Category: Mammals

Posted on

Wily Coyotes

Coyote Canis latrans
Photo Courtesy & Copyright © 1991
Eric Gese, Photographer

Coyote Canis latrans
Photo Courtesy & Copyright © 1991
Eric Gese, Photographer

In many of the diverse Native American storytelling traditions, the coyote plays the same role over and over: that of the smart, sly trickster. For those who study coyote behavior, this characterization is well deserved. Coyotes are incredibly adaptable creatures – intelligent, observant, curious and well, wily.

Their ability to adjust how they live to fit their circumstances can be seen in almost every aspect of the coyote’s life. For starters, coyotes will eat just about anything. As omnivores and opportunistic feeders, coyotes might be found hunting creatures as diverse as small mammals, birds, snakes, mule deer fawns, insects, or fish, and also seek out grasses, berries and seeds. They can hunt alone or in packs, and are not below feasting on carrion, rummaging through your garbage, or raiding the cantaloupe patch.

The environments in which coyotes can be found are similarly diverse. While once restricted to the American West, coyotes are now widespread across all of North America and parts of Central America, and can be found in nearly every ecosystem from deserts to forests to urban areas from Belize to Alaska.

Sometimes called ‘song dogs’ these social creatures are known for their nighttime solos and choruses. Their scientific name, Canis latrans literally means ‘barking dog’, and their many vocalizations help pack members and families bond and communicate over long distances. Coyotes have strong family ties, especially during spring, when puppies are born to monogamous coyote couples.

Coyotes are territorial and defend their space vigorously – especially when breeding and denning. Mating occurs from January through February and after a gestation period of only 60 to 62 days, 3 to 12 pups are born blind and helpless in March or April. Young coyotes are nursed for 4-5 weeks at which point they transition to regurgitated meals brought by both parents. Youngsters tag along on family hunts at 8 weeks old and are able to hunt independently by fall.

Interestingly, studies have shown that even coyote breeding is adaptable – a phenomenon called ‘density dependent reproduction’. In areas where coyote populations are stable, females bear lower numbers of pups. But in areas where there is disturbance to the population – for example through increased predation or hunting – females have larger litters. On average, newborn pups have less than a 50% chance of surviving to adulthood due to threats from disease, predators, and starvation. It therefore makes sense for females to bear more offspring in areas where threats may be even greater.

To learn more about coyote adaptability, join the Stokes Nature Center for a tour of the USDA/National Wildlife Research Center Predator Research Facility on June 16th. For more information visit www.logannature.org. Thank you to the Rocky Mountain Power Foundation for supporting the research and development of this Wild About Utah topic.

For the Stokes Nature Center and Wild About Utah, this is Andrea Liberatore.

Credits:
Images: Courtesy and Copyright © Eric Gese
            National Wildlife Research Center, Predator Behavior and Ecology
Text:     Andrea Liberatore, Stokes Nature Center in Logan Canyon.


Additional Reading:

Stettler, Brett. 2009. Coyote (Canis latrans). Utah Division of Wildlife Resources Wildlife Notebook Series No. 19. Found online at:
https://wildlife.utah.gov/publications/pdf/2010_coyote.pdf

Video: Coyotes Cruise NYC, Science Friday & Mark Weckel, https://www.sciencefriday.com/videos/watch/10444

Posted on

Sleeping the Winter Away

Click to view larger image of male Black Bear, Photo Courtesy US FWS, Mike Bender, Photographer
This Black Bear will retain heat
much better during hibernation
because it has a larger body
compared to the area of its outer
surface and it has thicker fur
compared to smaller animals
Photo Courtesy US FWS
Mike Bender, Photographer

Click to view the Mountain Chickadee, courtesy and copyright Stephen Peterson
Mountain Chickadee
Even though some small birds, like chickadees, may enter torpor,
they use almost all of their
energy stores each night.
Courtesy & Copyright
Photographer: Stephen Peterson

Hi, this is Mark Larese-Casanova from the Utah Master Naturalist Program at Utah State University Extension.

While I’ve mentioned how certain animals are well adapted to being active in winter, some choose to save their energy and sleep the winter away. Maintaining a constant body temperature in winter, when air temperature is relatively low, can require consuming great amounts of energy stores, such as fat. This can be especially difficult during a time of year when food is scarce.

Smaller animals especially struggle with heat loss because, relative to their body size, they have much more surface area from which they can lose heat. Compare a mouse to a bear- the bear will retain heat much better because it has a larger body compared to the area of its outer surface. Not to mention, a bear’s fur is much thicker than that of a mouse!

For certain animals, it makes sense to lower body temperature while being inactive so that they can conserve as much energy stores as possible. This can happen in several different ways. Sleeping for part of a daily cycle can conserve a little energy since body temperatures drop slightly during sleep. If air temperatures are particularly low and food is scarce, some animals will enter torpor, allowing their body temperatures to drop closer to air temperatures in order to save even more energy. An animal can be in torpor for just a night, or perhaps a few days. If it is able to store enough energy reserves and can survive a decrease in body temperature for longer periods, some mammals may enter deep torpor and hibernate for several weeks or months in the winter. During this time, the rate of energy consumption is just a small fraction of what it might normally be when the animal is active.

Body size and energy stores influence just how inactive an animal can be in winter. Some of our smallest mammals, such as shrews and mice, lose heat so readily and can store so little fat that they cannot afford to hibernate. They must always find food in order to survive. Even though some small birds, like the black-capped chickadee, may enter torpor, they use almost all of their energy stores each night. If they fail to replenish their fat reserves each day, they might not survive.

The true hibernators are the mid-sized mammals. While ground squirrels, jumping mice, and bats may hibernate for much of the winter, they occasionally wake up for a day or two of activity. Even larger mammals, including raccoons, skunks, and bears, don’t actually need to hibernate. Their body temperature drops just a little, and they are able to survive on their stored fat simply by sleeping.

So, while I sometimes envy the true hibernators on some of those cold winter days in Utah, I’m still thankful that I can adapt to winter and enjoy our great outdoors year-round.

For Wild About Utah, I’m Mark Larese-Casanova.

Credits:

Images: Courtesy US FWS and Stephen Peterson, Bridgerland Audubon Society

Text:     Mark Larese-Casanova, Utah Master Naturalist Program at Utah State University Extension.
Additional Reading:

Heinrich, B. (2009). Winter world: The ingenuity of animal survival. Harper Perennial.

Eckert, R., D. Randall, and G. Augustine. Animal physiology: Mechanisms and adaptations. W. H. Freeman and Company.

 

 

Posted on

The Shape of Wildlife in Winter

The Shape of Wildlife in Winter: Short-tailed weasels, also known in winter as ermine, have a long, slender body shape that allows them to invade subnivean tunnels to prey upon smaller mammals.
Short-tailed weasels, also known in winter as ermine, have a long, slender body shape that allows them to invade subnivean tunnels to prey upon smaller mammals.
Photographer: Steven Hint
Courtesy Wikimedia
Licensed under Cc-by-sa-3.0

Hi, this is Mark Larese-Casanova from the Utah Master Naturalist Program at Utah State University Extension.

Now that snow is finally accumulating in Utah’s mountains, weekend hiking trips have come to an end. But, that means it’s time to dust off the snowshoes and skis and get back outside. We humans are lucky in that we have countless types of gear to help us adapt to almost all winter conditions.

While a fur coat might help keep mammals warm or camouflaged in winter, there are many other adaptations that also aid in winter survival. Decreased mobility in deep snow can often prevent animals from finding food, possibly causing starvation in winter.

Some animals have feet that are particularly large for their body size, which helps them travel on top of deep snow. One of the best examples of this adaptation can be found in snowshoe hares. Snowshoe hare prints are easy to spot among the spruce and fir trees- the large teardrop-shaped hind feet leave prints that look like the hare was wearing miniature snowshoes, which is how it got its name.

While some animals are adapted to walk on top of deep snow, others do their best to simply walk though it. The long, slender legs of moose help keep the majority of their bodies above the snow, minimizing the energy required to travel in winter.

Instead of walking on top of or through the snow, small mammals such as mice and voles travel under the snow. As snow accumulates, mice and voles create vast networks of tunnels on top of the ground, but under the snow. This subnivean environment is typically warmer than air temperature above the snow, and still provides access to food, such as grasses, seeds, and bark.

Short-tailed weasels, also known in winter as ermine, have a long, slender body shape that allows them to invade subnivean tunnels to prey upon smaller mammals. As long as its head can fit into a tunnel, its narrower body can follow. This adaptation comes with a price, though. Slender bodies lose heat quickly, so weasels must consume around one-third of their body weight in food each day in order to produce enough heat to survive.

So while deep powder might seem like a winter wonderland to those of us who can adapt with the right gear, other mammals continually struggle to stay warm and find food. Some, however, choose to give up the fight and sleep the winter away.

For Wild About Utah, I’m Mark Larese-Casanova.

Credits:

Images: Pending rights approval
Text:     Mark Larese-Casanova, Utah Master Naturalist Program at Utah State University Extension.
Additional Reading:

Ellsworth, E. Surviving the winter: The importance of snowshoe hare foraging behavior. BEHAVE: Stories of Applied Animal Behavior. University of Idaho. Available at: https://www.cnr.uidaho.edu/range556/appl_behave/projects/hare_forage.html

Gellhorn, J. (2002). Song of the alpine: The Rocky Mountain tundra through the seasons. Johnson Books.

Lieberg, A. (2009). Charismatic minifauna. Northwest Connections. Available at: https://www.northwestconnections.org/documents/news/EOE_09feb26_Lieberg.pdf

Posted on

Cache and Retrieve

Click for a larger view of the Clark's Nutcracker, Nucifraga columbiana, Image licensed through the noted CCL. Stephen Pavlov, Photographer
Clark’s Nutcracker
Nucifraga columbiana
Courtesy Steven Pavlov
This file is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license 

Common Raven
Corvus corax
Courtesy US FWS
Gary M. Stolz, Photographer 

Hi I’m Holly Strand.

Every year, just before Christmas, I comb through the house looking for presents hidden earlier in the year. I check inside old shoes, unfold towels in the closet, and peer way back into the dark recesses of seldomly-used cabinets. With a child in the house, you have to be tricky! The problem with this complex gift stashing behavior is that sometimes I forget where I hid the present when it’s time to wrap it! And once in awhile I forget that I bought something at all! Out of sight—out of mind!

You wouldn’t make a very good magpie, I have been told. For magpies– along with jays, crows and ravens, are masters at hiding–or caching as it’s called– and then retrieving. Of course, what they cache is not Christmas presents but food.

One Utah bird that is much admired for its caching and retrieving skills is Clark’s nutcracker . This large jay lives in mountainous areas throughout the west. Experts say that Clark’s nutcracker can cache 10s of thousands of pinyon, whitebark or limber pine seeds in a single season. Starting in August, the bird will hide 1-15 seeds at a time, often distributing them several kilometers and at much different elevations from the original tree. Caches lie 1-3 centimeters deep in forest litter, bare soil, under bark, in holes, in logs or stumps.

As winter wears on, the nutcracker will retrieve its caches with the help of visual landmarks such as rocks, trees or logs. Using these visual cues, the nutcracker will retrieve the seeds through summer of the following year. Forgotten or abandoned seed caches often germinate, growing into trees that produce more food.

Just as I worry about prying eyes when I hide Christmas presents, birds who cache must be careful to notice who is watching. The common raven is notorious for its spying and thieving behavior. One raven will covertly observe while another caches scraps of meat, eggs, bones or seeds. The observer will then shamelessly raid the cache usually within a couple of days. But having probably raided someone else at some point, the caching raven is on the lookout too. If the caching raven senses the presence of a would-be looter, it might wait for the other bird to become preoccupied. Or it may move the food to a different site altogether. Caching ravens will also hide behind some structure to avoid being seen.

Interestingly, these sly birds will even engage in fake caching. Ravens will cache inedible or low value food items in plain view of other ravens but then stash the good stuff in secret. Fake caching seems designed to throw looters off track, . But perhaps it’s also a character test for fellow ravens? Or maybe—for the intelligent raven—it’s all just an amusing shell game?

For sources and pictures for this and past stories, go to www.wildaboututah.org

For Wild About Utah, I’m Holly Strand.

Credits:

Theme: Courtesy & Copyright Don Anderson as performed by Leaping Lulu
Images: Courtesy Wikimedia/ Steven Pavlov, Photographer
and Courtesy US FWS, Gary M. Stolz, Photographer
Text & Voice: Holly Strand

Sources & Additional Reading:

Balda, R.P. & Kamil, A.C. 1989. A comparative study of cache recovery by three corvid species. Animal Behaviour 37: 486-495. https://doi.org/10.1016/S0003-3472(89)80041-7

Boarman, W. I. and B. Heinrich (2020). Common Raven (Corvus corax), version 1.0. In Birds of the World (S. M. Billerman, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.comrav.01 or https://birdsoftheworld.org/bow/species/comrav/cur/introduction

Bugnyarf, Thomas and Kurt Kotrschal. 2001. Observational learning and the raiding of food caches in ravens,Corvus corax: is it ‘tactical’ deception? Animal Behavior, Volume 64, Issue 2, August 2002, Pages 185–195. https://doi.org/10.1006/anbe.2002.3056

Heinrich, Bernd and John W. Pepper. 1998. Influence of competitors on caching behaviour in the common raven, Corvus corax . Animal Behaviour. Vol. 56, 1083–1090, https://doi.org/10.1006/anbe.1998.0906

Marzluff, John and Tony Angell. 2005. In the Company of Crows and Ravens. Yale University Press. https://yalepress.yale.edu/yupbooks/book.asp?isbn=0300100760

Schaming, T. D., D. F. Tomback, and T. J. Lorenz (2024). Clark’s Nutcracker (Nucifraga columbiana), version 2.0. In Birds of the World (N. D. Sly, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.clanut.02 or https://birdsoftheworld.org/bow/species/clanut/cur/introduction

[Page Updated February 12, 2026]