camouflage – 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.

Tracks In The Snow, pt.2

In the last blog we explored many of the characteristics of tracking. In this blog, we’ll explore tracks, eating patterns, and scat from animals that are active in northern Illinois throughout our winters. Many of these species live elsewhere, as well, and the information here can be applied to other species with the same characteristics as those in Illinois.

White-tailed deer, Odocoileus virginianus, domesticated horse, and bison, Bison bison, can all be found and observed in many urban and agricultural areas of northern Illinois. These hoofed mammals all walk on their toes, making a deep print of two toenails split down the center. The pointed end faces the direction the animal was traveling.

^{White-tailed deer, Odocoileus virginianus, by mirceax, Getty Images}

^{Deer tracks by florathexplora, Mar 2008}

^{Bison, Bison bison, grazing by belfasteileen, Getty Images}

Hoofed species in this area are all browsers and grazers. Browsers feed on leaves, fruit, and soft shoots of woody plants. One browser in this area, the white-tailed deer, leaves a distinct bite pattern exhibiting a ragged tear from the lower teeth and a clean cut from the upper teeth. Deer also use their lower teeth to scrape away soft bark from trees such as cherry, apple, willow, and sumac. Grazers feed on grass and lower-growing vegetation. These species include horses and bison which bite grass off close to the ground.

^{Rabbit tracks by Lorianne DiSabato, Jan 2025}

^{Squirrel tracks in snow by Tracy Rolling, Feb 2010}

Rabbits, squirrels, and chipmunks all move with a hopping motion. The smaller front feet land first and the larger hind feet land immediately in front of the front feet. Squirrels and chipmunks have five toes on the hind feet and four toes on their front feet. Rabbits have furred feet, effectively hiding the distinct toes, and their tracks appear as a large oblong hind foot in front of a much shorter front foot. The spacing of the tracks indicates of how fast the animal was moving.

Eastern cottontail rabbits, Sylvilagus floridanus, have teeth on both the upper and lower jaw, leaving a clean, forty-five degree angle cut a few inches off the ground. They prefer sumac, maple, apple and oak. Other signs that may be present where rabbits have eaten are scat piles. Their scat is small ovals that come out one at a time, so a pile of scat indicates that the rabbit stayed in that one spot for an extended period of time. Squirrels and chipmunks both have continuously growing incisors that leave distinct, small parallel grooves on the ends of woody shoots they have chewed.

^{Perching bird tracks in snow by Jim Forest, Feb 2017}

^{Webbed trails, Raritan River Bank by joiseyshowaa, Jan 2009}

Woodpecker tracks show two toes pointing in each direction. Perching birds have one toe pointing backwards and three toes pointing forwards. Larger birds of prey such as hawks and owls may have tracks that are blurred indicating feathers covering their toes. Waterfowl, including ducks and geese, will make flattened tracks showing webbing between their toes.

^{Owl wing prints and attack point by Chris Fournier, Dec 2013}

Many larger hawks and owls in our area hunt by soaring on wind drafts while scanning the ground below for prey. When a mouse or other small animal is found, the predator will dive from overhead to snatch up the prey or pin it to the ground before killing it, then possibly taking the prey to another location to eat. Wing marks and depressions in snowy areas are clear indications of an attack.

^{Raccoon tracks by August Ride, Jan 2018}

^{Opossum track by Phil Myers, Univ of Mich, Ann-Arbor, Feb 2009}

The North American raccoon, Procyon lotor, and Virginia opossum, Didelphis virginiana, have alternating prints. Raccoons leave a round print with five long toes that distinctly resembles a human footprint. Opossums also have five toes, but the outer one is opposable, like our thumb, and leaves a distinctive print with four toes pointing forward and one pointing to one side. You may also observe a wavy line between the opossum tracks as it drags its tail along.

Canines and felines have padded feet. Clues to the specie’s identity come from observations of the general shape of the imprint, how many toes there are, if there are claw marks at the ends of the toes, and the general pattern left by the trail of prints. Canines including dog, red fox, Vulpes vulpes, and coyote, Canis latrans, walk on their four front toes. Each footprint will show a back pad, a small pad behind each toe, and a claw mark in front of each toe. The overall imprint will be longer than it is wide. Red fox trails exhibit direct registration, with the hind foot stepping directly into the track left by the front foot but other canine species show indirect registration with front and hind tracks slightly separated.

^{Coyote tracks in snow by David Merwin, Mar 2007}

^{Bobcat track by Frank D Lospalluto, Feb 2016}

Felines include domesticated cats and bobcats, Lynx rufus. These animals have similar prints from walking on their four front toes, but a feline track shows the back pad and four toe pads in a circular impression, and no claw marks because they withdraw their claws when walking.

When observing tracks, keep in mind these points: whether hind feet and front feet are different, how many toes are showing, are there claw marks, is there webbing, feathers, or fur between toes, which foot is in front, and the shape of the print. Consider a tracking field guide or a visit to the Jurica-Suchy Nature Museum or a natural history museum near you for more information.

Tracks In The Snow

As a naturalist and observer, a person can spend a lot of time and effort trying to get close to wild animals, while most animals are trying hard to remain hidden from our view. With the arrival of winter, observing animals directly becomes even more difficult. Many stay hidden in nests and burrows, out of the wind and weather. Others stay out of sight during the day when predators are able to more easily spot prey against a snowy, white backdrop, and only come out during the night to find food.

^{Deer hiding from photographer in winter woodland, by Nicolo Bonazzi, 2016}

^{Eastern chipmunk makes an easy target for a sharp eyed predator, by Tom Murray, Feb 2021}

When an animal does move around, it will often leave tracks in the snow and mud, providing clues for us to study. Who made the track? Where did the animal come from or go to? Were they walking, searching for food, exploring shelter, or running, possibly from a predator? Observing individual prints or groups of prints taken as an overall pattern in the habitats where they were made can reveal interesting facts about each one.

Field guides are an excellent source of information to supplement observations, and you should get to know the following six terms. A track is an imprint of one foot whereas a trail is many tracks strung out in a pattern. Direct registration, made by a fox, occurs when only one imprint is visible because the animal places its hind feet directly into the track left by the fore feet. Indirect registration, made by a domesticated dog, is when the hind footprint appears just outside the fore footprint. An alternating pattern made by a raccoon shows the left hind footprint next to the right front footprint and vice versa. A hopping or bounding pattern from a rabbit shows front feet and hind feet together, with the hind feet appearing in front of the set of four prints.

^{Clockwise from upper left: Bird track by Sharon James, Jan 2013; A trail of tracks by Denise Kitagawa, Feb 2018; Direct registration: Red fox tracks, by Kent Kanouse, Dec 2013; Indirect registration: Dog tracks in snow, by Jeanne Fox, Dec 2007; Alternating pattern: Raccoon prints in the snow, by Andrew, Mar 2017; Hopping pattern: Rabbit tracks in snow, by Ann, May 2019}

There are four general types of tracks made from feet. Birds leave small, hopping, four-toed prints with either one toe pointing backwards and three toes pointing forwards, or in the case of woodpeckers, two toes pointing in each direction. Hoofed animals including deer, horses, and sheep have larger, two-toed prints. Animals with padded feet including dogs and cats leave a print showing four or five toes in front of a large back pad. A non-descript category includes all of the tracks for animals that do not have feet or are not using their feet when the track is made. Naturalists may also observe imprints in the snow or mud from other body parts. These may include feather markings from tails or wings, wavy lines from dragging tails, or packed down areas from dragging bellies.

^{Bird tracks in snow by zenjazzygeek, Mar 2016}

^{Hoofed animal track by florathexplora, May 2008}

^{Padded tracks from bobcat by Placeuvm, Jun 2007}

^{Wing swoop in snow, by Drew Brayshaw, May 2008}

In addition to tracks, other evidence provides information on what the particular animal was doing at that spot. Scat is often distinctive for each animal, and the contents can show what the animal has been eating. This will give us further clues to provide species identification, the size of the animal, and where it might be finding its food. Toothmarks or claw marks on nearby vegetation can help to indicate a specific species. Be sure to observe individual footprints, the overall trail of imprints, and the type of terrain and vegetation in the area. Also note how wet or dry the snow or mud is, as this may make prints easier or harder to distinguish details.

Tracking can be a rewarding activity, providing many clues to help identify animals active in your area and what they are doing during this time of the year. Next time, we will take a more in-depth look at some of the animals in the winter habitats of northern Illinois.

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

Great Horned Owls

The great-horned owl, Bubo virginianus, is native to much of the Americas, including most of North America and Central America and about half of South America. It is the second heaviest owl in North America, right behind the snowy owl, Bubo scandiacus, weighing up to five-and-a-half pounds with a wingspan between three and five feet.

^{Great-horned owl, Bubo virginianus, by Andy Reago&Chrissy McClareen, Aug 2012}

^{Range and distribution of Great-Horned Owl, Bubo virginianus by BirdLife International, 2014}

Feathers cover the entire body, including their feet, and are varying shades of browns and grays. Their backs and heads are mottled or barred in several patches. This coloration, especially when coupled with mostly nocturnal activities, provides excellent camouflage. Their ‘horns’ are actually feathers sticking upwards on either side of their heads. These are called plumicorns, but their function is not well understood. The feather structure of the wing allows owls to fly silently and includes a serrated leading edge to disrupt turbulence and softer feathers behind to help deaden sound.

^{Great horned owl plumicorns by Jean-pol Grandmont, Aug 2013}

^{Great horned owl wing structure by Peter K. Burian, Aug 2015}

The owl’s ears are covered by feathers, but are not symmetrical with one being higher on the side of the head than the other. This arrangement provides the owl with the ability to triangulate sounds and precisely locate prey in the dark or when prey is hidden, such as when an animal is moving about under a layer of snow. Their flattened face, shaped as a round disc, also helps to direct sound to their ears. Like all owls, their eyes are fixed in the sockets, but the bird can swivel its head almost 180° to either side allowing it to see in all directions.

^{Great horned owl talons by Curtis Bouvier, May 2010}

Great horned owls hunt from a perch, observing the area below them before diving swiftly and silently from far above. Their diet consists of small mammals, birds, amphibians, and a variety of snakes. Their talons are powerful and deadly, with a grip comparable to much larger birds such as golden eagles. Most prey is killed by being pierced or crushed in the talons. Owls may hunt and kill for more than their immediate needs and will cache their kills for future meals.

Great horned owls are not migratory. When an owl is ready to mate, courtship occurs in late fall and pairs mate for life, establishing a territory together in which they will live their entire lives. Most territorial defense is through hooting at a transgressor, but rare physical confrontations have been observed. If an owl cannot establish its own territory, it will live in silence among the fringes of other territories.

^{Great-horned owl juveniles, Bubo virginianus, by Alan Vernon, Jun 2010}

^{Great horned owl female & juvenile on nest by John Kees, Apr 2012}

Males are responsible for picking a nest site, almost always taking over a nest constructed by another species. Mated pairs breed once every two to three years, laying from one to six eggs. Egg laying occurs between late February and early April. The female alone incubates the eggs, never leaving the nest, while the male hunts and brings her food. After about 33 days, the eggs hatch. Young owls will start to fly after seven weeks, but take a full month or more to become proficient.

^{Great horned owl calling, Bubo virginianus, by Michael & Katie LaTour, Jan 2019 (at 0:02, 0:10)}

^{Great-horned owl pair calling by Bushman, Dec 2013 (at 0:18, 0:41, 0:51, 1:22)}

Owls are more often heard than seen. Although the females are larger than males, females have a smaller voice box and thus a higher pitched hooting call ending with a slight rising note. Juveniles can make hissing or screeching sounds and are often misidentified as barn owls, Tyto furcata.

You can learn more about these magnificent birds at the Jurica-Suchy Nature Museum. 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).

Illinois Owls

Owls are found year-round in northern Illinois, and they come in several sizes and shapes and live in various habitats. Owls found near urban areas are often active only in the evening or at night, making them elusive to find and observe their behaviors. Native owl species have a highly varied diet, hunting almost every animal smaller than themselves from insects and crustaceans to small mammals, reptiles, and amphibians. Some of their unique characteristics and places to find them are highlighted below.

^{Barn Owl, Tyto alba pratincola, by DonArnold, JSNM Museum and Great Horned Owl, Bubo virginianus, by DonArnold, JSNM Museum}

Great Horned Owls, Bubo virginianus, live in every habitat across North America, Central America, and parts of South America. Standing two feet tall with mottled brown and gray feathers, they are well camouflaged during nighttime activities. Their ‘horns’ are actually feather tufts sticking out above their ears, which may enhance hearing and make them easy to identify. Look for them at dawn and dusk in tall trees standing on the edges of open spaces. The Barn Owl, Tyto alba, hides in tree hollows or dense vegetation during the day, coming out to hunt at night. They are a foot tall with a distinct white face and chest and pale brown and gray backs. A high energy lifestyle requires them to eat more than other animals their size. They are mostly found in open fields near wooded areas that provide diverse habitat for prey.

^{Barred Owl, Strix varia by DonArnold, JSNM Museum; Northern Saw-whet Owl, Aegolius acadicus by DonArnold, JSNM Museum; Short-eared Owl, Asio flammeus by DonArnold, JSNM Museum}

Three owls are daytime hunters, but not often found in urban areas. Barred Owls, Strix varia, have small territories, covering no more than a few square miles during their lifetime. They are brownish gray with dark stripes on their bellies. They hunt during both daytime and nighttime and have been known to eat carrion if it’s easily available. Look for them in wetlands with mature woodland cover nearby. Another daytime hunter, the Short-eared Owl, Asio flammeus, is an abundant species standing about a foot tall and known by its brown speckles covering a cream colored undercoat, with a barred tail and wings and a light belly. Their diet is similar to other owl species, but they may also hunt rabbit and weasel. Look for them flying low to the ground in open areas including grasslands, meadows, and wetlands. The Northern Saw-whet Owl, Aegolius acadicus, is only six inches tall, with a round, light colored face and belly streaked with brown, and a brown back with light spots. They are highly maneuverable and can easily hunt in small spaces. These owls have incredibly sharp talons and beaks, and they are able to take down prey larger then themselves. They favor dense, mature forests, especially those containing conifers.

^{Eastern Screech Owl, Megascops aslo, by DonArnold, JSNM Museum; Long-eared Owl, Asio otus, by DonArnold, JSNM Museum}

The next two species are smaller, nighttime hunters, often found in urban areas. The Eastern Screech Owl, Megascops aslo, stands eight inches tall and is all grey or slightly reddish-tinged. This owl species has also been observed feeding on fruits and berries. They are found in forests, wetlands, and urban neighborhoods with mature trees. The Long-eared Owl, Asio otus, one of the most abundant owl species world-wide, is a foot tall, with black and brown plumage. They hunt by stealth, waiting on a perch for prey to come close, then pouncing. Look for them in urban settings with large trees and in many state park areas.

Snowy Owl, Bubo scandiacus, by DonArnold, JSNM Museum

A winter only resident, the Snowy Owl, Bubo scandiacus, stands two feet tall with distinctive, almost pure white plumage. They are active both night and day, and can cover large distances in their daily hunts. A large, ferocious hunter, they can take down prey larger than themselves. They are found in a widely diverse set of habitats including open grassland, wetlands, shorelines, and several of our area’s larger airports.

We have many owls on display at the Jurica-Suchy Nature Museum. Come in and learn from our newest Illinois In Winter display or our owl and other raptor displays. We are closed for the holiday break, but consider visiting us as we reopen for the Spring semester in early January. Check out our schedule and make a reservation to come see us at https://ben.edu/campus-links/jurica-suchy-nature-museum/.

Illinois Owls

Owls are a type of raptor, a bird of prey with forward-looking eyes, large talons, and hooked beaks. Raptors are known for having the best vision of any animal, and they are skilled hunters found across all habitats. Other raptors include hawks, eagles, falcons, kites, and vultures. There are nineteen owl species native to North America, and eight of them are regularly found in Illinois.

^{Pictures clockwise above: Black Kite by Martine LIU, Getty Images; Golden Eagle by Timu Abasov, Getty Images; Red-tailed Hawk by BrianEKushner, Getty Images; Turkey Vulture by James Opiyo, Getty Images; Peregrine Falcon by Harry Collins, Getty Images Pro}

Owls have large eyes that look forward and provide a wide angle of view. Their binocular vision helps these birds easily spot prey and accurately judge distances when either stationary or in flight. An owl’s eyes cannot move within the eye socket, so the owl must move its entire head, which is capable of rotating 270 degrees to see completely around itself. Their vision is extremely sensitive to light, and they are capable of hunting when conditions are quite dark.

^{Barn Owl face by QuentinJLang, Getty Images}

^{Great-horned Owl looking back by Celine Bisson, Getty Images}

The feathers on their round faces help to direct sound into their ears, which are located on either side of their head. Their ears are small openings covered by feathers that can enhance and separate sound waves, working like binocular vision, allowing the bird to identify how far and in which direction a sound originates. Their enhanced ability to detect movement around themselves, coupled with excellent vision, makes these birds of prey one of the top hunters in their environment.

^{Owl beak closeup by GrahamH, Pixabay; Snowy Owl talons by WWing, Getty Images; Black fur in owl pellet by Justin Smith, Getty Images}

Sharp beaks and talons are used to capture and hold prey, and to easily tear apart meat. All raptors have eight toes ending in a talon, or sharp claw, made of keratin. Owl talons are long and curved and are used to easily grasp a branch or a prey animal. Their beaks are made of bone covered with keratin, with very sharp edges. They have no teeth to chew food, and they eat their prey whole or in large chunks. Whatever is not digestible, including bones, fur, and feathers, is compressed into a wad in the owl’s mouth and spit back out as a pellet. An Investigation of owl pellet contents can reveal the prey the owl is currently eating.

Fringed ends of owl flight feathers by ElvisCZ, Pixabay

Owls have fringed outer edges to their flight feathers that deaden almost all sound made while flying, making it difficult for prey to detect an owl coming for them. An owl’s large, rounded wings and short tail provide great maneuverability while flying. Their excellent vision, hearing, and flight maneuverability allows them to hunt at night in areas with numerous obstacles including woodland and urban areas.

In the next blog, I will take a closer look at the owls in Illinois. At the Jurica-Suchy Nature Museum, we have several displays that highlight the various characteristics of owls and other raptors. We are closing for the holiday break, but consider visiting us as we reopen for the Spring semester in early January. Check out our schedule and make a reservation to come see us at https://ben.edu/campus-links/jurica-suchy-nature-museum/.

Butterflies

I recently visited The Butterfly Place in Westford, Massachusetts. It was quite nice to walk through and learn about the various species and habits of these beautiful and lively insects.

Clockwise from upper left, all pictures by Don Arnold: Brown Clipper butterfly, Parthenos sylvia; Giant swallowtail butterfly, Papilio thoas; Julia butterfly, Dryas julia; Monarch butterfly, Danaus plexippus; Malachite butterfly, Siproeta stelenes

Butterflies come in a variety of colors and patterns providing camouflage to hide from potential predators, identifying an individual to potential mates, and/or allowing an insect to absorb heat needed for daily activities. The colors we see can come from colored pigments that reflect light of a specific color or from structural pigments that take on different colors depending on the angle and intensity of reflected light. Structural pigments produce blues, whites, and colors with a metallic sheen. Genes control which pigments appear in each part of their wings to create the multitude of patterns. Variations in just a few genes may determine that a pattern in one species is slightly different in size, shape, or color in another species, or completely different in a third species.

Blue morpho, Morpho peleides, with brown & white pattern vs same colors and slightly different pattern on Owl butterfly, Caligo eurilochus

Butterflies eat by sipping sweet nectar from a variety of flowers. Their tongue, called a proboscis, forms a hollow straw that restricts them to a liquid diet. When not eating, you can observe the proboscis curled up in front of their mouth. When uncurled, it forms a long tube, able to reach deep into a flower to the base where nectar is stored. Watch the video below as this monarch inserts its proboscis into the base of the lantana as it feeds. Many butterflies enjoy juice from fruit, especially as it starts to decompose to a softer, more liquid-like stage.

Rice paper butterfly, Idea leuconoe, probing for nectar

Puddling is another feeding activity where butterflies take in liquid from puddles, wet gravel, sweat, and scat. These are all sources for minerals and salts needed for egg development. Females may find their own puddling sources, but males also engage in this activity, passing along a complex package of sperm, minerals, salt, and other nutrients to females during mating.

Clockwise from upper left, all pictures by Don Arnold: Piano key butterfly, Heliconius melpomene; Rice paper butterfly, Idea leuconoe; Sara butterfly, Heliconius sara; Scarlet swallowtail butterfly, Papilio rumanzovia; Zebra longwing butterfly, Heliconius Charitonia

Butterfly houses are interesting and fun places to observe many of these species and their behaviors up close. We can provide for our native butterflies by learning which plants host caterpillars and which plants provide nectar for adults. Select these plants for your garden, or place potted plants on an outside porch during warmer months. You can provide additional habitat for butterflies and other small insects by mowing less frequently, limiting the use of pesticides in your yard, and leaving small brush piles in your garden.

Bird Eggs

It is spring in the northern hemisphere, and many birds are claiming territories, finding mates, and establishing nesting sites. Raising new families will take most of the summer and early autumn. As we watch birds who have laid their eggs, it may seem that not much happens until the young hatch, but there is lots of activity taking place.

^{RWBB calling by mirceax from Getty Images}

An ovum, the female reproductive cell, starts its journey to become an egg in the oviduct where it is fertilized by stored sperm from a male and encased in a glob of protein-filled gelatin to form a yolk. Additional proteins, known as the albumin or egg white, are added to nourish the embryo as it grows inside the egg. Calcium carbonate, a mineral added by special cells in the bird’s uterus, encloses the gelatin-like mass of protein and embryo, slowly hardening into the egg’s shell. Egg shells are not completely solid, but are perforated with many minute holes that allow air to reach the developing embryo. Pigmentation is squirted onto the shell adding color and pattern to the outside. A coating of protein determines the outer texture of the egg which may be smooth, glossy, dull, rough, or powdery.

^{Egg collection, Jurica-Suchy Nature Museum, Benedictine University, Lisle by DonArnold}

The total number of eggs laid at one time is called a clutch and some bird species lay only one a year, but many species produce two, or more, annually. A consistent number of eggs is found in each clutch, although additional clutches in the same year may contain fewer eggs. Eggs vary widely in size, shape, and color among various bird species. Egg shapes may be determined by the location of the nest. Cavity nesters tend to have rounded eggs, while cliff dweller’s eggs are often oval with a broad end on one side and a pointed end on the other to prevent the egg from rolling very far. Where a clutch has a greater number of eggs, pointed shapes fit into smaller spaces enabling the mother to easily cover them all when sitting on the nest.

^{Nesting female hummingbird by jaypiercestorffphoto}

Incubation is the process of keeping the eggs warm. An adult usually develops a brood patch underneath its belly where feathers and down disappear and blood vessels close to the skin’s surface can warm the area that is in direct contact with the eggs. Incubation periods are consistent in each species, but may be lengthened by abnormal cold spells.

^{Blue robin eggs in nest by Dennis Flarsen, Pixabay}

^{Western bluebird eggs by Summit to Seashore Birding, Sep 2007}

Color is added into the shell material before it hardens. Colors may vary in hue and saturation on individual eggs, and the deepest hues are often found at the largest end. Pigments are chemicals with complex molecular structures that produce color when mixed with water. Birds have two pigments: reddish-brown hues and bluish-green hues. Here are several theories as to why eggs have markings, but exact reasons are not known.

Heavier pigments are often found in birds that lay their eggs in open, exposed environments, and the markings may serve as camouflage. Many cavity nesters lay white eggs, which are well hidden from other birds, predators, and the sun. Some eggs laid in exposed nests may still be brightly colored, but covered by the female most of the time.

^{Quail eggs showing pigmentation by Piyachok from Getty Images}

Darker colors and markings are often found among species that breed in cooler climates. Pigments are known to absorb UV radiation from the sun and not allow it to harm a developing embryo. But, light absorption by an area of pigmentation generates more heat inside the shell, which may also be harmful. Pesticides and other chemicals in the environment can cause thinning of the shell casing, making them more susceptible to breakage. Pigments tend to gather at weaker spots in the shell casing and have been shown to strengthen the shell.

Several aspects of bird egg development are not yet understood, and many theories are under investigation. An interesting question currently under review is whether a bird, or another animal such as a predator, sees different aspects of the light spectrum than humans. If so, what do birds see when they look at an egg? A new bird’s life starts in an egg, a small and wonder-filled package that has been much studied and yet still presents many unanswered questions.

To learn more, consider visiting your local nature museum.

The Jurica-Suchy Nature Museum at Benedictine University in Lisle, Illinois, has an extensive egg collection displayed by clutch size and covering almost 200 bird species.

Snake Defense

Snakes, with over 3,000 species worldwide, are one of the largest groups of reptiles. They are found on every continent except Antarctica and live in every type of habitat including freshwater and saltwater. They have numerous enemies and have developed defensive strategies enabling them to survive and prosper.

^{Catching a snake on the wing by CuriousLog, Jun 2007}

^{Red-shouldered hawk with snake by Don Loarie, Mar 2018}

^{Great Blue Heron eating snake by C Watts, Jan 202}2

Snakes must deal with threats from a wide range of animals. Bird species that prey on snakes include raptors, ravens, egrets , and storks. Nocturnal hunters, including owls, have excellent sight in low-light conditions and often hunt by spotting movement among foliage. Likewise, during daytime hours, red-tailed hawks and eagles can spot movement on the ground while soaring. Snakes are normally line-of-sight hunters, and are often unaware of threats from above, giving avian predators a distinct advantage.

_{^{American crocodile, Crocodylus acutus by Florida Fish and Wildlife, Feb 2021; Wolverine by Maia C, Aug 2012; Skunk by D Fletcher, May 2016}}

Most mammal predators are larger, more agile, and faster. Badger, wolverine, and racoon are all excellent climbers and may hunt from an elevated perch. Wolverine and skunk are also burrowers that will dig out their prey from underground. Snakes living in saltwater and freshwater environments are eaten by predators such as crocodiles and snapping turtles. In addition, some larger snake species regularly hunt smaller snakes.

^{Copperhead on dead leaves by Abbott Handerson Thayer, Mar 2022}

Snakes use a number of non-aggressive strategies to avoid confrontation and escape. Their best defense is to remain hidden, using colors and patterns to break up the outline of their body, allowing the snake to blend with the background foliage and be overlooked by any predators. Another passive strategy is balling, involving compressing their body into a tight coil or ball, typically with the head tucked in to protect this most vulnerable area. Playing dead is often an effective means to escape predation, honed to perfection by the Western hognose snake. This snake convulses its body, rolls onto its back, and lets its tongue loll out of its mouth. It may vomit or spew blood, release fecal matter or musk, all in its attempt to convince a potential predator that it is already dead and no longer appetizing.

^{Timber rattlesnake balled and hidden by Peter Paplanus, Apr 2022}

Mimicry is a development that has taken place in some species over long periods of time. Batesian mimicry is when a harmless species has evolved the coloration of a more dangerous species to fool a predator into leaving it alone. Scarlet kingsnakes of the southeastern United States are quite harmless but look very much like Eastern coral snakes, a venomous species in that same area. Auditory mimicry involves creating sounds used by more dangerous snakes. Fox snakes, found in deciduous forests, often vibrate their tails in leaf litter, making a buzzing noise very similar to the sounds made by rattlesnakes living in the same area.

^{Scarlet kingsnake by FWC Fish & Wildlife Research Institute, May 2015}

^{Eastern coral snake by FWC Fish & Wildlife Research Institute, Sep 2014}

Snakes often use one or more methods of intimidation. Bright display colors are found among many venomous species and serve as a warning to potential predators that this snake is dangerous. Another form of intimidation involves a snake inflating its body or a body part to make it look bigger. The puff adder inflates its whole body by filling its lung with air. Cobras hold their heads high and flare out an extra fold of skin on either side of their heads, commonly called “hooding.” Intimidation may also involve auditory cues including the rattling of a snake’s tail and the hiss emitted by cobras as they bring up their heads.

When the above strategies do not allow the snake to escape, most species will not hesitate to strike. Several species do not bite, striking with the nose or an open mouth; however, all venomous snakes will bite in self-defense, although they may not inject venom. A few species are able to spit venom, used purely as an act of self-defense, although if the venom targets an eye or nasal passage, the results can be extremely painful.

Snakes are some of the most interesting species with a lifestyle very different from our own. They have many strategies for keeping themselves safe from wild predators, and will be around for us to observe, learn about, and be fascinated by.