extreme weather – Discover-Nature

The High Life, animal species

In the last blog, we investigated the conditions and constraints of living at high altitudes, generally above 10,000 feet. A few physiological adaptations listed included enhanced breathing and blood supply to get more oxygen to the body, internal temperature regulation allowing some mammals to adjust to a colder environment, and smaller plants requiring less moisture and having a short growing season.

^{Common springtail, Orchesella cincta, by Mvuijlst, Feb 2009}

^{Springtail, Isotoma caerulea, by Andy Murray, Jul 2014}

The Himalayan jumping spider, Euophrys omnisuperstes, is generally found above 22,000 feet, living among rock crevices and feeding on stray insects blown upward by rising mountain winds. The spider also feeds on springtails, Collembola, once considered an insect but now classified as a free-ranging hexapod. These tiny organisms have antifreeze compounds in their blood, enabling them to live in higher, colder habitats.

Reptiles from four lizard species have been found living in higher elevations. Two species of iguana in the genus Liolaemus live in Bolivia; a third iguana species, Liolaemus tacnae, lives in Peru; and an Asian lizard, Phrynocephalus erythrurus, lives on the Tibetan plateau. All were found between 16,000 feet and 18,000 feet, but very little is known about them since these areas are difficult to access for study.

^{Golden eagle, Aquila chrysaetos, by Giles Laurent, Dec 2021; Andean condor, Vultur gryphus, by Bastihitzi, May 2013; Alpine chough, Pyrrhocorax graculus, by Jim Higham, 2008}

Birds can be found living near mountain tops year-round. The Alpine chough, Pyrrhocorax graculus, lives in social flocks from the Alps to the Himalayas. Standing 15″ high with a 30″ wingspan, they have black feathers with distinct yellow beaks and red legs. They eat insects and berries in summer, but have become well-adapted to scavenging in winter, especially around ski resorts. The Andean condor, Vultur gryphus, another social bird, roosts on cliffs and outcrops above 16,000 feet. The steep terrain provides additional protection from potential predators. Golden eagles, Aquila chrysaetos, are found world-wide in many habitats. In the mountains, they hunt marmot, hare, and young goats at lower elevations, but nest in eyries, large cliff-hugging nests at higher elevations. With wingspans up to seven feet, they can dive at speeds of up to 150mph over unsuspecting prey.

^{Left top to bottom: Common crane, Grus grus, by Savithri Singh, Feb 2020; Whooper swan,Cygnus cygnus, by KyoichiNarukami, Japan, Jan 2012; Bar-headed goose, Anser indicus, by J.M.Garg, India, Mar 2000; Ruppell’s Griffon Vulture, Gyps rueppellii, by Lip Kee, Kenya, Aug 2008}

High altitude bird species with physiological adaptations for breathing and blood supply include those whose migration routes take them over the world’s highest mountain ranges. Ruppell’s Griffon Vulture, Gyps rueppellii, with an 8-foot wingspan, has been observed at altitudes exceeding 36,000 feet over the Ethiopian Highlands of Central Africa. The common crane, Grus grus, lives across eastern Europe and northern Asia, migrating over the Alps to Africa, India and southern China. The bar-headed goose, Anser indicus, and the whooper swan, Cygnus cygnus, both live in south Asia and migrate over the Alps to central and sub-Arctic Asia to breed.

^{Above: Large-eared pika, Ochotona macrotis,}
^{by Karunakar Rayker, Ladakh India, Feb 2008}

^{Right: Snow leopard, Panthera uncia, by Vassil, Aug 2007}

The heights of the Himalayas support mammals that can concentrate their hemoglobin and allow the blood to carry more oxygen, avoiding issues with hypoxia, a shortage of usable oxygen in the body. Species with this physiological adaptation include large-eared pika, Ochotona macrotis, living above 7,700 feet up to 20,000 feet; wild yak, Bos mutus, which have larger heart and lungs than domesticated yaks; and the snow leopard, Panthera uncia, living above 3,000 feet up to 18,000 feet. The snow leopard has short, heavily furred limbs and a long, heavy tail for use as a blanket. Its large nasal cavity and strong chest allows more oxygen to be taken in with each breath.

^{Ethiopian wolf, Canis simensis, by Charles J. Sharp, Ethiopia, Dec 2017; Mountain goat, Oreamnos americanus, by Darklich14, Colorado, Aug 2009; Tibetan argali, Ovis ammon, by DonArnold, Jurica-Suchy Nature Museum, Mar 2026; Guanaco, Lama guanicoe, by Charles J. Sharp, Chile, Oct 2025; Yellow-rumped leaf-eared mouse, Phyllotis xanthopygus, drawing by Charles Darwin, 1832}

Mountain goats, Oreamnos americanus, can climb steep cliff faces with hooves that grip ledges and rock surfaces in the Rocky Mountains. The yellow-rumped leaf-eared mouse, Phyllotis xanthopygus, feeds on grains, seeds, roots, and insects in the Andean Mountains of Chile, living at altitudes to 22,000 feet. Guanaco, Lama guanicoe, a member of the camel family, lives in the Andes up to 13,000 feet and has about four times as many red blood cells as a human does. The Ethiopian wolf, Canis simensis, is an endangered species living up to 15,000 feet in central Africa with populations fragmented by pressure from human farming activities. Tibetan argali, Ovis ammon, is a wild sheep found in the Altai Mountains of Mongolia up to 19,000 feet. The ewes and lambs prefer steep, treacherous slopes as protection against predators.

Scientists continue to study species in these habitats to learn more about their specific adaptations and survival abilities in a harsh environment. You can learn more by visiting zoos or nature museums near you to investigate these fascinating species.

Spring Migration

Meteorological spring starts Sunday, and we are already starting to hear the calls of early migratory birds, heading north from southern wintering grounds, working to establish territory their among the best nesting sites available.

Red-winged blackbird, Agelaius phoeniceus, singing by Rhododendrites, May 2023

Some birds, including red-winged blackbirds, Agelaius phoeniceus, get their cue to start spring migration as temperatures get warmer. These species head to prairies, forests, and wetlands to claim a location they can protect, call for a mate, and establish a nesting site with good protection and food sources. Other birds, including many warbler species, return in spring when daylight hours lengthen. Generally flying at night, they use star positions and the Earth’s magnet field to guide them. If nights are stormy or heavily overcast, early morning may find hundreds of them waiting in fields for clear skies. Birds may also stop for a day or two in areas located on the southern shores of any large body of water to rest and feed before crossing.

Red-winged blackbird, *Agelaius phoeniceus,* flock at sunset by Jerry Segraves

Bird species around the world generally follow established flyways, established routes over specific locations between their southern and northern territories. Many migration routes do not follow a straight path. Some species have historical stopover or feeding locations that provide a rest point along the way. Other species may not be able to cross a mountain range; or a large body of water can act as a barrier for land birds, but may be a required food source for wetland birds.

Arctic tern, *Sterna paradisaea*, adult & juvenile by Charles J Sharp, Aug 2025

Arctic tern, *Sterna paradisaea*, in flight by Charles J Sharp, Aug 2025

Long distance migration routes are most common for birds wintering in subtropical and tropical areas and breeding in the northern hemisphere. Long migrations in the southern hemisphere are far less common because there is less land near the South Pole to support breeding activities. The record holder for migration distance is the Arctic tern, Sterna paradisaea, overwintering in Antarctica and breeding in Arctic locations, a round trip between 30,000 and 55,000 miles. Some shorter migrations are between upper and lower altitudes in mountainous regions.

Penguin migration map by Fred Cooke
& Jenni Bruce, Aug 2011

Dusky grouse male, *Dendragapus obscurus*, displaying by US NPS

Most birds migrate in flocks, which reduces the energy needed to fly long distances and provides added protection against predators. Penguins migrate without flying. Most penguin species swim between locations, covering up to 1,000 miles round trip. A few species cover long distances on foot, including dusky grouse, Dendragapus obscurus, in the Rocky Mountains which walk from lower to higher elevations. However, a flock may encounter unfavorable weather or flying conditions that causes a large number of birds to stall in one location, introducing other risks including depleted food sources and predation by land-based animals.

At the Jurica-Suchy Nature Museum, we host a nature walk every other week to observe changes in our campus including the birds that are moving through the area. There are many birding groups worldwide that provide opportunities to observe and learn about migratory birds in every location. Consider joining a group, or take your own bird walk as we have clear days and warming temperatures and see who’s on the move in your area.

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.

Seaside

Shorelines of oceans, seas, and large bodies of water around the world are habitats for plants and animals that thrive in challenging conditions. Tides occur twice each day when water levels rise over a six hour period to cover large areas before receding to leave those same areas open to the air until the next tide starts to move inland again.

^{Nearshore habitat zones by King County, WA;} ^{Littoral Zones by US Government}

Shoreline habitat has been classified into zones often known by many different names. The intertidal zone is the area affected by changing temperature and salinity conditions as water moves in and out with each tide. The subtidal zone is the lowest and is exposed to air only during extreme spring tides or storms. The backshore zone is the highest and is exposed to water only during extreme spring tides or storms.

^{Starfish & anemone in tidal pool by Jonathan Levy}

^{Sea urchin in tidal pool, Bahia de Banderas by Jim Hoffman, Mar 2017}

Many species of animals live in each zone and are adapted to living completely submerged as well as completely uncovered by water for several hours each day. They handle the change in temperature and salinity with exposure to air or water. Tidal pools may keep some animals submerged for far longer periods. Temperature, dissolved oxygen, and salinity change far less for these organisms.

Bryozoans by John Turnbull, Sep 2021; Sea anemone by Barb Ignatius; Squat lobster, Glathea rostrata, by FWC Fish & Wildlife Research Institute, Aug 2013

Some species can be found in every zone in the ecosystem, but many are anchored to rocks or dug into the bottom. Species may prefer one zone, but get washed into another zone by wave action. Many organisms have tough outer surfaces to put up with battering waves and exposure to sun and wind. All of the occupants are subject to a wide range of predators from those that move on dry land to underwater hunters. Let’s take a look at a few of the creatures able to live in these ever-changing conditions.

The sea anemone clings to rocks and protects itself by drawing in its tentacles to become a jelly-like blob. The squat lobster can be found under stones along the shoreline. Its tail is fan-shaped and facilitates quick escapes when the animal is threatened by pulling the lobster through the water with powerful strokes. Bryozoans are small filter feeding organisms protected by a hard exoskeleton that the animal can withdraw into for protection.

^{Dog whelk, Nassarius livescens, by Budak, Dec 2016}

A mollusk called a dog whelk is a stealth predator often found on rocky surfaces. It uses its tongue to drill through the shells of other mollusks, where it squirts a digestive juice into the prey’s shell which kills and partially digests the prey. The dog whelk then uses its tongue to suck up the soupy meal. The starfish is another fierce predator. It wraps its arms around a shellfish and pulls it apart. Upon opening the shell, the starfish pushes its stomach out of itself and into the prey’s open shell where it empties its digestive juices inside, and similar to the dog whelk, creates a tasty, soupy, meal.

Sea urchins can be found clinging to hard surfaces where they feed on algae and other small, encrusted animals. Fan worms look like a leathery tube among underwater rocky crags. Several feathery tentacles fan out into the water to filter out microorganisms flowing by.

Shorelines create a habitat that is constantly changing with tides moving in and out, inconsistent weather conditions, and a large variety of flora and fauna coming and going. Learn more about this fascinating habitat at the Jurica-Suchy Nature Museum or a natural history museum near you.

^{Botanical beach at Port Renfrew by James Wheeler; Feather Boa kelp in the surf by Kqedquest, May 2007; Rocky intertidal zone in Oregon by Minustide, May 2015}

Heat Effects

The midwestern United States is experiencing a heat dome this week. This is the result of a high pressure system hundreds of miles across and moving very slowly. Air in the upper atmosphere of a heat dome is already warm, but is still cooler than the air below, and cooler sir sinks towards the Earth’s surface. As the air moves downward, it compresses air molecules together releasing heat, making the lower layers even hotter and drying out the area as moisture evaporates. With little or no moisture, no clouds form to relieve the heat and dry conditions.

^{Heat Dome over Eastern US by National Weather Service, Jun 26 2025}

Humans have a variety of ways to cope with high heat including being less active, drinking plenty of fluids, and remaining in shady or air-conditioned areas. Wildlife still has to get food and water every day and may have fewer opportunities available to them to avoid the high heat. Let’s look at how the heat is affecting a few of the backyard species common in the Midwest.

^{Photinus pyralis, Big Dipper firefly by Terry Priest}

Fireflies are cold-blooded, or ectothermic, and prefer warm and humid areas. They come out in the early evening and as their bodies warm, they become more active, flying and flashing more frequently, communicating with other fireflies to find a mate. Eggs are laid soon after mating, but these will perish if they do not remain hydrated. Turning off outdoor lighting for a few hours in the evening and maintaining taller, well-watered vegetation will help fireflies during hot and dry conditions.

^{American Toad by Brad Carlson, Mar 2012; and Bullfrog at Waterfall Place by DonArnold, 2022}

Frogs and toads are also ectothermic and require heat from the environment to live. Species worldwide, including American toads and bullfrogs in our area, find temperatures in the 70s to be ideal. As temperatures move into the mid-80s, these species and others are prone to dehydration and heat stress. In addition, they normally look for shady and humid areas to regulate their body temperatures, but the lack of moisture in a heat dome does not make those niches easy to locate. Maintaining shady, well-watered areas of the garden provides refuge for many amphibian species.

^{Cardinal looking to stay in the shade by Don Arnold, 2023}

Birds are often affected by extreme heat. Most birds have lower body temperatures than the outside air. This allows birds to easily dissipate heat from high energy activities, such as flight. Once the outside air gets above a hundred degrees, birds cannot lose heat to the atmosphere and become severely compromised by heat and dehydration. Rapid open-mouthed breathing, changing eating times to early or late in the day, sitting with wings outstretched, or exhibiting poor balance are all signs of heat stress in birds. Providing shady, undisturbed areas and readily available water sources gives birds the opportunity to move around less and stay hydrated.

Wild animals have to deal with weather extremes just as we do. Come to the Jurica-Suchy Nature Museum or a nature center near you to learn more about providing opportunities for wildlife to survive heat, drought, and other environmental conditions.

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

Pamir Wildlife

The Pamir Mountains form the western edge of the Tibetan Plateau. A pamir is a high-altitude valley or plateau surrounded by mountains. Many valleys in this range exceed 14,000 feet in altitude, and peaks reach well above 20,000 feet, making these some of the highest mountains on the Euroasian continent. The area contains the major center of glaciation in this part of the world, and all of the nearby mountain ranges are still being forced upwards by movement of the Indian-Australian tectonic plate pushing northward under the continent.

^{Pamir Knot, Hindu Kush satellite image by Jeff Schmaltz, NASA}

^{Pamir Mountains by Amanov Dmitry, Jun 2014}

Wildlife in the Pamir region is well-adapted for high altitudes, long, cold winters, and short growing seasons. Mountain people use the land for grazing large herds of domesticated sheep and yaks, but grazing space must also be shared with wild sheep, wild yaks, dozens of bird species, over 700,000 insect species, and many large predators. Let’s look at a few of the more notable species.

^{Himalayan vulture, Gyps himalayensis, on Rupin Pass trail by SahanaM, Oct 2018}

^{Himalayan vulture, Gyps himalayensis, by OK-Photography, Getty Images}

The Himalayan vulture, Gyps himalayensis, inhabits the pamirs up to 18,000 feet. These birds easily soar on warm thermal updrafts, but are not capable of long distance flight. They are often found basking in the sun on high, rocky perches. Traveling in large flocks, they follow grazing herds, keeping watch for dead animals. They can be aggressive to most other predators at a kill site, but give way to snow leopards, wolves, and cinereous vultures. The biggest threat to current populations is from drug overdoses of diclofenac, an anti-inflammatory drug that has been heavily used to treat injury in domesticated herds.

^{Herd of Marco Polo sheep in the Tien Shan mountains, by okyela, Getty Images}

^{Marco Polo sheep, taken at Berlin Zoo by Cloudtail, Aug 2018}

The Marco Polo sheep, Ovis ammon polii, is the largest sheep in the world, with large, spiral horns reaching six feet in length, with spans up to five feet across. They feed in the early morning and spend the remainder of the day basking quietly in sunny grassland. Their feet and hooves provide sure footing among sharp ridges and loose scree, and they spend nights sleeping among large boulders for protection. As the climate has warmed, there has been a loss of snowpack, resulting in less available fresh water for drinking and growing thick grasslands. These factors are driving the sheep to lower altitudes where they are more susceptible to predators including gray wolves, red fox, and brown bear.

^{Snow leopard, Panthera uncia, by Irbis1983}

^{Snow leopard, Panthera uncia, by Bernard Landgraf, Jan 2005}

Snow leopards, Panthera uncia, have seen a steady decline with a current population of fewer than 10,000. Their thick fur, gray/white with black rosettes, provides great warmth in colder altitudes, but is prized by poachers, who constitute their main threat. They are solitary animals, active for several brief periods daily, and dependent on healthy populations of ibex and sheep to eat. Powerful legs and furred paws enable them to pursue prey, in any weather, across rocky mountain terrain. After making a kill, they move the carcass to a protected area to eat. At one time, these predators were hardly ever seen, but overgrazing has caused humans to move domesticated animals into areas where snow leopards normally hunt, providing more opportunities for these predators to be killed by protective herdsmen.

^{Wild yak, Bos mutus, by Adarsh Thakuri, Jun 2008}

^{Wild yak, Bos mutus, by the Editors of Encyclopedia Britannica}

Wild yak, Bos mutus, can live in extreme conditions at altitudes up to 20,000 feet. They are large animals standing 6′ tall, weighing 1500 pounds, with black horns spanning six feet. Black, long, fine hair hangs all the way down to their feet, providing warmth for the body and legs. Yaks are very social, forming large herds of several hundred animals. They graze in two groups, with the females typically found about 300′ higher in altitude than the males. Females with young often keep to high, steep slopes where predators, including wolves and bears, are less prone to roam. Wild yaks readily hybridized with domesticated species, resulting in a natural spread of the gene pool.

^{Apollo swallowtail butterfly, Parnassius apollo, by Hectonichus, 2007}

^{Clouded Apollo swallowtail butterfly, Parnassius apollo, by Zeynel Cebeci, Adana Turkey, May 2016}

Butterflies are another common inhabitant of high-altitude mountain regions, particularly from the genus Parnassius, known as the snow Apollo swallowtail family. They are color adapted with dark bodies and wing bases that readily absorb heat from the sun providing a source of quick energy. Their normal ranges are found above 14,000 feet, and they are active for only 2-3 months annually, during the short summer season. Dozens of species have been identified with many having very small populations, numbering only a few hundred individuals. Poaching for collectors remains their main threat.

At the Jurica-Suchy Nature Museum, we have many of these and other species on display in our mountain region diorama. Consider a visit to learn more about the wildlife of high-mountain plateaus worldwide.

^{High-altitude species from around the world on display at the Jurica-Suchy Nature Museum include: Marco Polo argali sheep, Alaskan brown bear, bighorn sheep varieties, mountain goat.}

Insects Over Winter

It is starting to get chilly in the Midwest as we head toward winter. Insects also recognize the shorter daylight hours and dropping temperatures. They use two main strategies to cope with winters: freeze avoidance and freeze tolerance. Avoidance may require travel or a dry place to stay warm. Tolerant insects can stay here and control their body’s response to freezing temperatures. Staying in place has several advantages including being able to emerge early in spring, allowing those insects to feed before predators are out.

^{Clockwise from upper left: Monarch butterflies on migration by Dopeyden, Getty Images; Cecropia moth cocoon by Sylvie Bouchard, Getty Images; Milkweed bugs by Rick Wood, Rick Wood’s Images; Four-lined plant bug, Poecilocapsus lineatus, by Heather Broccard-Bell, Getty Images Signature; Common pill-bug by Ines Carrara, Getty Images}

Those insect groups that opt for traveling to warmer climates often make a one-way trip. Monarchs are one of the best known insect migrators. Monarchs east of the Rocky Mountains leave in early fall to arrive at overwintering sites in the mountains of Mexico. Their offspring return to the southern U.S. in spring to breed, and this second generation returns to the East and Midwest over the following summer. Monarchs west of the Rockies overwinter in Baja, California, and many of the same individuals that fly south do return, but their trip is considerably shorter allowing time for breeding during summer months in the northwest U.S.

^{Honeybees in hive by OK-Photography, Getty Images}

Many different species of insects can control or stop ice formation in their bodies. Honeybees cluster together and shiver, generating enough body heat to keep the air above freezing in their hive. Other insects get rid of all the food and water in their bodies, becoming dehydrated and unable to freeze. Some species can control where ice crystals may form in their bodies, and prevent their formation inside cells that would cause harm to the insect. Insect species that retain some water use cryoprotectants, chemicals resulting from large amounts of sugar. One such chemical is glycerol, which lowers the freezing temperature of water and other liquids.

^{Dragonfly larva with fish by Mauribo, Getty Images Signature}

^{Fast running stream by Mburnham, Getty Images}

Some insects remain active throughout the winter. Aquatic insects in immature stages can easily spend the winter in fast moving or deeper water that does not freeze. Some insects move inside warm and protected places like attics, sheds, and gaps in house walls. They also overwinter in tree cavities, under bark, inside dead plants, and in old burrows. Allowing vegetation with hollow stems to stand through the winter will provide many populations a safe place to spend the season.

The insect version of hibernation is called diapause, when growth and development is halted until longer daylight hours prevail. Late winter weather patterns with warm periods interspersed with cold periods endanger many species. Another change we have experienced in recent years involves warm temperatures lasting later in fall and starting earlier in spring. These changes interrupt the historical natural cycles, causing insects and other animals to abort hibernation and actively look for food or mates. Food plants do not produce enough to support animal populations, or another cold period returns, and species are not able to adapt, and often perish.

^{A garden in winter by Vermontalm, Getty Images; Snag and deadwood in winter by BayDavn0211, Getty Images; Spring garden and returning insects by Anthony Lerma, Getty Images}

Insects are a vital part of healthy habitats, providing pollination services and food to many species. We can help overwintering insects by leaving dead stalks standing until late spring to provide safe habitat. Leaves left piled up provide nutrients, insulation, and a place of shelter. Uncovered soil can also host ground nesters such as native bees. Snags and logs provide lots of cavities protected from the weather. Selecting some plant species that bloom early or late in the year will provide additional food at those times. Growing plants in clusters enables insects to find all they need in one place. With a little planning, everyone’s backyard can be an inviting habitat for insects year-round.

Tornado

Springtime in the Midwestern United States brings with it everything from light to heavy showers, including tornados. In Illinois, we see an average of 54 tornados a year, with most of them occurring in the month of May. Tornados also occur in other parts of the world during springtime, including Europe, eastern and western China, South Africa, southern Brazil and both the east and west coasts of Australia, but not as frequently as in the U.S.

A majority of storm fronts move from southwest to northeast, which is a contributing factor in the Midwest to the formation of violent storms. There are three types of tornados. Non super-cell tornados are small, narrow, and last for only short periods of time, usually only a few minutes. Wind speeds are low, topping out near 80 mph, capable of causing only minor damage. Squall line tornados are generated by smaller thunderstorms traveling one after another forming periods of rain interspersed with calmer conditions. As the end of a squall line bends, small tornados may form with lower wind speeds, usually causing no damage. Super cell thunderstorms are the largest, most powerful storms that can generate tornados ranging from small to great in size and intensity.

^{Upper left: Thunderstorm during VORTEX2 by Sean Waugh, NOAA-NSSL Lower left: Funnel cloud approaching the ground by National Severe Storms Laboratory, NOAA Right: Supercell often associated with violent weather by National Severe Storms Laboratory, NOAA}

Rainstorms form when cool, dry air overlays a layer of warm, moist air. As the warm air rises to higher altitudes, where there is less air pressure, it expands and cools, losing its ability to hold moisture. As water condenses from the cooling air mass, water vapor floating on the air forms clouds. As more warm, moisture laden air moves into the system, the water vapor droplets become heavy enough to fall as rain. As rain falls, it cools the lower air layer, reducing the warm air flow until the rain stops.

^{Photomontage of the evolution of a tornado : Composite of eight images shot in two sequences as a tornado formed north of Minneola, Kansas on May 24, 2016, by Jason Weingart}

Thunderstorms form in the Midwest from warm, moist air moving in from the Gulf of Mexico and cool, dry air blowing in over the Rocky Mountains. A third source of air from the jet stream may wick away enough rain drops so that the lower air mass does not cool, and the warm air keeps feeding and intensifying a storm. As air moves in different directions and at different speeds, the whole storm will start to swirl, tending to pick up speed toward the center of the storm, eventually creating one or more funnels of rotating air.

Tornados are categorized based on the Enhanced Fujita scale from EF-0 to EF-5. This scale gives an estimate of wind speed and severity of damage inflicted. A little more than half of all tornados are found in the EF-0 range where wind speeds do not exceed 85 mph (137 kph) and damage is minor. Less than 1% of all tornados are recorded in the EF-4 (winds 166-200 mph) and EF-5 (winds over 200 mph) ranges. Another recent discovery is that most of the more severe storms tend to produce multiple tornados rotating around each other. Occurrences of multiple small funnels are difficult to observe within a large and often opaque mass of water, wind, and debris. This discovery helps to explain damages where one house may be completely destroyed while the neighbor is almost untouched.

The afternoon is the most likely time of day for these conditions to exist, once the sun has had a chance to heat the earth and air masses in the lower altitudes. In the Midwest, most tornados occur between noon and 8:00pm. Weather services are constantly monitoring conditions to be able to identify when weather patterns exist that may result in the formation of a tornado. Outside warning sirens are used by many municipalities to let people know that dangerous conditions are imminent. If you are hearing a warning siren, move inside and stay away from windows. Tune into radio, television, or internet resources to obtain the most up-to-date information for your area.

Beat The Heat

This week, the weather has been hot for the upper Midwestern U.S. with temperatures topping out above 100°F. Combined with high dew points in the mid-70s, the heat index temperature was upwards of 110°F. Here are some ways that plants and animals keep cool in the extreme heat.

^{Mojave Desert by LezusRocks, Getty Images}

^{Kit fox at entrance to desert den by Stevelenzphoto, Getty Images}

Desert environments, where hot conditions exist daily, are home to numerous animal species that live underground. Heat from the sun penetrates soils and sand layers for several inches, but at 20″ below the surface of the sand in the Mojave Desert, temperatures are fairly constant around 86°F while the surface may be over 110°F. Few large mammals are known to use burrows, although kit foxes and humans are two examples. Basements and lower levels in buildings are often preferred areas on hotter days.

^{Shaded walk in the woods by Felixmizioznikov, Getty Images}

Shade from trees is highly effective in creating cooler areas. Leaves are lighter in color than most soils and paved areas, and leaves reflect much of the sun’s radiation upwards, away from the shady area underneath. Denser foliage and rough leaf textures enhance the cooling effect. Under a shade tree, temperatures may drop up to ten degrees and other surfaces no longer exposed to direct sunlight, including our skin, may be 20 to 40 degrees cooler.

^{African elephant by Petr Polak, Getty Images: Black-tailed jackrabbit by Rancho_Runner, Getty Images; Fennec fox by Nattanan726, Getty Images}

Vasodilation occurs when blood vessels near the skin’s surface expand so more blood flows next to the skin. Many animals living in hotter climates, including fennec foxes, black-tailed jackrabbits, and African elephants, have large ears with broad, flat surfaces devoid of hair, fur, or other insulation. The ear’s large surface area is covered by a thin layer of skin and blood vessels. During hot weather, heat carried in the blood through the ear is readily lost to the outside environment, providing a cooling effect for the rest of the body.

^{Large crowd by Shaunl, Getty Images Signature}

Evaporative cooling is another method through which heat can be dissipated from a body. Trees use this method by losing water vapor through their leaves during photosynthesis, cooling the air under the leaves. Humans employ this method in a process called sweating. We lose warm water through skin pores directly to the air around us. Sweating also moistens our skin’s surface, indirectly providing additional cooling as air moves across the skins surface and wicks away additional heat. An important aspect enhancing the effectiveness of this method is our posture. Being supported by two legs, rather than four, exposes much less surface area to the direct rays of the sun, and much more surface area to air currents.

^{Forest path by Inga Nielsen, Getty Images}

While sweating is good for cooling, it is removing water from the body, which must be replaced for the process to continue. Exposure to today’s temperature extremes may result in a loss of three gallons of water or more from an average-sized human. As you are out enjoying nature during hot days, remember to keep hydrating to stay cool and keep other bodily systems healthy.

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.

Desert Habitat, pt.3

In the past two blogs, we have explored deserts and the plants which inhabit them. Animals native to these habitats have general adaptations for coping with temperature extremes, aridity, and finding water, food, and shelter. Strategies include hunting during cooler hours including at dawn, dusk, or overnight; obtaining water from sources other than standing water; burrowing underground to avoid temperature spikes and solar radiation; ability to conserve water in their body; ability to dissipate body heat; and being well-camouflaged. Look for each of these adaptations in the following species that live in our desert regions.

Greater roadrunner, Geococcyx californianus, by Tony Cyphert, Sep 2018

Ord’s Kangaroo Rat, Dipodomys ordii, by Andy Teucher, Jun 2005

The greater roadrunner, Geococcyx californianus, can only fly for several seconds at a time, but can reach speeds up to 17mph when running. They hunt early in the morning, retiring to shade when temperatures heat up mid-morning. Water requirements are met from foods including grass and prickly pear cactus, plus prey that includes lizards, scorpions, and rattlesnakes. Roadrunners do not urinate, but can excrete salt and save the water. They have an un-feathered area under their chins used to dissipate body heat. Ord’s kangaroo rat, Dipodomys ordii, is another species that gets all of their water requirements from the seed they eat. Individuals live in underground burrows, coming out only at night to feed. They conserve water in their bodies and do not sweat or pant. They have many predators, but with a 9-foot jump and excellent hearing, they are hard to catch. Seeds are collected and stored in their burrows, and they will gain 50% more water from the underground humidity before being eaten.

Horned Toad, Phrynosomasp., by TJFrom AZ, May 2009

Gila monster, Heloderma suspectum , by Karla Kishinami, Apr 2012

Horned toads, Phrynosoma spp., are small, ant-eating lizards with thick scales to conserve water and deter predators. To escape a predator, these animals can squirt a directed stream of blood from their eyes up to five feet away. They are sandy-colored with undefined outlines allowing them to easily hide amid rocky outcrops. Normally active during the day, they can retreat to burrows or under rocks if temperatures become too hot. During winter, horned toads will spend a period of inactivity, called brumation, in underground burrows. The Gila monster, Heloderma suspectum, is another lizard with armor protected skin marked with black and pink coloration that camouflages them well in sandy soils. They shelter from daytime heat under rocks and shrubs, emerging in early morning or evening to hunt small mammals, lizards, insects, and bird eggs. One of only two venomous reptiles in North America, their venom adversely affects their prey’s nervous system. The short, thick tail stores water in fatty tissue for use when needed.

Tarantula, Aphonopelma sp., by Saguaro National Park, Nov 2020

Western coral snake, Micruroides euryxanthus, by Ashley Wahlberg, Apr 2016

The tarantula, Aphonopelma spp., shelters in deep burrows lined with silk to prevent the sand from caving in. They are nocturnal hunters of insects, arthropods, and small lizards with a bite that delivers a small amount of venom to stun their prey. Venom immediately starts to break down tissue to liquify the meat, allowing the spider to use sucking mouth parts to draw in its meal. The Western coral snake, Micruroides euryxanthus, is brightly colored with red-white-black-white banding and venom that is twice as deadly as most rattlesnakes. They are very secretive, living under rocks or buried in the sand. Coming out at night or on some overcast days, they hunt for lizards and other snakes. Venom causes rapid paralysis and respiratory failure, although due to their small size and small amount of venom injected, they are not a threat to humans.

Like many environments, a healthy desert community exists when plants, animals, and habitat are all present and undisturbed. With much of the life in deserts underground, walking off trails and driving off roads can negatively impact what is under the surface. Removing plants and rocks used for water and shelter is equally damaging. I encourage you to get out, observe, and enjoy this unique habitat, or research many of the fun and interesting adaptations at a local natural history museum.

^{Pictures above clockwise: Bark scorpion by Josh More, May 2014; Cactus wren by Mick Thompson, Feb 2019; Jackrabbit, by Mark Gunn, Mar 2014; Javelina, Sonora Desert, by Richard Bonser, Jan 2005; Tarantula hawk wasp by Jim Mulhaupt, May 2010; Sonoran mud turtle by Grigory Heaton, Sep 2022; Round tailed ground squirrel by Wendy Miller, May 2022; Hoary bat by Michael Pennay, Sep 2009; Cactus deermouse by J.N.Stuart, Oct 2011}

Desert Habitats, pt.2

Pequop Mountain foothills, Great Basin Desert, Nevada by Matthew Roth, Apr 2016

Big sagebrush, Artimesia tridentata by RCWinton, Aug 2008

There are four major deserts in North America. The Great Basin runs from central Idaho to northern Arizona. It is a high altitude plateau, with very cold winters, mild summers, and few plant species characterized by big sagebrush, Artimesia tridentata.

The Mohave Desert, a small area covering southern Nevada and southeastern California, is known for its cold, rainy winter season resulting in hard freezes leaving little water available. The Joshua tree, Yucca brevifolia, a yucca variety growing above 3000′, is the tallest plant in the area.

Joshua tree, Yucca brevifolia, by Melissa Delzio, May 2011

The Chihuahuan Desert, covering the high altitudes of northern Mexico ,is subject to hard freezes from arctic winds scouring its surface. Winter rains occasionally occur supporting a rich diversity of low shrubs and small cacti.

The Sonoran Desert, covering southern Arizona and the Baja Peninsula, has high and low altitudes, hot to mild temperatures, and periodic rainfalls. The winter season, with mild temperatures, does not limit the plant and animal diversity as much as in the other three, colder deserts. The Sonoran Desert, which includes several habitat types, supports a rich variety of species including 2000+ plants, 350+ birds, 100 reptiles, and 30 native fishes.

Desert plants exhibit many similar features that make them well-adapted to the hot, dry conditions of their native habitat. Most are succulents, plants with thick, fleshy stems to retain water for use during hot, dry periods. Plants often have spines in place of leaves to reduce the surface area exposed to wind and heat, greatly reducing water loss from evaporation. Spines also add a layer of protection to prevent animals from eating the plant. Stems are green, containing chlorophyll and water, and this is where photosynthesis takes place. Bloom periods and pollination occur during winter or nighttime when cooler temperatures prevail.

Creosote bush, Larrea tridentata, in flower by Malcom Manners, Apr 2017

Century plant, Agave americana, by J.Maughn, Mar 2020

Several distinctive native species characterize North American deserts including cacti, succulents, and other plant varieties with spines. The creosote bush, named for its distinctive antiseptic smell, grows three to nine feet tall and has small yellow flowers. This plant grows in colonies of cloned bushes which may live for long periods as epitomized by the King Clone of the Mohave Desert, estimated to be about 12,000 years old. The century plant, another long-lived plant, is a species of agave noted for its large cluster of wide leaves with spiny edges. The plant may live up to 30 years, but flowers only once, then dies.

^{Clockwise from top: Prickly pear by Fishfoot, Mar 2018; Prickly pear buds by Diandra Rodriguez, Nov 2011; Prickly pear cacturs in bloom by Stepan Mazurov, May 2009; Prickly pear cactus glochids by Tracie Hall, Nov 2017}

Often seen cacti include the prickly pear cactus which is actually a group of several species all native to North America. Modified stems, called pads, are often mistaken as leaves. These store water, photosynthesize food and sugars, and produce flowers. All species grow long, single spines in addition to glochids, clusters of very fine, tiny spines. Glochids are often not noticeable but can be easily detached if brushed against and once lodged in the skin are painful and difficult to remove. The saguaro cactus is another common plant. Its distinctive shape, with a tall central column and “arms” growing at right angles, is easily recognizable as one of the Sonoran Desert’s native species. It is the largest cactus in North America, growing to over 40′ high, and living 100 years or more. White, waxy flowers open only at night to attract bats, its preferred pollinator.

Saguaro cactus by Ralph Earlandson, Apr 2017

Many natural history museums have excellent displays of plants and animals from world-wide desert biomes, including one of my favorites, the North American desert display at the Jurica-Suchy Nature Museum. In my blog next week, I will introduce some of the notable animals and their adaptations to desert life.

Desert Habitat, pt.1

A biome is a type of global habitat characterized by temperature, rainfall, latitude, elevation, and wind pattern. Plants, which are unable to move about, are used to characterize each type of biome, and are well-adapted to their native habitat. The desert biome is the driest habitat found on earth. In a desert, plants are widely spaced and are adapted to life with little or no moisture except for annual periods when brief rains may be heavy, sparse, or not occur at all. Even within these harsh conditions, plants may be present supporting a rich diversity of species.

_{Clockwise above: Hidden Valley, Joshua Tree solitude by Don Graham, Apr 2013; Sonoran Desert sunset by Jasper Nance, May 2009; Sonoran Desert layers by Art DiTommaso, Apr 2020; Mohave Desert by Melissa Delzio, May 2011}

A common factor of all deserts is the aridity or lack of moisture. Aridity can be determined by how much water is available in the habitat combined with the rates of evaporation from heat, radiation, and wind exposure. Another consideration in determining aridity is how much moisture the air can hold. Neither extremely hot nor extremely cold air easily retains moisture. Freely running water is only available in the desert for the briefest period of time immediately following a rainfall, a scarce and unpredictable event.

Deserts form in areas where dry air predominates. Understanding how weather influences the Earth’s surface helps to identify where to find the world’s desert regions. At the equator, air is warmed by direct sunlight causing it to rise and absorb large amounts of water from the oceans. When the warm air mass encounters cooler air at higher altitudes, it spreads out both northward and southward. Cooler air causes the absorbed moisture to condense into rain in tropical latitudes. The outward moving air mass, now dryer and cooler, also begins to fall back to the earth’s surface, picking up heat from the sun’s radiation and the hot ground. Air masses generally descend and move back towards the equator around 30˚ latitude, which is where many deserts occur.

Rain shadow on leeward side of mountains on Oahu by Loren Javier, Jun 2010

Exploring Greenland’s grass and Dry shrub vegetation by Eugene Kaspersky, Jul 2016

Deserts can also be formed from rain shadows and temperature extremes. As prevailing winds encounter mountains, air is forced up the windward side and flows down the leeward side. As air rises, it cools, once again condensing any moisture into rain which falls on the windward side. Dry air coming over the mountain forms a rain shadow that leaves little moisture for the habitats on the leeward slopes. Temperature extremes occur in both hot and cold regions. Dry, hot air descending from the tropics form warm deserts. Cold, dry air from polar winds form cold deserts such as those found in Antarctica and Greenland.

Desert temperatures vary widely, both daily and seasonally. Dry air and cloudless skies allow a maximum amount of solar energy to reach the surface where it is absorbed and converted to heat, raising daytime temperatures dramatically. At night, air temperatures plummet as solar radiation ceases and heat is quickly wicked away into the cooler atmosphere. Temperatures may fluctuate as much as 100˚ in a 24-hour period. Ultraviolet radiation also presents other challenges to living organisms. Intense sunlight can damage skin cells, degrade retinal tissue, and destroy chlorophyll molecules in plants.

Rain in the Sonora Desert summer monsoon season by Kevin, Aug 2013

Green Sonoran Desert after brief winter rain by Wayne S. Grazio, Fwb 2017

Deserts experience seasons, just as those found in other biomes. In desert areas of Arizona, there are five recognized annual seasons. Spring, February through April, is characterized by mild temperatures and windy days. It is a dry season as warm winds wick away all exposed moisture. Summer, in May and June, is hot and dry, with many species remaining dormant to escape the heat. Summer monsoons, July through mid-September, signals a change in wind direction bringing moister air northward from the tropics. Frequent thunderstorms occur most years providing a period of replenishment for shrubs and trees. Autumn, in October and November, returns to warm and dry conditions. Winter comes in December and January bringing in mild temperatures and the possibility of a few rain showers.

The climate of the world’s deserts makes survival difficult, but many species have adapted to these conditions in some remarkable ways. Next week, we will investigate the desert regions of North America and their vast diversity of life.

_{Clockwise above: Blooming hedgehogs by Jasper Nance, Apr 2010; Desert globemallow by Take-A-Hike Arizona, Mar 2009; Desert woollystar, Eriastrum eremicum, Sonoran Desert by SSBiker1, May 2011}