Ever wondered what goes on in the Greater Yellowstone Ecosystem after you tuck into your cabin or tent at night? There is still plenty of activity! Many wildlife species are ‘crepuscular’ meaning they are most active at dawn and dusk – this is one reason Wildlife Expeditions of Teton Science Schools provides sunrise and sunset tours: so our guests get the best possible chance to see amazing wildlife activity at peak times! Keep reading to learn more about three fascinating nocturnal and crepuscular species you might be lucky enough to catch a glimpse of on your trip with Wildlife Expeditions.
Mountain lions
Though seldom seen, mountain lions are both fascinating and important parts of the GYE. While you may get lucky and glimpse a mountain lion during the day, they are most active at dawn and dusk, when deer and other prey are most active (National Park Service). While they are generally solitary, mountain lions have a larger impact on their environment than you might think. A 2023 study led by Panthera program director Mark Elbroch discovered that mountain lions in the Greater Yellowstone Ecosystem are ‘ecosystem engineers’, meaning they “create new habitat for species to live in.” (Wyoming Public Media)
Mountain lions primarily prey on elk calves and mule deer, but may go after a moose if the opportunity arises. They also catch small mammals including marmots, squirrels, grouse, and porcupines. Unlike other predators like bears and wolves, mountain lions cache their kills, and come back to them for 3-4 days (Yellowstone National Park). The study by Panthera found that because mountain lions only eat about a third of the carcasses from their prey, the rest is left for other scavengers and contributes positively to the ecosystem. In addition to wildlife we might expect to see at a carcass, such as vultures, bears, wolves, and eagles, these carcasses receive unexpected visitors like mice, flying squirrels, woodpeckers, and chickadees. These mountain lion carcasses feed 215 species of beetles! According to Elbroch, “Pumas contribute over a million kilograms of meat to ecosystems every day, improving the quality of soil and plant life, feeding hundreds of species, and supporting the health of their ecosystems and our planet’s overall web of life.” The decomposing carcasses also add nitrogen to the soil, which improves plant growth, and therefore improves forage for ungulates (like elk, deer, and moose). And, healthier ungulates are then better food for mountain lions.
Red foxes
Red foxes are the smallest canids in the GYE, known for their distinctive red fur and white-tipped tails. While visiting Grand Teton National Park, you may see a fox that is not red and wonder “what kind of fox is that?” In the GYE, red foxes can be ‘melanistic’ or partially melanistic, ranging in color from red to black to a combination of red and black. (Yellowstone National Park)
These creatures are primarily nocturnal, but they may become more active during the day, especially in winter. While they prefer forested habitats, they can also be found in sagebrush and grassland areas. In Yellowstone, you can reliably find red foxes in the Hayden and Pelican Valleys and Canyon Village.
Bats
At Wildlife Expeditions, we want you to say “sweet!” instead of “eek!” when you see a bat. Yellowstone National Park is home to a diverse bat population, consisting of 13 distinct species. Like humans, bats are mammals and require warm environments for roosting (ok, humans don’t usually roost, but you get the point!). These cozy roosts are essential for raising young bats, allowing them to grow quickly and become independent foragers. Bats often seek refuge in natural structures like caves but also utilize man-made structures such as bridges, and buildings, and abandoned mines. The NPS has found that access to building attics is crucial for the reproductive success and conservation of Yellowstone’s bat population.
To navigate and find food in the dark, bats employ echolocation. By emitting high-frequency calls, they can locate prey – for Yellowstone bats, this is insects – with remarkable precision. During the summer, female bats nursing pups can consume an astonishing amount of food, often equaling their own body weight in a single night. Bats also communicate with each other using low-frequency calls, some of which can be heard by humans. These adaptable creatures are skilled at regulating their body temperature, entering a state of torpor (lowered body temperature and metabolic rate) during periods of food scarcity or extreme cold. Their ability to hang upside down for extended periods aids in predator avoidance and helps bats fly away more easily.
Join Wildlife Expeditions for a sunrise or sunset tour! Our knowledgeable guides will lead you to prime viewing locations, offering a glimpse into the captivating world of Yellowstone’s wide variety of wildlife. Remember, with a little patience and a keen eye, you might just be lucky enough to spot one of these fascinating creatures in their natural habitat.
Sources:
- https://www.wyomingpublicmedia.org/natural-resources-energy/2023-05-09/a-new-study-finds-mountain-lions-might-be-changing-the-greater-yellowstone-ecosystem-for-the-better
- https://www.nps.gov/yell/learn/nature/cougar.htm#:~:text=Yellowstone%20biologists%20use%20remote%20cameras,;%2050%25%20survive%20first%20year
- https://www.nps.gov/articles/mountain-lion-safety.htm#:~:text=Mountain%20lions%20are%20solitary%20animals,dusk%2C%20corresponding%20with%20deer%20activity.
- https://www.nps.gov/yell/learn/upload/8_RI_2024_Wildlife.pdf
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Notes
- There are 13 bat species in Yellowstone alone! Like you and I, bats are mammals, and also like you and I, they want a warm place to rest. A warm roost also allows young bats to grow faster and forage for themselves earlier. Bats roost in caves and other natural structures, as well as manmade structures such as bridges, buildings, and abandoned mines. According to the NPS, “research suggests that access to building attics within Yellowstone National Park is critical for their reproductive success and long-term conservation.”
- Bats use echolocation to find food and navigate in the dark. High frequency calls are used to locate prey – for Yellowstone bats, all of which are insect-eaters, this means BUGS. During the summer, a female bat nursing a pup can eat her entire body weight in insects each night. Low frequency calls, some of which humans can hear, are used for bat-to-bat communication.
- Bats are excellent thermoregulators (regulating their body temperature) and can enter ‘torpor’, a state of lowered body temperature and metabolic rate. “Most bat species in Greater Yellowstone undergo torpor that may continue for months and is typically a seasonal response to a prolonged drop in temperature or reduction in food supply.” (NPS)
Why do bats hang upside down? Roosting upside down allows bats to fly away more easily and avoid predators. They are able to hang upside down for months at a time! “…cavities in [their] craniums pool blood and other fluids away from the brain and…an arrangement of ligaments and leg muscles enables them to hang passively from their perch while sleeping.” (NPS)
