature and available food in their immediate area.

Black bear on the shoreline on Vancouver Island, BC by Miharing, Getty Images Signature

Black bear in first snow by KenCanning, Getty Images Signature

Bears are omnivores, eating a variety of plants, insects, fish, small animals, carrion, and human garbage. In colder months, the lack of readily available food and falling temperatures drive bears into dens to hibernate until warmer temperatures return. Typical den sites include hollow logs, under tree root masses, and rocky crevices or caves. Black bears, especially in areas of the Smoky Mountains where extreme temperature drops do not occur, will make dens in tree cavities high off the ground. Bears are not true hibernators and may be awake or even leave the den on days with warmer temperatures.

Black bear in rock crevice den by
Nastasic, Getty Images Signature

Black bear den under root mass by
Blazer76, Getty Images

Once they move into a den, bears can lower their body temperature by eight to twelve degrees and burn body fat to satisfy all of their energy requirements. They do not eat, drink, urinate, or defecate while in the den, although they do wake occasionally to shift their resting position. Bears remain in hibernation while cold temperatures persist. In Alaska’s interior, this may be up to seven months, while in southern and coastal areas hibernation might last only two to three months. In late summer and fall, bears eat 50 to 80 pounds of food and add three to six pounds of fat each day in preparation for winter.

Black bears are solitary animals, coming together only in summer to mate, a bi-annual activity for adult females. Females are able to delay implantation of the fertilized eggs until after they are in the den for the winter. Cubs are born after eight weeks, in mid-winter. They weigh less than half-a-pound and are hairless and helpless. An average litter of one to three cubs will nurse from their mother for three to six months and will be nearly five pounds each as they emerge from the den in late spring. Cubs stay with mom for about 18 months, learning to fend for themselves, and will reach an average of 80 pounds by the end of their first year.

Black bear den with female and nursing cubs by National Park Service

Unless the bear is a pregnant female or the weather conditions are extreme, if there is food available, there is no need to hibernate. Zoo bears historically do not hibernate. However, many zoos are changing their practices by reducing meal sizes so their bears do enter hibernation for short periods. Studies show that this leads to fewer problems with overweight bears, and allows pregnant females the quiet time needed for cubs to develop naturally.

Black bear cubs in spring in Glacier Bay National Park by National Park Service

Black bear female nursing cubs by Alan D Wilson, 2010

Scientists are studying several health issues important to both bears and humans. Bears lose about 25% of their muscle mass during an extended hibernation, but emerge from the den with strong bones and good physical abilities. As humans become less active due to aging or other circumstances, they lose almost 60% of muscle and bone mass in the same period. Loss of bone mass, termed osteoporosis, accounts for over half of the bone fractures in adults over fifty years of age. Studies on how bears conserve and reuse proteins during hibernation, and use fat for energy, may provide insights into helping people to maintain their strength and health as they age or become less active.

At the Jurica-Suchy Nature Museum, you can learn more about black bears, grizzly bears, and polar bears.

Baleen Whales

There are over 90 species of whales roaming every ocean habitat. There are two broad classifications of whales, baleen whales and toothed whales. Baleen whales lack teeth. When they open their mouths, a membrane made of keratin, called baleen, stretches from the upper to the lower jaw. This allows water to flow through its porous structure while trapping fish and zooplankton, small sea creatures, by the mouthful. Toothed whales have actual teeth and they hunt fish, squid, and other animals of the sea.

^{Clockwise above- Baleen by Paigefalk, Getty Images Signature; Humpback whale (baleen) by Craig Lambert, Getty Images; Orca whale (toothed) by Schmid-Reportagen, Pixabay}

There are 15 species of baleen whales compared to 77 species of toothed whales. Baleen whales are generally larger, with the blue whale being the largest whale in our oceans. Most baleen whales are migratory, moving between cold, polar waters that support large populations of prey and warmer waters that they use for breeding. While warm water environments support less prey, they have fewer predators and other risks, allowing newborn youngsters to grow and learn to defend themselves before migrating back to richer feeding grounds.

Humpback mother & calf by Lauren Baer, Getty Images

Consider the Sei whale, one species of baleen whale from the Rorqual family that is known for their slender, pointed heads and fins. They are one of the smallest baleen whales, growing to about 40′ in length as an adult. Exact population numbers are not known, but it is estimated there are about 60,000 Sei whales worldwide. Each Sei whale eats about one ton (2,000 pounds) of food each day, including krill, fish, and squid. One ton holds close to a half million krill, a small crustacean weighing about 2 grams. The entire population of Sei whales alone is consuming roughly 20 billion krill or other small fish each day!

Group of Antarctic krill by Noyan Yilmaz

Baleen whale eating by Julian Allchin, Getty Images

Whales, hummingbirds, humans, frogs, and rabbits are all tetrapods, animals whose ancestors had legs. Nearly all of the bones in one species can be found in each of the others, a condition called homology. This is the result of divergent evolution where organisms from the same common ancestor evolve and accumulate differences, often resulting in an entirely new species. These differences are selected based on both biotic and abiotic factors in the habitat. Whales have the same shoulder-arm-hand structure inside their side fins as a human arm. While our hands and arms let us reach, grasp, and throw an object in the air, a whale’s fin delivers a powerful push through the water they live in.

Whale fin to human arm bone structure homology by DonArnold, 2024

^{Humpback pushing with fin by Yann-Hubert, Getty Images Pro; Human arm throwing a ball by South Agency, Getty Images Signature}

At the Jurica-Suchy Nature Museum, you can observe and learn more about homologous structure from our Sei whale / human arm skeleton comparison. Plus we have more to show you concerning whales and other marine species from around the world. Read more about whales on the following sites:

Oak Tree Habitat, pt.2

In the last blog, we discussed oak trees as a keystone species, substantially affecting the types and abundance of other species in their habitat. There are 400-500 species of oaks worldwide, supporting an extraordinary 2,300 wildlife species not including fungi, bacteria, and other microorganisms. Oak trees in all stages of life and death have numerous biotic relationships with wildlife.

^{Badger in tree cavity by Byrdyak, Getty Images||Golden millipede in Lagos by efeghali, Getty Images||Neanura springtail by Henrik_L, Getty Images||Pileated woodpecker in oak tree by mtruchon, Getty Images||Slug & rollie pollies by Sonya Kate Wilson, Getty Images||Wood Mouse in tree cavity by byjohn, Getty Images}

Fungi are often identified as attacking oak trees, but they can have very beneficial relationships. Fungi growing in the ground assist an oak tree in getting nitrogen, phosphorous, and other nutrients out of the soil, and in return get carbon and energy from the sugars in the tree’s sap. Oaks provide a place to live for over 700 species of lichens, plus uncounted liverworts and mosses. Lichens covering the oak’s surface help to keep them free of fungal infections and invasive insects. Liverworts and mosses help oaks to retain water and release it into the soil over a long period of time. As oak limbs fall and decay, water retention softens the wood providing food and habitat for decomposers.

Green moss on oak tree by tntemerson, Getty Images

Lichen & peat moss on oak by Sean Gardner, Getty Images

Fallen oak leaves are slow to decompose due to their tannin and lignin content, both preservative compounds. Leaf litter, composed of several layers of fallen leaves, becomes habitat for many millions of species including millipedes, springtails, woodlice, slugs, beetles, ants, and other organisms that feed on decaying plants. Through their activities, the creatures of the leaf litter help to return nutrients to the trees.

Oak forest leaf litter by Tina_C_Olsen, Getty Images

Acorns, with high amounts of fats, proteins, and carbohydrates, are one of the healthiest and most sought after foods in the woodland. White oaks, living between 200 and 300 years, will produce about 3 million acorns during their lifetime. Many bird species eat acorns, but oak trees enjoy a special relationship with blue jays, whose beaks are strong enough to pry an acorn open. In autumn, blue jays enjoy feeding on acorns, but also cache them for winter, burying several at a time under a few inches of soil in various locations up to a mile from the originating tree. Although blue jays cache large quantities of acorns, they can only remember and retrieve about 25% of them, allowing many new oak trees to grow and spread into new areas.

Blue jay with red oak acorn by mirceaux, Getty Images

Oak trees support 31 mammal species who consume acorns for food, use the tree for shelter, or use the surrounding habitat for hunting. Gray squirrels and red squirrels favor acorns in the autumn and throughout the winter from caches hidden in nearby locations. They remember far more cache locations than blue jays, but there are still uneaten acorns that will germinate in spring to start new trees. Acorns are also a favorite food for badger, deer, wild board, and wood mouse.

^{Gray squirrel eating acorn by viktor2013, Getty Images}

^{Red squirrel with acorn by Neil_Burton, Getty Images}

Oak trees offer shelter for many species. Squirrels often build their nests high up among the leaves that provide protection from weather and predators. Dead branches, especially those with cavities, may remain on the tree for many years, providing excellent roost sites for bats. Open limbs, leafed areas, and cavities all provide nest sites for a variety of birds. In addition, the many insects drawn to oak trees provide a ready source of food for all of these nesters. Humans have been acorn consumers for millennia. Raw acorns, high in tannin content, can be toxic in larger quantities; but, properly prepared, acorns are high in calories, vitamin C, starch, magnesium, calcium, phosphorous, and antioxidants. They have been a food staple in many cultures and can be found in the records of ancient Greeks, Iberians, Japanese, and English.

Oak trees have many direct and indirect relationships with insects, which we will explore in the next blog.

Rodents

Rodentia are the largest order of mammals in the world, encompassing over 40% of mammal species. A rodent is characterized by having two pairs of large front teeth, one pair in each of the upper and lower jaws. These are called incisors and are used for gnawing vegetation. They have no canine teeth, leaving a large gap between the four front teeth and their molars in the back of the mouth. Rodents can be found in all types of habitat everywhere in the world except Antarctica, New Zealand and a few oceanic islands.

Capybara, Hydrochoerus hydrochaeris, use calls to warn others of danger and to find their young including purring, barking, cackling, whistling, whining, grunting, and chattering.

^{Capybara by Dick Culbert, Gibsons, B.C. Canada, May 2014}

The largest rodent is the capybara, Hydrochoerus hydrochaeris, growing up to 140 pounds. But a majority of species are small animals, under 4 ounces, with bulky bodies, short limbs, and long tails. Compared to their overall size, the body’s surface area is large and contributes to a greater loss of heat than larger animals. To combat this, rodents create more body heat by being constantly active. They consume large quantities of food to meet high energy needs. Many species are active year-round, coming out during early morning and late evening hours to feed. Animals living in habitats with extreme temperatures may hibernate to escape the cold or estivate to escape the heat. These species conserve energy by adjusting their body temperatures to within a few degrees of the air temperature and slow other bodily functions, requiring less food and more rest.

North American beaver, Castor canadensis, hone their upper teeth into efficient biting tools and defensive weaponry.

North American beaver, *Castor canadensis,* by Steve, Washington D.C., Jul 2008

Incisors grow constantly their entire lives. The front surface is protected by a hard enamel shell. The back surface of the upper pair is soft and easily wears away from the constant rubbing of the lower teeth as vegetation is bitten off and chewed. This creates a chisel like edge on the top teeth that is an excellent cutting surface. Teeth are used to gnaw vegetation, dig burrows, and for defense, if attacked. If an animal does not gnaw enough vegetation, the growth rate of the teeth becomes greater than what is being worn away and health problems can develop leading to the inability to eat. This most often occurs in captive animals who are not provided with sufficient quantities of harder vegetation.

Fox squirrels, Sciurus niger, scamper up tree trunks, along branches, and are able to leap to nearby trees, in addition to being fast on the ground and good swimmers.

^{Fox squirrel, Sciurus niger, by Karly Tuminello, Jul 2020}

Food is mainly seeds, leaves, fruit and small invertebrates or insects. A internal structure called a caecum contains bacteria that assists in breaking down plant material into digestible form. Several rodents have eyes that protrude in a half dome from their head allowing them to see both ahead and behind. This wide field of vision allows the animal to easily detect predators. Their daytime eyesight is poor, but they can detect ultra-violet light, allowing excellent vision during twilight hours when they are most often active. Most rodents live in large social groups, but forage individually, using a wide variety of alarm calls to keep others informed when danger is near.

Naked mole-rats, Heterocephalus glaber, have strong jaws that use one-quarter of all the muscle tissue in their body.

^{Naked mole-rats, Heterocephalus glaber, by Roman Klementschitz, Wien, Dec 2003}

Humans often consider rodent species to be harmful pests. While they may carry bacteria and cause nuisance problems, they are also beneficial by eating weed seeds and insects, keeping populations of many pest species in check. Rodents are widely used in human culture as food, clothing, pets, and laboratory animals for research. Visit a museum or nature center to learn about the many fun facts of each family in this amazing group of animals.

Kangaroo rats, Dipodomys sp, hop to move around but can jump 6 to 9 feet, and they get all their water from the seeds they eat.

^{Kangaroo rat, Dipodomys, by U.S. Fish & Wildlife, Sep 2005}

Extinct & Endangered – pt.3

An endangered species is one that is likely to become extinct in the near future, either worldwide or locally in a known range. In some instances, these species may be saved through habitat conservation, breeding assistance, and education. This final installment on Extinct & Endangered will take a look at three species in North America that have benefited greatly from such efforts.

The Gila Monster, Heloderma suspectum, is the only venomous lizard native to the United States and is listed as near threatened. Their ranges are quite small, covering 700 to 3000 square feet. They spend most of their lives in underground burrows, and they are only regularly outside for a couple of hours each day during their mating season, from March to May. Gila monsters hunt small animals, and prey is eaten alive, head first. Venom is delivered through their saliva as the prey is chewed and acts to slow the prey’s reactions. While venom is not deadly to humans, it can cause swelling and severe pain.

^{Gila Monster, Heloderma suspectum by Erin Donalson, Getty Images}

^{Gila Monster, Heloderma suspectum by Shoemcfly, Getty Images}

Gila monsters pose no direct threat to humans, usually living in remote areas, but still have a fearsome reputation that contributes to illegal hunting of the species. They were the first venomous animal in the United States to get legal protection from being collected, killed, or sold. As development threatens areas where the Gila monster is found, conservationists are moving populations to preserves where there is minimal interactions with humans. Breeding numbers in the wild are still robust, although captive breeding efforts have been started in zoos across North America. Education and preservation of appropriate habitat has so far kept this species off the endangered lists.

The black-footed ferret, Mustela nigripes, is listed as endangered, but increasing in population. Their native range includes southern Canada and the northern United States, but habitat loss and disease have reduced populations to only a few hundred. They are a playful member of the weasel family, using several vocalizations for communication including barks, chattering, and chuckling. They are nocturnal and rarely seen in the daytime. Prairie dogs, hunted in underground burrows at night, are their exclusive food source.

^{Black-footed ferret, Mustela nigripes, portrait by Delecrouix, Getty Images Pro}

^{Black-footed ferret, Mustela nigripes, at prairie dog burrow by kahj19, Getty Images}

The species was declared extinct in the late 1960s until a dozen individuals were found in Wyoming in the early 1980s. Deliberate extermination of prairie dog colonies, because they are considered a nuisance species, has had a significant impact on black-footed ferret populations. Habitat protection and captive breeding programs have been successful at boosting population numbers. There are now about 300 black-footed ferrets living in Wyoming and other sites in the north central and southwestern United States where individuals have been released. Habitat loss and disease are still constant threats, and scientists estimate that about 3,000 individuals will be required to save the species from extinction.

The California Condor, Gymnogyps californianus, the largest bird in North America, formerly nested in caves in high cliff faces along the southern California coast until real estate development claimed all of their habitat. In the 1980s, as the last 34 birds were captured, the species was declared extinct in the wild.

^{California Condor, Gymnogyps californianus, tagged, in flight by OldFulica, Getty Images}

Condors are slow flyers, soaring in great circles, searching for carcasses of dead animals to eat. They eat until they are full, and can go about two weeks between meals. Juveniles may take several months to learn to fly and land gracefully, without crashing. Condors reach reproductive maturity at four to six years of age, and can live over fifty years. After mating, females lay only one egg, and mating may not take place every year.

^{California Condor, Gymnogyps californianus, Grand Canyon by Blewulis, Getty Images Pro}

Even with slow reproduction rates, efforts to expand the population by hand-rearing and re-introduction to unaffected habitat have resulted in close to 450 birds back in the wild in California, Utah, Arizona, and the Baja. Still listed as an endangered species, the California condor is making great progress in rebuilding its population.

^{California Condor, Gymnogyps californianus by DonArnold, Mar 2024}

^{Introduction to Extinct & Endangered at Jurica-Suchy Nature Museum by DonArnold, Mar 2024}

Extinct and endangered species can be found in every habitat and location worldwide. Many are being helped by direct action with hand-rearing and habitat protection. Indirect action through new laws, conservation support, and education has also had a positive effect. Many of these species are on display at various nature museums including the Jurica-Suchy Nature Museum. Plan a visit soon to learn more.

Extinct & Endangered – pt.2

The International Union for Conservation of Nature (IUCN) gathers data through research and field projects on all known species of plants and animals. They work to educate people on conserving nature and sustainably using natural resources. The IUCN publishes a document known as The Red List providing the conservation status of all species. There are nine possible levels including Least Concern, Near Threatened, Vulnerable, Endangered, Critically Endangered, Extinct in the Wild, Extinct, Data Deficient, and Not Evaluated.

An endangered species is one that is likely to become extinct in the near future, either world-wide or locally in a known range. Critically endangered species are at extreme risk of extinction in the immediate future. A species is vulnerable when its population and breeding numbers are at risk, but have a chance to improve. Several factors considered are the current population size, how fast the population has increased or decreased over a short period of time, whether breeding rates are high or low, and what threats exist from habitat loss, poaching, and invasive species.

^{Eskimo curlew, Numenius borealis, @ Field Museum of Natural History by James St. John, Oct 2014}

The Eskimo curlew, Numenius borealis, spends northern hemisphere summers breeding on the Alaskan and western Canadian tundra. As the weather turns colder, they migrate to Argentina by flying east to the Atlantic Ocean, and then south. Although nests are built on open ground, they are difficult to find and study. Food includes berries, insects, and snails, but incubation and rearing habits have never been clearly identified. During migration in the mid-1800s, populations would darken the skies as tens of millions of birds followed the warmer weather. Eskimo curlews were hunted on both continents year-round. If a bird was wounded, the other flock members would circle back, becoming additional targets for hunters. Development cuts up large breeding areas to smaller sections reducing food sources and enabling predators to severely impact populations. The species is listed as critically endangered, although there has not been a confirmed sighting since 1963.

^{Proboscis Monkey, Nasalis larvatus, by Chris Smallwood, Jul 2013}

^{Proboscis Monkey, Nasalis larvatus, female with young by Martha de Jong-Lantink, Jun 2020}

The proboscis monkey, Nasalis larvatus, another endangered species, is found mostly in the mangrove forests in Borneo; it is one of the largest monkeys native to Asia. Living in swamps and lowland areas along rivers, they are excellent tree climbers and swimmers, having the ability to swim underwater for short distances. Their large noses, smaller in females and upturned in juveniles, are thought to make their calls louder and more attractive to the opposite sex. They communicate through a variety of calls to signal alarm and threat warnings, and to keep infants and group members close. Rapid loss of habitat to logging and oil palm plantations, plus hunting for their meat, considered a delicacy in some areas, have reduced populations by more than half in the last fifty years.

^{Whooping Crane, Grus americana, by Trish Gussler, May 2018; Whooping Crane, Grus americana, by Diana Robinson, Mar 2018; Whooping Crane, Grus americana, by Evangelio Gonzalez, Dec 2018}

The whooping crane, Grus americana, is one of only two crane species native to North America, and it remains on the list of endangered species although it may be starting a comeback. Birds build a nest on a slight rise in a marsh where one or two eggs are laid. Normally only one egg survives, and the juvenile stays with the parents for six to eight months. Populations were never large, but prior to European settlement, there were an estimated 10,000 birds. Hunting for meat and feathers, in addition to predation and habitat loss, drastically reduced population size from the mid 1800s to the early 1900s. Through several programs of captive breeding, wetland management, and extensive efforts to assist the juveniles in learning migration routes by following ultralight aircraft, populations have rebounded to about 600 today.

^{JSNM Extinct Endangered display; JSNM Eskimo curlew, Numenius borealis; JSNM Proboscis monkey face, Nasalis larvatus; JSNM Proboscis monkey, Nasalis larvatus; all pictures by DonArnold, Feb 2024}

In the final blog on this topic, we will take a look at a few success stories – species that have recovered with populations that continue to get stronger. Many nature museums have information and extinct species on display to learn from. All of the above species, and more, can be found at the Jurica-Suchy Nature Museum, so please stop by, or visit a local nature museum where you live.

Weasels

Weasels are members of the Mustelidae family, a group of carnivores that also includes badgers, otters, ferrets, martens, minks, and wolverines. All species have long necks and bodies with short legs, small, round ears, and thick fur. They are solitary animals that are active year-round, mostly at night. They use strong smelling scents from anal glands to mark their territory and signal other individuals when seeking a mate.

^{Clockwise: Black-footed ferret, Mustela nigripes, by J. Michael Lockhart, USFWS, Dec 2010; American mink, Neogale vison, by Patrick Reijnders; Common badger, Meles meles meles, by Prosthetic Head, Jun 2010; Wolverine, Gulo gulo, by National Park Service, 1968; Pine marten, Martes martes, by John Surrey, May 2015; Eurasian otter, Lutra lutra, by Bernard Landgraf, Jan 2005}

There are five species of weasels native to the Americas. Short-tailed weasels, also-known-as stoats, Mustela erminea and least weasels, Mustela nivalis, are found in the Arctic regions of northern Canada and Alaska. The long-tailed weasel, Mustela frenata, ranges from southern Canada through most of the continental United States to Central America and the northern areas of South America. Two other species of weasels that live in northern and central South America include the Colombian weasel, Neogale felipei, and the Amazon weasel, Neogale africana. The odd species name for the Amazon weasel was first derived from a museum skeleton that had been mislabeled as originating in Africa.

^{Short-tailed weasel, Mustela erminea, summer coat by Steve Hillebrand, USFWS, Nov 2012}

^{Short-tailed weasel, Mustela erminea, winter coat by Steven Hint, Mar 2011}

In summer, weasels are sandy-brown on their backs with light colored bellies and black-tipped tails. Species found in far northern regions molt twice each year, when their fur, except for the tail, changes to white for the winter. They have small heads with long whiskers and small, rounded ears. Necks and bodies are long and slim with short legs. Weasels are found in a variety of habitats from farmland to forested areas, but are often located along an open water source such as streams, rivers, and estuaries. The Colombian weasel has partial webbing of its feet, suggesting a semi-aquatic lifestyle. Long-tailed weasels and Amazon weasels have been observed easily swimming in larger bodies of water.

With their elongated bodies, weasels are able to easily follow prey into burrows, as well as through paths under ground cover such as leaves, snow and ice. Weasels are carnivores, hunting small mammals, birds, insects, and crustaceans. They are generally nocturnal hunters with keen senses of smell and hearing, making them capable predators. The least weasel, with a body between five and ten inches in length, has more biting power than a lion or hyena. A rabbit, its favorite prey, is five to ten times the size and weight of a weasel, but the weasel easily dispatches its prey by gripping the back of the neck to break the spine and kill it. Weasels are excellent climbers, allowing them to pursue prey off the ground.

^{Least weasel, Mustela nivalis by Keven Law, Aug 2008}

^{Least weasel, Mustela nivalis, summer in Alaska by Cecil Sanders, Aug 2008}

Weasel dens are built in burrows abandoned by other animals. A nest of grass and leaves is lined with fur from their prey. Mustelids use a reproductive strategy called embryonic diapause, found in very few mammal species. After conception, the new embryo enters a phase where it remains dormant for a period of time before implanting itself in the uterine wall to begin growth and development. The gestation period can be extended up to a year until conditions are optimal for the survival of both the offspring and the mother. In long-tailed weasels mating takes place in mid to late summer, but babies are born the following spring, when temperatures are warmer and food resources are plentiful and readily available.

Weasels mate in mid to late summer, and young are born the following spring. Kits are blind and deaf for the first two to three weeks after being born, but grow quickly and are weaned between five and six weeks. In most species, both males and females are sexually active before the end of their first summer. In one species, the short-tailed weasel, living in northern areas with short summers, females are sexually mature at two to three weeks while still blind and deaf following birth. Most are sexually mated before they are weaned. Kits will leave the nest to claim their own territory before their first winter.

^{Long-tailed weasel, Mustela frenata, in Seattle Washington by Janis Coralee Leonhardi, Jun 2021}

Most species worldwide are listed as of least concern, with strong populations. An exception is the Colombian weasel, about which very little is known. The first live one was discovered by an amateur naturalist in 2011. There are fewer than a dozen documented animals living in riparian habitats in the cloud forests of Colombia above 5,000 feet. It is thought they are doing well, but too little is known of this relatively new species. The Jurica-Suchy Nature Museum or most local nature museums have wonderful displays of weasels and other members of the mustelid family for you to learn more.

Sei Whale

The sei (SAY) whale, Balaenoptera borealis, is the third largest rorqual, a group of large baleen whales that feed by straining food from the water. They live 50 to 70 years and grow up to 60 feet in length, weighing 100,000 pounds. They have bluish-gray backs, creamy bellies, a tall, hooked dorsal fin, and a large mouth with 200-400 baleen plates made of keratin. Their skin is often marked with a series of curvy healed scars made by “cookie-cutter” sharks which attach themselves to large species with suction-cup lips hiding sharp teeth that cut out a section of flesh about two inches in diameter to eat.

There are two types of whales, toothed whales and baleen whales which are considerably larger, but have no teeth. Toothed whales and other cetaceans including dolphins and porpoises, have one blowhole leading to the left nasal passage. Baleen whales have both nasal passages open as two blowholes to accommodate their huge size, allowing a much greater air exchange when surfacing. In all cetaceans, muscles are contracted to open a nasal plug in the blowhole allowing them to breathe. When underwater, the muscles are relaxed, blocking the blowhole and preventing the animal from breathing in water. Air sacs immediately below the blowholes allow for creation of long, loud, low-frequency calls within the hearing range of humans. Most calls last less than one second and sound levels are equivalent to standing next to a jack hammer, carrying long distances underwater.

Sei whales are found in temperate oceans around the world, but not in polar or tropical waters. The southern sub-species population is slightly larger than the northern one, and there is no evidence of interbreeding. Current population estimates place a total of 80,000 individuals world-wide, but sei whales prefer deep ocean waters and rarely come near land making placement of tracking devices and accurate estimates difficult. Tagging has been moderately successful, with many lost signals. It is known that they migrate annually, following the available prey and using prevailing currents to move quickly, but exact migration routes and breeding areas are not yet known.

Sei whale feeding by Allison Henry, NOAA

Sei whales generally travel alone or in small groups of up to six individuals. They are one of the fastest swimmers of all ocean species, attaining speeds up to 35mph for short distances. When feeding, they swim on their sides near the surface with one side of their huge mouths open taking in large amounts of water and straining out prey. Their favorite food is copepods, a tiny planktonic crustacean, but they will also consume krill, squid, and small schooling fish such as anchovies, sardines, and mackerel. They may make shallow dives to pursue schools of fish, quietly sinking below the surface; they can stay underwater for five to twenty minutes. Each whale consumes about 1,000 pounds of food daily.

Sei whale mother & calf, by Christin Khan, NOAA, Jun 2014

Sei whales reach sexual maturity between six and twelve years old, and a young adult is about 45 feet in length. Females are slightly larger than males. Gestation is 11 to 13 months, and each female mates once every two to three years. One calf is born in winter. A newborn is about fifteen feet in length and weighs 1500 pounds at birth. Calves remain with their mother for six to nine months before being weaned off its mother’s milk. Males are polygynous where one male has mating rights with several females.

Sei whales were overhunted in the mid-1960s for meat and oil after blue whale and fin whale populations were decimated in earlier years. They were added to the IUCN Red List as endangered in 1970. Their only natural predator is a pack of orcas. Massive die-offs have been recorded in the last fifty years, and evidence suggests the cause is red tides, a harmful algal bloom that severely depletes oxygen levels in large areas and may last for several weeks or months.

Other threats include entanglement in fishing gear, leading to whales dragging the gear for long distances, ultimately tiring them to a point where feeding and breeding are impossible. Climate change affecting ocean water temperatures and currents is altering prey distribution and availability resulting in less successful foraging. Opening more shipping lanes in polar regions along the edges of sei whale territory, another result of climate change, contributes to more vessel strikes. Shipping also increases ocean noise, making long-range communications for all species more difficult; however, the impacts from this on the sei whale population is not well understood.

The sei whale remains a species with more mystery than knowledge. You can learn more about cetaceans in general from your local natural history museum or come to the Jurica-Suchy Nature Museum at Benedictine University to see a full skeleton of a sei whale on display.

At The Waterhole

Last week, we discovered adaptations that allow elephants to deal with gravity and heat. Asian elephants live mostly in tropical forests that are warm from plenty of sunlight, although very little light reaches through the canopy to the forest floor. Rainfall may be intermittent, and shade-tolerant vegetation changes with a lack or an abundance of water. African savannas have lots of grasslands with a few trees and shrubs. They have distinct wet and dry periods, but grasses grow deep root systems that sustain them throughout the year. African woodlands are more open than Asian forests allowing a variety of trees and shrubs that grow well in full sunlight.

Elephants live in large groups, called herds, led by the strongest adult female. The herd members include all the females plus any males who not yet teenagers. The matriarch knows where to find food and water. She is aggressive when it comes to protecting the rest of the herd and is always the first to confront any threat. Males grow into bulls and will start to fight other males in their teen years. Once this aggression starts, the matriarch will kick the young bull out of the family. Bulls travel alone or together with other bulls, but it is a dangerous time for them because they do not have the support and knowledge of the matriarch for finding food and water.

_{^{The Herd by WLDavies, Getty Images Signature}}

Elephants are old enough to mate in their mid-teens. Pregnancy lasts 18-22 months, and each cow has a baby once every five years until they are in their forties. The herd is very social and several females take care of each calf. Water holes are places where the herd engages in many social activities. Elephants use water to drink, to swim and play in, and to bathe. However, bathing for an elephant means getting dirty, not clean. Elephants stir up the edges of a water hole to create mud to wallow in. Or they will cover themselves with water followed by dirt sprayed on their bodies with their trunks. Dried mud provides cooling from the sun and keeps biting insects away from tender skin. Elephants love water and bathe often, helping to keep skin moisturized.

Lovely mud by bucky_za, Getty Images Signature

Food eaten daily includes about 300 pounds of grass, tree bark, fruit, and other green vegetation. Elephants also need salt to supplement their diet. Their tongues are too short to lick anything not in their mouth, so they use their tusks to dig furrows in the ground and pile up soil and stones. Large stones can be placed into their mouth to lick salt from, and small stones are ground up by their huge molars. Food eaten daily includes about 300 pounds of grass, tree bark, fruit, and other green vegetation.

African elephants are larger than Asian elephants and males are larger than females in all species. Asian elephants average life span is about 80 years in the wild, while African elephants live only 60 years. They are excellent swimmers, often submerging their whole body underwater except for their trunks, which are used as snorkels to breathe. On land, they are slow moving, but can run short distances at better than 20 mph. They use many vocalizations to communicate such as grunts, rumbles, trumpets, screams, and purrs, and they can use their trunks to modulate sounds.

A thousand years ago, ivory was a hot commodity, and hunters exterminated elephants in North Africa. In the last century, after remaining populations were severely depleted by the late 1800s, many countries banned the trade of ivory. Elephants are recovering today, but poaching continues to be a serious threat. As more humans have moved into their native ranges, existing populations have to live in smaller areas. At their rate of food consumption, vegetation does not have enough time to grow back, and herds today are experiencing food shortages. Several conservation organizations are working to provide land for the establishment of wider ranges, care for orphaned elephants, and combat poaching.

You can see and learn more about these wondrous animals at your local zoo or natural history museum.

^{Clockwise above: African bush elephants by designerpoint, Pixabay; Masai Mara elephants by tankbmb, Getty Images; African elephant by Donvanstaden, Getty Images; Friends by cocoparisienne, Pixabay; Asian elephant by miharing, Getty Images}

A Big, Cool One

Elephants are the largest land mammals and they live in a variety of habitats in tropical and subtropical regions. Their native habitat is often savanna, grassland or forest although they can also be found in desert, swamp, and highlands. These areas get twelve hours of sunlight each day, with warm, daily temperatures averaging from the lower 70s to above 100˚F for animals living in the desert. Heat and gravity are two natural factors that affect all large animals, and elephants have some unique methods and body design to compensate for both.

^{Walking in Kruger National Park by Simone Eman, simoneemanphotos}

Elephants have a massive skeleton with solid bones in their feet, legs, hips, and ribs that provide excellent support for all of their weight. Lots of muscles, both large and small, allow easy movement while still protecting their vital organs. But not all of the bones are solid. The skull is honeycombed throughout, so it is light enough that the neck can support the head and allow for many small and precise movements of the trunk, the ears, and the tusks. The brain is small for an animal of this size, but elephants are quick learners, have an excellent memory, and are one of the smartest animals.

^{Elephant’s foot by sboofek, Getty Images}

^{Elephants foot tread by skynavin, Getty Images}

While small animals, such as ants, can hang on to a vertical surface, elephants require a solid set of legs to stand and walk on. They actually stand on the tips of their toes, located along the front edge of the foot. The center and back of the foot is one large pad behind and under the toes that cushions each step and helps to carry their weight. The large, round flat of the foot spreads the weight evenly over a larger area, and their soles have treads to provide traction on slippery or uneven surfaces.

^{Elephant ears by Harvey Sapir, Pexels}

Heat from the sun, and from the exertion of the muscles performing under the tremendous weight of the body, must be dissipated efficiently. This task is handled by the elephant’s ears, which are very large and very thin. Hundreds of blood vessels run through each ear close to the skin to radiate heat away from the body. The blood, now cooled, can be circulated throughout the body. Skin over the rest of the body is thicker, but there is little to no fat underneath, nor is there any fur or hair covering the outside to trap heat. The skin also has many wrinkles creating much more surface area than smooth skin, allowing more heat to be lost to cooler air and water.

^{Celery anyone…by eugen_z, Getty Images}

An elephant’s trunk is a nose-arm-hand all wrapped into one. They can pick up large and heavy objects as well as being able to manipulate the sensitive tip to grab tiny and delicate objects. To help control the heat, they often will suck in a trunkful of water and using the end of the trunk like a shower head, spray all of the water across their body to wet down and cool off. Similarly, they can snuffle up a load of dust to spray across dry or wet skin to create a coating to help keep away biting insects and provide protection from the sun.

Elephants are built to move easily and efficiently in their environment, and they have several methods and adaptations to deal with their size and the heat. Next week we will discover more about family life and the lands they live in.

The Elephant Trunk

An elephant’s trunk is an amazing body part. It is a 300 pound nose-arm-hand about seven feet long. It contains 50,000 muscles, but no bones or cartilage, making it strong and flexible. A vast array of nerves controls it. Elephants use their trunks for a variety of tasks including:
• smelling an approaching rainstorm from 150 miles away
• locating food by smell including grass, branches, and fruit
• lifting objects up to 400 pounds
• reaching food 20 feet off the ground
• using it as a snorkel when swimming underwater
• using the top and bottom lip to pick up a single seed off the ground
• sucking up to 2.5 gallons of water and squirting it into their mouths
• sucking up water to squirt over their backs to cool off
• curling it around large quantities of food to place in their mouths
• controlling the shape and size of the nostril to modulate sounds
• snorting dirt to spray over their backs
• picking up and throwing objects in defense
• entwining with another’s trunk for a friendly hug

Sloths

Sloth, a word used in English for over 400 years to mean slow, was used in the 17th century to name six species of slow-moving mammals native to the tropical rainforests of Central America and northern South America. Those in the genus Choloepus have two toes on their forelimbs and include Linnaeus’s two-toed sloth, Choloepus didactylus, and Hoffman’s two-toed sloth, Choloepus hoffmanni. In a second genus, Bradypus, they have three toes on their forelimbs and include the pygmy three-toed sloth, Bradypus pygmaeus, the maned sloth, Bradypus torquatus, the pale-throated sloth, Bradypus tridactylus, and the brown-throated sloth, Bradypus variegatus.

^{Hoffmann’s two-toed sloth, Choloepus hoffmanni, by Leyo, Jul 2008}

^{Linnaeus’s two-toed sloth, Choloepus didactylus, at London Zoo by Dick Culbert, Nov 2007}

Sloths are 24″ to 30″ in length, weighing 8-17 pounds. They have rounded heads with tiny ears, and their forelimbs are almost twice as long as their hind limbs. Three-toed species have a small, stubby tail. Limbs are adapted for hanging and grasping, while strong claws help to support the weight of the animal. About half their body weight is from the undigested food in their stomach, which is constantly filled. Sloths have an unusual number of vertebrae in their necks, either six or nine compared to most mammal species that have seven. This allows them to almost look backwards, being able to turn through a 270˚ arc.

^{The most common sloth is the Brown-throated sloth, Bradypus variegatus, shown here in its native habitat at Cahuita National Park in southeast Costa Rica… by Christian Mehlführer, Feb 2007}

Everything about the sloth is slow: their daily routine, their feeding, their movements, and their metabolism. They are nocturnal, eating at night and spending most of the day hanging motionless, while sleeping. Their low-energy, leaf-based diet supports a slow-paced lifestyle. Sloths are primarily folivores, feeding on leaves and fruit of several tree species. They have a multi-chambered stomach with symbiotic bacteria to help digest fibrous vegetation in a slow process that can take several weeks to fully process a single meal.

^{Pale-throated sloth, Bradypus tridactylus, by Fernando Flores, Apr 2013}

^{Pygmy three-toed sloth, Bradypus pygmaeus, by Bernal Saborio, Jan 2017}

Sloths move very slowly, even when threatened, averaging just 13′ a minute. They rarely leave their arboreal habitat, except to defecate. This happens only once every eight days, when they go down to the ground. They are extremely awkward and exposed during these short periods. However, sloths are agile swimmers and often use this ability to move between locations. Having a low metabolism allows them to hold their breath underwater for up to 40 minutes. Slow movements also provide protection from predators that hunt by sight, looking for movement among the trees, including ocelots, jaguars, and harpy eagles.

^{Observe the tint of the green algae in the hair of this three-toed sloth, genus Bradypus, by HenryAlien, Aug 2008}

Sloths have long, shaggy hair that is home to a host of other organisms. Each strand is grooved, able to retain rain water, and hosts a symbiotic green algae. The algae gets shelter and water from the hair and provides nutrients to its host by absorption through the sloth’s skin. The algae is also a source of food for several other species including mosquitos, ticks, mites, beetles, and several moth species whose entire lifecycle depends on sloths. When a sloth goes down to the forest floor to defecate, female moths lay their eggs in the dung. Moth larvae feed and pupate in the dung, leaving several months later to fly up into the trees to find a mate in the sloth’s hair and begin a new cycle of life.

^{It is easy to imagine the grasping and defensive possibilities presented by these claws of Linnaeus’s two-toed sloth, Choloepus didactylus, by Andy, Dec 2018}

Sloths have several predators, but their long, sharp claws make formidable weapons if they are attacked. However, their biggest threats come from poaching, deforestation, and electric wires as more forest acreage is being opened to development. Habitat destruction is a serious threat to the world’s rainforests, and supporting efforts to slow down or stop this process provides the best assistance for sloths and other rainforest species. You can observe these unique and interesting animals at many zoos, or learn more at your local natural history museum, including the South American display at the Jurica-Suchy Nature Museum at Benedictine University.

Arctic Adaptations

The Arctic circle will experience its coldest time of year this month, as the sun does not rise in the visible sky between October and March. Animals that live in this part of the world have developed many adaptations for living easily and comfortably in these extreme conditions.

Most arctic animals are either very small or very large. Small animals, like arctic foxes and arctic hares, easily burrow under snow and ice to create comfortable dens. Tight entrances and long passages help keep air trapped under a thick layer of snow that acts as insulation, minimizing contact with the much colder external air. Body heat from the den’s occupants warms the temperature even further. Large animals also use dens including ringed seals and polar bears.

_{Polar bear on ice pack by Christopher Michel, Jul 2015; Musk Ox by Malcolm Manner, Mar 2013; Moose & frozen sagebrush by Steven Robinson, Oct 2017}

Larger animals have a high body volume to surface area ratio, as is found in the shape of a ball. Internal heat is generated relative to body volume, and it is lost relative to surface area. Large, tubby animals including polar bears, musk oxen, and moose generate lots of heat while losing very little. Other adaptations help maintain this balance of heat and loss.

Shaking polar bear by TambakoTheJaguar, Mar 2016

Thick, hollow fur/hair traps air inside each strand as well as underneath its heavy layers. Paws are covered in thick fur for stability, grip, and warmth. Long, furry tails can be used as blankets to wrap around bodies and noses. Oil secreted from special glands coat outer layers of fur, hair, feathers, and skin protecting the animal from direct contact with freezing waters. In addition, oil repels water so that it quickly runs off when the animal is on land, keeping them dryer and less exposed to cold air wicking away body heat.

Huddling fur seals by Michael Sale, Nov 2006

Huddling reindeer by Ben Townsend, Nov 2005

Polar bears, arctic foxes, walruses, seals, and musk oxen all have blubber, a thick accumulation of body fat just below the skin layer. This prevents cold from penetrating the body cavities that contain vital organs. It can also be utilized for energy for movement or to create additional body heat. Huddling is another method used to prevent cold from getting to the center of a mass. Used by musk oxen, arctic foxes, walruses, seals, and arctic hares, staying close with a large group is warm and comfortable.

Reindeer, also known as caribou, are known by their long noses. Air follows a twisty route through the nasal passage before reaching the lungs. Interior walls contain many blood vessels close to the surface that warm the passing air up to seventy degrees before it enters the lungs. Warm blood running through arteries from the heart distributes body heat. By the time it reaches an animal’s extremities, it has cooled and not much body heat can be lost. Reindeer have countercurrent vascular systems where veins containing cool blood returning to the body’s core run adjacent to arteries with warm blood. The colder veins absorb heat so the body core stays warmer.

Arctic fox staying warm by Marc Dumont, Feb 2015

Polar bear portrait by Peter Kaminski, Jan 2005

Extremities are one body area where heat is easily lost and exposure to cold can be damaging or deadly. Arctic foxes and arctic hares have shorter ears, noses, limbs, and snouts than species in the same families living in temperate weather zones. Ringed seals lack any external ears. Musk oxen have short legs and tiny ears, as do polar bears. Many of these adaptations can be viewed in the wild, or at your local zoo. Natural history museums also have displays where we can learn about many cold-adapted species.

Snow Leopards

Snow leopards, Panthera uncia, beautiful but shy cats, are one of the top predators in their high-altitude habitat. They are grey to white with large black spots covering their entire body, including the tail. A short muzzle and large nostrils help the snow leopard inhale large quantities of air in the thin atmosphere of their home range. Their bodies are short and stocky, ranging from 50 to 150 pounds. Snow leopards cannot roar, but have a wide range of calls including purring, meowing, grunting, moaning and chuffing.

Home ranges are generally large, covering from five square miles where vegetation and food are abundant to 150 square miles in sparser areas. Snow leopards are most active at dawn and dusk, resting near cliffs and ridges that provide shade and good vantage points for hunting. They are stealthy hunters and can actively pursue prey down mountainsides, dragging the kill to a safe location where they will consume all edible parts. Mainly carnivores, they feed on wild sheep, goats, ibex, and wild boar, but will hunt smaller prey including pika, marmot, and voles. They eat a large amount of supplemental vegetation such as grass and twigs. They prefer larger prey and can survive for two weeks on a wild sheep before needing to hunt again.

Panthera uncia, Snow leopard with kill by Shan Shul, Snow Leopard Trust

Snow leopards live in the alpine zones of central and southern Asia, from altitudes of 9,800′ to 14,800′. They have several adaptations for enduring the cold temperatures including small, round ears minimizing heat loss, fur on the bottoms of their paws to keep them warm while walking on snow and ice, large nostrils to heat and humidify the air they breathe, and a long, flexible tail used as a blanket for their face while sleeping.

Snow leopard, Panthera uncia, sleeping with tail blanket by Charles Barilleaux, Mar 2011

A snow leopard reaches sexual maturity between two and three years old. Their lifespan is 15 to 18 years in the wild, and may exceed 25 years in captivity. They are solitary cats, except when breeding in late winter. In late spring, two to three cubs are born blind and helpless, but with thick fur coats at birth. They can see at seven days and will be walking in five weeks. They leave the den for the first time in two to four months. They spend the first 18 months in the care of their mother learning to hunt and will establish their own territories before leaving permanently.

Panthera uncia, Learning to hunt by SLCF Mongolia, Snow Leopard Trust

Snow leopards are listed as vulnerable, with an estimated population of less than 10,000 remaining in the wild. The main threats to their survival are poaching for the illegal trade in fur and body parts and habitat destruction. Climate warming trends are causing 30% reductions in alpine zones worldwide, placing snow leopards in competition with predators from warmer habitats who are now able to range into higher altitudes.

Panthera uncia, Snow leopard cubs by Shan Shul, Snow Leopard Trust

The Global Snow Leopard Forum, World Wildlife Fund, the Snow Leopard Conservancy, and other groups are working with local people and countries to help snow leopards survive and to maintain the fragile environment they inhabit. Protected areas are being established in several countries that encompass their native ranges. These same areas provide food, resources, and some of the largest freshwater reservoirs on earth for the many species living there, including people.

Snow leopard, Panthera uncia, by Mark Dumont, Apr 2013

Snow leopards were first exhibited in 1872 by the Moscow Zoo. In 1990, at the Beijing Zoo, the first cat was bred in captivity. As temperatures cool down for the year, consider a trip to a zoo near you to see these wonderful cats.

Antlers & Horns

Antlers and horns, often referred to interchangeably, are sported by North American species in the deer and cattle families, respectively. Typically found only on males, except for caribou where both sexes grow antlers, there are distinct differences in growth and usage.

Elk at Rocky Mountain National Park by Michael Levine-Clark, Jul 2022

Bighorn sheep at Badlands National Park by Tim Lumley, Aug 2019

Antlers are found in the deer family, including white-tailed deer found across the continent, elk along the Pacific Coast and across the western U.S. – Canada border, caribou found in Alaska, mule deer located mainly in the western U.S., and moose found along the entire U.S. – Canada border. Horns are found on species in the bovine family including bison found in small herds across the grasslands west of the Mississippi River and sheep, goats and cattle found throughout the North American continent.

Caribou by Jacob W. Frank, Oct 2008; Elk by Scott Kinmartin, Jun 2009; Moose by Larry Lamsa, Aug 2021; Mule deer by Mark Moschell, Nov 2016; White-tailed deer by Jeff Bryant, Jan 2017

Antlers are shed at the conclusion of the breeding season each year, and a new pair is grown for the following year. Antlers grow from the tip, growing faster and larger as adults get older. Velvet, a layer of fine hair, covers the living bone and provides oxygen and nutrients to the developing antler. As annual breeding activities begin in late autumn, individuals will rub off the velvet and stop the bone from growing. After the breeding season ends in mid-winter, normal bone maintenance breaks down dead tissue at the base, and the antlers fall off.

Antlers are proudly displayed by males to attract mates and are a clear indicator of the bull’s health. Elk are the largest deer species, and a set of antlers may grow an inch a day, contain seven to eight points with a four foot spread, and weigh up to 20 pounds each. The largest elk bulls attract from five to thirty mates. Antlers are also used in defense of the herd and for asserting dominance over other herd members, typically for mates or food.

Horns are living bone on the inside, covered by a sheath of keratin composed of specialized hair follicles. Horns grow from the base where they meet the skull and grow continuously throughout the life of the animal. They are often curved in shape and covered with ridges or fluting.

Bighorn sheep by Renee Grayson, Aug 2018

Horns are used to establish dominance within a herd, marking those males that control the actions of the herd. They are used in defense of territory from individuals of other herds and as defensive weapons when interacting with predators. Horns are also used to dig roots for food and strip bark for marking territory.

As you walk the forest paths, keep watch for white-tailed deer growing their antlers at this time of year, and observe the transition as velvet is removed in the coming few months.

Pronghorns

…long distance champs, able to run at 30mph for 15 miles…

The pronghorn, Antilocapra americana, is the only living species in the family Antilocapridae. All of the animals in this family are native to North America, having diverged from a common ancestor in the giraffe family during the Early Miocene period about 14 million years ago. During the late 1800s, populations were estimated to be between 50 and 100 million animals, roaming from southern Canada to Arizona and eastern California to the Rocky Mountains. Fencing of land for ranching and farming severely impacted migration and breeding opportunities. These restrictions, along with hunting, reduced pronghorn populations to 20,000 by 1925. Establishing open range areas, including National Park land, and limiting hunting helped the pronghorn population grow back to about a half-million by the late 1900s.

Pronghorn female, white rump flash, Yellowstone National Park, WY by Ala

Pronghorns are deer-like mammals with bright white cheeks, bellies, and rumps against a reddish-tan body. Their short mane stands erect at 3″-4″ high. Bucks have a black neck patch and a broad black band running from their eyes to a black nose. Black horns grow to 12″ for females and up to 20″ on males, curving backward and inward with one prong jutting forward. Their eyes are large and set out from the skull allowing them to detect movement at distances of up to four miles. Teeth grow continuously in response to wear from eating rough grasses and brush. Pronghorns have hollow-core hairs covering their bodies. When the hair lies flat, it provides excellent insulation for colder temperatures. The hair can also stand erect, allowing cooler air to circulate next to the skin during summer heat.

Pronghorn female herd, Yellowstone National Park, WY by Elaine R. Wilson, 2008_fi

Pronghorns live in herds, a lifestyle that has several advantages for non-hunting animals living in flat, open terrain with large predators. Defense against predators is better when there are more pairs of eyes watching. More animals together in a herd also means there is the possibility of many fighting back against a predator. Herds keep males and females in closer contact at breeding time helping to synchronize mating cycles so that all young are born at the same time and can be cared for by many adults. Pronghorns warn distant herd members of predators by flaring long white hairs on rump patches that give a flash that is visible over long distances.

Pronghorn male, National Bison Range, MT by Alan D. Wilson, 2008_files

Dominant males establish territories early in the spring and defend these using loud snorts, chasing away competitors, and butting with their horns. Mating takes place in autumn, followed by seven months of gestation, with one or two fawns born in late spring. Newborn fawns lie quietly in tall grass, while mother feeds some distance away so as not to give away the fawn’s location to predators. She will visit each fawn several times a day to nurse. After 7-10 days, the fawns are strong enough to join the herd. Pronghorns are active night and day, catching snatches of sleep whenever possible while feeding. Herds migrate annually, following no set path, but going where food sources are available. While they avoid mud, rivers and streams are easily crossed as they are excellent swimmers.

Pronghorn male in full stride, Grand Teton National Park, WY by Alan D. Wil

Pronghorns are a unique native species of North America. The biggest threats to pronghorn today are oil exploration and strip mining as well as roads and fences across migration routes from spring breeding to winter grazing locations. They have the longest land migration of any species in the United States. Pronghorns are the second fastest animal on land, able to run at 70 mph for three to four minute bursts, while the cheetah is faster for short distances, pronghorns are the long distance champs, able to sustain 30 mph for distances in excess of 15 miles. You can see them at many zoos across the United States, or keep your eyes open as you travel their favorite range in southwestern Wyoming.

Giraffes

The giraffe, Giraffa camelopardalis, is the tallest animal in the world. Currently, it is classified as one species with nine subspecies, although taxonomists do not all agree on this. A group is properly called a “tower” of giraffes unless they are observed in motion, in which case we refer to them as a “journey” of giraffes. Giraffes have several interesting characteristics that we will explore.

Giraffe tower, Giraffa camelopardalis, by Richard Droker, 2014

Giraffes have a black prehensile tongue about 18″ long. The upper lip, also prehensile, in combination with the tongue, is used for grasping, holding, and pulling whole branches through their mouths to strip off all of the leaves and thorns. Their preferred food includes leaves, fruits, and flowers of woody species. The thorny acacia tree is a special favorite. Giraffes are ruminants, using strong stomach muscles to bring food back up to their mouths for chewing multiple times. For complete digestion, food makes its way through a giraffe’s four stomachs.

Giraffe, Giraffa camelopardalis, by Chester Zoo, 2009

Adult giraffes may reach heights of 14′ to 19′ and weigh from 1800 pounds to 2600 pounds. Their necks, up to eight feet long, have the same number of vertebrae as other mammals. As calves grow, cervical vertebrae grow longer. The neck is very long, yet too short to reach the ground, so a giraffe must spread and bend its front legs in order to drink. Giraffes do not need to drink more than once every few days, though, getting most of their water from their food.

Giraffe, Giraffa camelopardalis, by John Hilliard, 2010

A giraffe’s circulatory system includes several adaptations to accommodate its height. The heart is one of the largest muscles in the body at two feet long and weighing 25 pounds. It must generate almost twice the blood pressure of a human. With a resting heartbeat of 150 beats per minute, it pumps sixteen gallons of blood each minute. To prevent fainting, a network of veins and muscles along with several one-way valves, regulate blood flow, keeping it from rushing to or away from the head when it is lowered or raised. Giraffes have smaller red blood cells and many capillaries making oxygen absorption quicker to supply the energy needs of the muscles.

Giraffe, Giraffa camelopardalis, by Sergey Yeliseev, 2010

Giraffes sleep less than an hour each day, taking several short naps while standing. They give birth while standing and calves can stand and walk within an hour of being born. Their hooves, up to twelve inches in diameter, are made for comfortable walking and running. Adults can sprint short distances at 40 miles per hour or sustain a loping speed for several miles at 20-30 miles per hour. Their speed and size keeps adults safe from most predators, although calves are susceptible to lions, hyenas, leopards and wild dogs. Their normal life span is 25 years in the wild, but almost 50% of all calves are lost to predation before reaching adulthood.

Giraffe, Giraffa camelopardalis, by Bernard Spragg, 2012

Giraffes are listed as vulnerable on the IUCN Red List, with 90,000 individuals living in central and southern Africa, down from a population of 150,000 thirty years ago. The main threats are habitat loss and killing for the bushmeat market. As human populations expand, the need for firewood and livestock grazing areas results in shrinking forests and savannas. Another factor negatively impacting populations is climate change, including a severe drought across much of the central plains in 2017. Private game reserves and national parks offer protection, but they are limited in size and are being used by many species. Giraffes are vital to keeping ecosystems in balance, eating browse unreachable by other species, opening new areas, and promoting growth of grasses and brush for food for many smaller species.

Opossums

A marsupial is a mammal with young that are born not fully developed and are subsequently carried in a pouch on the abdomen of the mother where the young can attach to a teat and complete their development. The most well-known animals in this group are kangaroos, but we also have one species in Illinois, the Virginia opossum, Didelphis virginiana. The opossum is native to Illinois and is common in all parts of the state. The oldest remains found in Illinois date back 100,000 years ago, while worldwide, opossums are one of the oldest known mammals, with remains dating back about 20 million years ago to the Miocene period.

Virginia opossum, Didelphis virginiana by Phil Myers, UMAA 2008

An adult opossum has coarse gray hair covering its body with white facial hair and a long, pointed snout with a pink nose. They are about the size of a house cat with hairless ears and a one to two foot long hairless tail. Their tails are prehensile, adapted for seizing, grasping, or holding, and used for balancing and climbing. The hind feet have no claws, but do have an opposable toe used for climbing and grasping. They can appear fearsome when baring their teeth, having fifty of them, more than any other land mammal. They live in urban or edge habitats, finding shelter in old dens, rock crevices, hollow logs, and under wood or stone foundations.

Virginia opossum female with babies using tail for support, Didelphis virginiana by Dawn Pedersen, California Academy of Sciences SF

Females give birth to one or two litters each year, the first in mid-winter and a possible second litter in early spring. Young are born about two weeks after fertilization. A newborn, the size of a bumblebee, must crawl to the mother’s pouch where it will attach to a nipple and stay attached for two to three months to complete its development. Up to twenty young, called joeys, are born in each litter, but the female adult only has 13 teats and the remainder of the young do not survive. Young are weaned at about three months. Usually nocturnal and solitary animals, young will often strike out on their own but may return to the family group for the winter.

Virginia opossum adult, Didelphis virginiana by Phil Myers, UMAA

Opossum are omnivores eating a wide variety of food including fruit, grain, seeds, pet food, garbage, carrion, eggs, insects, frogs and other small animals. Ticks, found on many Illinois mammals, are a favorite food item. It is estimated that an adult opossum consumes several thousand annually. Opossum are scavengers, seed dispersers, and a control for small mammal and insect populations. In turn, they are prey for larger birds and mammals.

Virginia opossum juvenile, Didelphis virginiana by Lisa Wright 2007

When threatened, an opossum may respond by hissing, growling, baring its teeth, or playing dead. Playing dead, an autonomic response, occurs when the opossum faints. They lay on the ground with lips drawn back, teeth bared, eyes half or fully closed, saliva drooling, and a foul-smelling liquid excreted from their anal gland. Individuals can be poked, turned over or picked up and carried away with no response. They will recover by slowly regaining consciousness after several minutes or up to four hours. In the wild, their average life span is two years, and the leading cause of death is being hit by a vehicle.

Virginia opossum tail, Didelphis virginiana by Lisa Wright 2007

Opossum are protected under Illinois law as a furbearer. Hunting licenses are available each year with no limits. Permits may also be issued for nuisance animals that may be trapped for removal to another area. Adults are often infested with parasites, but carry none that are known to affect humans. They are rarely encountered or seen, but you may be able to observe them in the evening, especially under bird feeders or where pet food is left outside.

Beavers

Beavers, Castor canadensis, members of the order Rodentia, are mammals characterized by a single pair of continuously growing teeth located in each of the upper and lower jaws. Between three and three-and-a-half feet in length, beavers weigh 26 to 60 pounds. Their fur is reddish-brown with an outer layer of long, coarse guard hairs covering an inner layer of fine, short hair. Beavers often groom themselves and comb oil into their fur to make it waterproof, keeping the animal dry and warm. Their tails are covered with leathery scales and a few short hairs.

Castor canadensis, American beaver by Phil Myers, Museum of Zoology, UM-Ann Arbor

A beaver’s body, shaped like a bullet, is made for swimming with a top speed of 6-mph in the water. Their back feet have five toes with flexible webbing in between providing lots of power in the water, but making them rather clumsy and slow on land. Several other adaptations assist in making a beaver an incredible swimmer. Valves in their ears and nose can be closed to prevent water from entering. The eyes have a transparent eyelid that closes, protecting the eye, but allows them to still see underwater. Beavers can remain underwater for up to 15 minutes, covering a half-mile in distance. Upon diving, the heart rate slows by half, and the animal can tolerate a considerable amount of carbon dioxide buildup before requiring clean oxygen. They keep their front paws balled up in fists close to their heads to act as bumpers to push floating debris away, and their tail acts as a rudder.

Castor canadensis, American beaver by Tanya Dewey, American Diversity Web

Beavers live in colonies including a male and female who mate for life, their yearlings and new born kits. Kits mature in one-and-a-half to two years, and are then encouraged to move out on their own. Evidence of beaver activity in an area includes dams, gnawed trunks, paths and mudslides. Beavers make paths about a foot wide with trimmed edges and a brushed surface leading from their dwelling to feeding grounds. As paths become well used, they turn into mudslides when they lead into a pond. Usually roaming no more than a half mile from home, families will leave scent mounds of mud and bark mixed with anal gland secretions to mark their territories. When swimming, tails are used to send a warning by slapping the water. This not only creates a loud sound, but also can be used to generate a wave of water in the face of a potential predator allowing the beaver time to escape.

Path of Castor canadensis, American beaver by Tanya Dewey, American Diversity Web

Beavers are herbivores, and the plants they eat depend on what species are available in their home habitat. Woody species are an important food source during winter months, and are harvested in summer and fall to be cached in their dwelling or at the bottom of ponds near the dwelling entrance. These can then be accessed during winter months even if ponds are frozen over. Beavers are known to eat willow, river birch, maple, cottonwood, black cherry, dogwood, beech, and oak. They also eat roots and rhizomes of aquatic plants including water lilies, duckweed, arrowhead, and cattails, and will consume grasses, sedges, clovers, and corn on land. Beavers eat one-and-a-half to two pounds of food daily.

Bank dwelling of Castor canadensis, American beaver by Tanya Dewey, American Diversity Web

In the mid-to-late 1800s, beavers were extirpated in many localities by trapping for the fur trading industry. Reintroduced from neighboring colonies throughout the first half of the 1900s, beavers continue to fill an important role in the proper functioning of an ecosystem from blocking flowing water to create new wetlands to removing stands of trees and allowing new vegetation to colonize an area. New wetlands attract waterfowl, turtles, snakes, mammals, and insects. After several generations have cleared the surrounding land of trees and shrubs, beavers will move to a new area, allowing the abandoned homesite to slowly drain and fill in with new soils and opportunities for meadow flora and fauna.

Chipmunks

The eastern chipmunk, Tamias striatus, one of Illinois’ smaller mammals, is quite active in our area from late spring until mid-autumn. Chipmunks are abundant throughout Illinois, and they are one of four species of ground squirrels that also includes the thirteen-lined ground squirrel, the Franklin’s ground squirrel and the woodchuck. Chipmunks are the smallest of the four, weighing from two to five ounces and growing eight to twelve inches in length. They have alternating dark and light stripes on their backs, sides, and cheeks; light bellies; small, erect ears; and furry, flattened tails.

Eastern Chipmunk, Tamias striatus by Phil Myers, Museum of Zoology, University of Michigan-Ann Arbor

A chipmunk’s eyes are located on the sides of its head and provide excellent ninety-degree views from directly in front of their face around to both left and right sides. They can easily detect any nearby motion and moving shadows cast by birds or any other overhead object. Chipmunks have a poor sense of smell, but an excellent sense of hearing. They climb trees to escape predators and to search for food. Their fur is reddish-brown on top and a buff colored below, making them hard to see from overhead or underneath when they are up in the trees.

Eastern chipmunk burrow by Phil Myers, Museum of Zoology, University of Michigan-Ann Arbor

After finding a mate, chipmunks construct an underground nest of extensive tunnels and chambers using their noses and clawed feet. A work tunnel is started by digging a well-hidden entrance hole followed by a wider tunnel leading to a large, centrally located nest chamber lined with leaves. Several smaller chambers are dug for food storage. A second exit hole is handy for emergencies, and several tunnels extend downwards to draw water away from the main tunnel system. Nests are often re-used each winter, adding many tunnels and chambers through annual remodeling.

Mated chipmunks will enter their nest in mid-November and stay together underground until late March. Chipmunks do not accumulate bodily fat reserves and do not hibernate. They can reduce their metabolic rate by 85% during sleep periods lasting from three to seven days. Awake for one to two days between sleep periods, they restore energy by eating from cached food supplies. Mating occurs in early spring followed by a 31-day gestation period. Two to eight hairless and completely dependent young are born in late April. The male chipmunk may leave the nest in spring, leaving the female to handle all rearing of the young, which are weaned at about six weeks.

Eastern Chipmunk, Tamias striatus by J.P.Myers

Chipmunks have cheek pouches used for gathering food. These extend from the mouth down either side of the neck and are expandable, carrying up to two tablespoons of seeds and grass. Food may include seeds, nuts, fungi, bulbs, moles, grasshoppers, small frogs, salamanders, and bird eggs. Cheek pouches reduce the number of excursions outside the nest needed to fill food caches. However, they usually do not carry a maximum load because they still need to fit their head through their tunnel opening of about two inches in diameter. They find water in fallen leaves or small pools and will drink as much as 25% of their weight daily.

Chipmunks are common visitors to woodlands and backyards where food is easily found. When danger is nearby, they immediately freeze all movement and can hold their position for several minutes. When the tail is held upright, this is a signal of danger nearby. When establishing or defending territory, they will stomp their feet and swish their tails. Chipmunks take frequent dust baths to remove mites, fleas and other bugs from their fur. Active mainly in the early morning and late afternoon, they are fun to observe, especially when exhibiting their unique behaviors.

Oh To Be So Shrew-d

The most abundant mammal in Illinois and a frequent visitors to fields, forests and backyards is an animal that is almost never seen. Among the most primitive of animals, the Northern short-tailed shrew, Blarina brevicauda, is an insectivore, eating mainly insects. The shrew family contains 312 species worldwide of which 33 are native to North America. They are small mammals with short, dense fur, five-clawed toes and small eyes and ears. A wedge shaped skull ends in a long, pointed nose. An adult shrew is four inches in length plus a one inch tail and weighs about one ounce.

Masked Shrew, Sorex cinereus by Phil Myers, UMAA

The shrew is a secretive animal, staying hidden when above ground. They live mainly underground, digging tunnels or using old tunnels abandoned by voles. Their burrow entrances are marked by a glandular secretion that serves as a warning to keep other shrews away. A male and female usually mate for life, but meetings between other individuals most often result in combat. They are fierce competitors and will initially try to chase each other away. Combat is marked by much screeching with kicking and biting until one relents. Fights end when one combatant assumes a submissive position, laying on its back, and the other leaves. Rarely do fights end in death.

Northern short-tailed shrew, Blarina brevicauda by Marjorie OBrien

Breeding begins in early spring. Shrews can have two to three litters each year with five to ten young born in each litter. Nests are built from grass, leaves and hair and are located under logs or inside burrows. At birth, a young shrew is blind, pink, and hairless. Babies are the size of a honeybee. A baby shrew feeds on mother’s milk for about three weeks until it is able to fend for itself. A typical lifespan is one to two years.

Northern short-tailed shrew, Blarina brevicauda by Phil Myers, UMAA

Shrews can eat one-and-a-half times their weight each day. They eat several times every 24 hours and are active at all times of the day and night. They take short rest periods between meals, but no long sleep period. Shrews have poor hearing and eyesight and find their prey by smell and touch. Long runways are constructed underground, attracting beetle larvae, earthworms, snails and an occasional mouse. Unique among mammals, the Northern short-tailed shrew can paralyze a victim with venom contained in its saliva, and then save the prey for a later meal. They can deliver a painful bite to humans, but the venom will not harm us. Shrews live deep underground in winter, continuing to feed on dormant beetle adults and larvae throughout the season.

Three other shrews also live in Illinois but are much less abundant. These include the masked shrew, Sorex cinereus, found in wetland areas; the least shrew, Cryptotis parva, active at night in grassy fields; and the pygmy shrew, Sorex hoyi, found in deep woods. The pygmy shrew is thought to be very rare, but that may be because of its secretive nature and diminutive size, weighing about 1/16th of an ounce.

Northern short-tailed shrew, Blarina brevicauda by Gilles Gonthier

The shrew may be a difficult animal to observe, but it is an important link in the food chain. They maintain a healthy control on the insect populations where they live. In turn, they provide food for minks, hawks, owls and snakes. They are abundant and secretive, but if you want to observe their behaviors, one of the best places to start is to look under bird feeders in your backyard. Search for a small, two inch diameter hole where the shrew may be poking out its nose in search of falling seeds for a snack.

Squirrels

Excuse me! Your bird feeder is empty! That’s what the squirrels in my backyard tell me every other day. I have several feeders, some year round, and more in the winter months. Squirrels are alert, always wary of their surroundings, yet show very little fear of humans They are presumptuous, eager, intelligent, and fun to observe. Unique adaptations allow some to scurry up and down tree trunks, and others to fly.

Eastern Grey Squirrels, Sciurus carolinensis, seem to be everywhere, running up and down tree trunks, scampering across limbs, leaping from tree to tree, and planning new ways to get into the neighborhood bird feeders. They are active year-round and are diurnal, active early in the morning and late in the afternoon, often resting during the middle of the day, but, even while resting, they must be constantly alert for predators. Squirrels are shades of black and brown fur tipped with gray above with white bellies. When looking up into the trees, the lighter colored underside blends with the sky making it harder to see. For a predator flying overhead, the darker shades of the squirrel’s back blends in with the leaves, twigs and ground colors. At this time of year, activity increases as squirrels cut, drop and bury nuts for the winter. Each nut is buried separately under one to two inches of soil. Squirrels do not have to remember where they buried their food because of their excellent sense of smell. They can detect a buried nut from up to a foot away even through layers of soil. Grey squirrels will find and eat about 85% of their cached food each season.

Eastern Fox Squirrel, *Sciurus niger*, by DonArnold

The Eastern Fox Squirrel, Sciurus niger, is the largest squirrel in northern Illinois. It is similar in coloration to the Grey Squirrel, but with yellow undersides and no silver tipped hairs on its back. Although not considered a social species, several individuals may den together in the winter to maintain warmth. Fox Squirrels prefer winter dens in holes in trees, often using abandoned woodpecker holes. If there are no holes available, they will build a leaf nest with a side entrance hole and line it with grass, leaves, and moss. They also cache nuts for the winter, using tree cavities whenever possible. Fox Squirrels may have four to six active dens at any time, switching between them.

Red Squirrel, *Tamiasciurus hudsonicus*, by Robert Taylor, C-2012

The Red Squirrel, Tamiasciurus hudsonicus, sometimes known as Pine Squirrel or Chickaree, is our smallest squirrel, not often seen in DuPage County, which is on the southern edge of its range. Red Squirrels have rust-red to grey coats, brightest on their sides with white bellies. In winter, a black line separates the red from white on the body and carries through the tail with the black band edged in white. They are the most carnivorous of the species inhabiting this area bird eggs and young birds in addition to nuts, berries, and seeds. They cache pine cones for the winter. Red Squirrels also feed on sugar maple and red maple trees, chewing into the xylem under the bark to start a slow flow of sap. As the mixture of glucose and water oozes out, the squirrel will leave the patch to dry. As it leaves the tree, wet sap is about 2% sugar. As the water evaporates, the remaining mixture becomes almost 55% sugar, a high energy food.

Southern Flying Squirrel, *Glaucomys volans*, by Judy Frederick, C-2012

The last of our acrobats, the Southern Flying Squirrel, Glaucomys volans, has a silky coat, brown on the back and white on the belly, with an extra fold of skin between the forelegs and the hindlegs. This skin allows Flying Squirrels to glide from a high trunk to a lower one, traveling up to 80 yards in one leap. Their wide, flat tails are used as rudders to turn or change the angle of descent in mid-air. The tail also acts as an air brake, dropping to slow their descent as the forelegs are raised and the squirrel makes a soft landing. Although active only at night, they immediately move to the other side of the trunk on landing in case there are any predators – owls – following their flight through the trees. Flying Squirrels are agile climbers and gliders, but are clumsy on the ground, so they spend a majority of their time among the trees. They prefer to live in large, mature forested areas where trees are spaced far enough apart to allow gliding without obstacles. Preferred foods include nuts, berries, seeds and bird eggs. These ravenous squirrels may store as many as 15,000 nuts in one season.

Eastern Gray Squirrel heading down, by DonArnold

All squirrels move easily through the trees. They have sharp claws for climbing and hanging onto vertical tree trunks. Muscular legs allow them to jump between branches and from tree to tree. In winter, feet and toes are covered with hair for extra grip on slippery surfaces. Squirrels can go down a tree trunk head first, just as fast as they can go up, due to a unique adaptation that allows these animals to turn their paws 180˚ and provide just as much grip in either direction. When observing squirrels, note their tail movements. Tails are used for balance and communication, flicking movement indicates agitation from danger close by, and the faster the flick, the more dangerous the situation. Squirrels also use calls to communicate. A rapid kuk-kuk-kuk indicates immediate danger. As the danger passes, the call will slow down. Once the danger is gone, calls will stop and tails will be laid comfortably along backs.

Oak-hickory forests cover one fourth of all the forested areas east of the Mississippi River in the United States. Winds carry some seeds long distances, others encased in tasty fruits, will be eaten and dropped far from the plant they grew on. Acorns and nuts are relatively heavy, falling to the ground immediately underneath the parent trees. Squirrels and oaks have a wonderful relationship, where one gets food and shelter, and the other gets its offspring spread across the forest.

As forested areas are overtaken by human development, they are cut up into smaller and smaller islands of habitat. Many squirrels are well adapted to live in urban environments among humans and our dwellings. They can easily switch to different food groups including berries, seeds, fruit, mushrooms and nuts. All of these are plentiful in our gardens and bird feeders. An urban environment can support up to 20 squirrels per acre compared to a forested acre that supports only one to two individuals due to competition for food. Squirrels provide many ecological services from reforestation to providing a source of food for predators, as well as endless entertainment for us!

Hibernation

Days are getting shorter and temperatures are starting to cool. We are well into autumn, and it is time for animals to prepare for winter when it will become difficult for them to keep warm and find food. There are several approaches to living through winter: growing thicker fur coats, travelling south to follow the quickly retreating warmer temperatures, and sleeping in until warmer, sunlit mornings prevail. Animals that “sleep-in” are actually going through a period of dormancy. It can last from a few weeks to several months, but there are some general conditions that must be met. Almost all species will need a home that consistently stays above freezing, and each animal must have enough energy to last through the dormancy period. There are four categories of dormancy including hibernation, torpor, brumation, and diapause. Let’s take a look at these methods and some species that use each.

Hibernation is a process that involves a significantly lower body temperature, and decreased heart, respiration, and metabolic rates. Species that are true hibernators can live for long periods of time with very low energy use. Woodchucks, also known as groundhogs, hibernate up to five months each year in the northern areas of the eastern U.S. They have a normal heartbeat of 80 beats per minute which is reduced to about 5 beats per minute; their normal body temperature is reduced from 98°F to 38°F; and their breathing rate goes from 16 times per minute to twice a minute. The woodchuck also exhibits reductions in other growth areas including teeth, which normally grow 1/16″ weekly and are kept under control by the grinding action when they eat.

Eatern Chipmunk, *Tamias striatus*, by DonArnold, c-1999

Species are either obligate or facultative hibernators depending on when they enter a period of dormancy. Obligate hibernators use seasonal cues. When days start to shorten, indicating a change in season, these species will enter hibernation regardless of outside temperatures or amount of available food. Facultative hibernators use environmental cues. When it becomes too cold or food starts to become scarce, these species will enter hibernation to conserve on their energy use. All species that spend time in hibernation eat larger amounts of food in autumn to build up brown fat. These fat reserves provide the quick energy needed for activities upon awakening.

Species in hibernation may waken occasionally. Animals have been observed waking to use a toilet area and/or to nibble on cached food supplies. Chipmunks can be observed with fat cheeks in autumn, busily creating food caches located in burrows found under the frost line in the same area where their summer nest is located. Although this reason for waking is not well understood, one theory is that waking may stimulate energy use followed by the ability to sustain a longer sleep period. Another theory postulates that periodic eating of small amounts of food sustains the immune response system.

Torpor is a similar process that involves the same physical modifications as hibernation, but in smaller quantities. Body temperatures and heart rates will be lower by ten to fifteen percent, and animals using this strategy will wake more often, engaging in activities several times throughout the cold period. Skunks enter their dens as daytime temperatures sink below freezing, and their heart and respiration rates slow. Their sleep may last from a few days to a few weeks. They will leave the den to forage for food in between these naps. Many birds enter torpor on a daily basis, at night or on very cold days. Their decreased physiological activity allows them to conserve body fat overnight so it is available for quick energy production the following morning to continue daily foraging activities. On cold nights, black-capped chickadees can maintain body temperatures twelve degrees lower than normal. This allows the body to use 30% less stored fat.

Brumation is the term used for torpor in ectotherms. Ectotherms obtain their body heat from the environment and include reptiles, amphibians and fish. Most of these species must live where the temperatures always stay above freezing. Many frogs and turtles bury themselves in mud at the bottoms of ponds, or dig holes deep into the ground, well below the frostline. Their breathing and heart rate slow and they can get oxygen from air trapped in the cavity or surrounding mud. Snakes will often den together in groups of a dozen to several hundred individuals in a den below the frostline. The wood frog is an exception because it can tolerate freezing temperatures. A chemical contained in each cell in its body acts as antifreeze to protect the cell from damage that could be incurred if solid ice should form inside the body. Thirty five to forty five percent of the body may freeze, stopping the heart and respiration, but it will thaw with warming temperatures. The wood frog may freeze and thaw several times in one season. All ectotherms may wake on warmer days in mid-winter and leave their dens to find water and nutrients.

Yellow-Jacket Wasp by Dog-WalkDigital, c-2011

In late autumn, before temperatures turn cold, some insect species enter diapause, a period of suspended development. Some spend winter here in underground burrows, under bark or leaf litter, or in holes drilled into woody plants. Many have the same cellular chemistry as wood frogs, with each cell having a chemical antifreeze to prevent damage from ice formation. For bumblebees and yellow jacket wasps, only the new queens survive, spending the winter in an underground burrow until spring. Bees spend the longest time in any form of hibernation, often five to six months underground.

Strategies to survive cold periods are important as parts of the normal annual cycle. Zoos attempt to provide habitat that can accommodate these needs. Cold-adapted animals in northern climates remain outdoors for winter as part of a healthy life cycle. The risks involved with cold periods include the need to meet nutrient demands by storing fat or food caches, having energy in reserve to forage when warm weather arrives, and having enough water to hydrate throughout the cold period. Climate change and warm days in the middle of winter are another threat that is not easily quantifiable. Animals may wake and start to move about during warming episodes, but may not find any food available, wasting energy and water.

We can help by following some simple guidelines: leave animals and habitats undisturbed during cold months; offer food sources for animals during warmer periods (i.e. extra seed if temperatures get above freezing); learn more about the habitats in your neighborhood to protect them from disturbance and fragmentation and learn more about climate change and the negative effects caused by it. Here are a few books you may find interesting: “Animals That Hibernate”, a children’s pictorial by Larry Dane Brimner; “Do Not Disturb”, a children’s reader by Margery Facklam; “Winter World” by Heinrich Bernd.

Nocturnal Animals

I like to get outside every day, but with these really hot days oftentimes I go for a walk late in the evening as things start to cool off. It is quieter and pleasant – but not too quiet. There are still lots of sights and sounds of nature at night. What are all of these animals that are out well into the night? And why are they not active during the day? And how do they see in order to do anything?

All animals use their senses to find food and shelter and avoid predators. Nocturnal (active at night) animals have heightened senses or special adaptations that help them survive in the dark. Sight is the sense that humans rely on the most, but it is not as useful when there is very little light available. Structures in the eye called cones allow animals to see color. Other structures called rods are used to gather light. The more rods in the eye, the better an animal can see overall, and especially at night. Some nocturnal animals such as raccoons, bobcats, owls and rabbits have many more rods than daytime animals allowing them to see much clearer in the dark. And many of those same animals have very large pupils that let in more light.

Large eye pupils on Eastern Screech Owl,*Megascops asio* by Greg Hume

Owls, opossum, deer and fox have much better hearing than most other animals. Hearing adaptations include having larger ears, many of which are cup-shaped in order to gather more and fainter sound waves. A hertz (hz) is a unit of measure for soundwaves. We can hear between 20hz and 20,000hz, whereas a mouse can hear from 1,000hz to 100,000hz. This means the mouse can detect an insect moving under the leaves from several yards away. Another adaptation of many nocturnal species is asymmetrical ears. They can hear from each ear independently, allowing them to triangulate where the sound is originating. Triangulation can help identify the direction the sound is coming from – right, left, up or down, as well as how far away the point of origin is.

Echolocation, a specialized version of a hearing adaptation is used by bats in our area. The bat produces a high-pitched sound wave that is returned to the bat’s ears after it has bounced off another object. Bats use echolocation to determine an object’s size, shape, distance and whether the object is moving or stationary. If the object is moving, the bat can also determine the direction. A bat can emit calls at a slow rate of 15-20 per second up to 200 per second when closing in on prey.

Coyote, Yosemite 2009 by Yathin S Krishnappa

Smell is another sense used for hunting. Fox, raccoon, coyote, mink and skunk all have enhanced nasal passages and brain centers for detecting and identifying odors. They have enhanced abilities to detect fainter odors and to be able to identify their origin to a finer degree. Nighttime air is often still and moist, allowing scent molecules to linger longer, enabling an animal to better locate food as well as detect predators.

Two views of Wellington, New Zealand, taken same night by Science Learning Hub–Pokapū Akoranga Pūtaiao, University of Waikato, http://www.sciencelearn.org.nz

All of these differences make life easier at night for nocturnal species. There are fewer predators, and it is easier to hide in order to avoid becoming a meal. But there is also less competition with other predators to find food, and enhanced senses to create unique hunting strategies. Light pollution can be a huge negative influence on true nocturnal species. Constant night light sources affect species dependent on day-night triggers for behavioral patterns. Migration patterns may be disrupted; insects are attracted to light/heat sources only to be trapped and/or killed; reproductive cycles can be altered. In the green frog, an Illinois native, males will call less and move around more making it much harder for females to find and mate with them.

You can learn more by spending some time enjoying the nighttime yourself. Use your senses to detect what is active in your own backyard after dark. Try observing with and without a flashlight or your porch light. Give other species time to get comfortable with you being outside by spending 5-7 minutes sitting quietly before moving around. Use a cell phone to record what you are hearing, and write down your observations and experience as soon as you can after returning indoors. Consider repeating this activity on a rainy night or a winter night, and keep a journal of your experiences to learn and better understand the habitats where you live.

Bats

Myotis lucifugus, little brown bat, Myotis septentrionalis, the Northern long-eared bat, Lasionycteris noctivagans, the silver-haired bat and Myotis sodalis, the Indiana bat are among some of the thirteen bat species native to Illinois. All bats are in the order Chiroptera, and they are the only mammal that truly flies. The order name means “hand wing” which aptly describes the wing which is composed of a thin membrane stretched over the four fingers of a bat’s hands. The fingers can be spread when in flight or folded tightly together against their body when at rest. The thumb protrudes from the end of the forearm as a small claw providing assistance when walking or climbing. When flying, bats do not flap their wings as birds do, but move their wings in a circular “swimming” motion that provides not only lift, but great agility in the air.

*Myotis sodalis*, Indiana Bat, by USFWS Contributor Andrew King Public domain

Bats have small eyes and are thought to be able to see fairly well, but they use echo-location as a means of identifying insects or objects while in flight. This process involves the bat emitting a series of supersonic squeaks through its mouth, 30-60 per second, and hearing the returning echo when the sound bounces off an object. The complex ear can identify the direction, size, density and movement of the object. While in flight, a bat can catch a flying insect with its open mouth. Another method to eat-on-the-wing, especially when flying through clouds of insects, is to trap them in the folds of its wings. Bats have the ability to scoop these insects out of each wing while still in flight, sometimes somersaulting in mid-air while eating. A single bat consumes about 1000 insects an hour and will eat 6,000 – 8,000 mosquito-sized insects every night.

Bats spend most of their time “roosting”: resting or sleeping in a particular spot. Males and females tend to roost separately except during breeding season in late fall. Generally, they have two roost sites, one for daytime and another at night. Since most species tend to feed during late evening or nighttime hours, the night roost is near the feeding areas. This roost may be changed throughout the seasons as insect food groups tend to become more abundant at different sites.

*Myotis sodalis*, Indiana Bat, by Justin Bruno

Life spans vary by species, but generally bats in our area live about 30 years. Due to loss of habitat, widespread use of pesticides and herbicides, and direct persecution, bat species in Illinois have been declining for the past several years. However, on warm summer evenings, especially over quiet ponds or streams, pay close attention to the air above you and enjoy the small acrobatic flyers taking advantage of the abundance of available insects.