by Rebecca Michelin
How do you prepare for winter? Check your home for drafts, make sure your heaters work, and stock up on hot chocolate!
Wild animals all cope with the approaching cold in different ways: Every species experiences seasonal changes differently, and the cues that signal animals to start their winter preparations vary widely. In our upcoming articles, we will discuss some of the challenges that face wildlife at this time of year, starting with hibernation.
Hibernation is a complicated subject, and there is no one-size-fits-all answer. Some species hibernate, some enter torpor, and some don’t hibernate at all but stay active through even the coldest temperatures. Here are answers to two common questions about hibernation:
I found a bat on the ground in December – shouldn’t they be hibernating by now?
With the recent sudden drops in temperature, the Wildlife Clinic at the Schuylkill Center received over a dozen calls about bats in just three days.
The six species of bats that stay in Pennsylvania year-round are true hibernators; they eat enormous amounts of food during the warmer months then sustain themselves by burning body fat through the winter when their food source, insects, is not available. True hibernators drop their body temperature and reduce their metabolic rate to such a low level that they are difficult to rouse, which allows them to use as little energy as possible to stay alive.
Bats don’t suddenly fall asleep as soon as it gets cold, however. Daylight hours, availability of food and mating activities can all affect when a bat enters hibernation. Rapid changes in temperature or a series of warm days with very cold nights can catch some bats off-guard; a season where insect numbers are low may mean that bats are still trying to fill up and build fat stores late into the fall.
Anytime a bat is found exposed or on the ground at this time of year, they are probably in need of help; bats that are still active when temperatures are low are burning precious fat stores that they need to survive the winter. Remember: Bats are potential carriers of rabies! Never touch them with your bare hands, and always talk to a rehabilitator before taking any steps to help a bat.
I was working in my garden and accidentally dug up a box turtle/toad/frog. Can I just leave him outside so he can go back to sleep?
Brumation is the term for hibernation in cold-blooded animals. Very generally, the difference is cold-blooded animals cannot actively drop their own body temperature and control their dormant period – instead, they are entirely dependent on external temperatures. Reptiles and amphibians will usually choose a specific area like soft soil or mud, woodpiles or leaf debris to bury themselves in and will stay there until warm weather arrives in spring.
If a turtle or frog is caught outside their home, they may not survive a sudden temperature drop. Similar to bats, anytime they are disturbed during hibernation they have to expend a large amount of energy to maintain body functions while awake, which can deplete their energy stores, meaning they may starve before spring. Reptiles and amphibians will also not survive hibernation if they are sick or injured, as their immune systems and body functions are so slow they cannot heal.
If you accidentally disturb a hibernating reptile or amphibian, quickly check for injuries – if they are not hurt and their hibernation home is still intact, you can return them to the exact spot they were found and make sure they are well covered as they were before. If they are injured or their home was destroyed and they can’t be returned, they should be brought immediately to a wildlife rehabilitation center.
In our next article, we will focus on how young animals born in the spring and summer prepare to face their first winter. If you have wildlife questions you would like answered, please submit them to firstname.lastname@example.org. If you find an injured or orphaned animal in need of assistance, please call the Wildlife Clinic at 215-482-7300, option 2.
Rebecca Michelin is the Wildlife Rehabber at the Schuylkill Center for Environmental Education.