With the first few nights of brisk temperatures that come in September, animals make a dramatic change in their habits. Some species hibernate, some species remain active all winter, and some species simply slow down but do not truly hibernate.

The work we do changes greatly between late summer and late fall heading into winter. For the species that hibernate, we stop doing work for them completely until they emerge, usually in and around late march/early may for most species.

If you were dealing with animals in the fall that go into hibernation, once you hit the cutoff in weather you can no longer evict them until spring. These types of animals are bats, groundhogs, and all reptiles including snakes, frogs, and turtles (“brumation” as opposed to hibernation). There are 3 main categories you can break the winter changes for wildlife into - Hibernation, Torpor, or Active. Every animal around here does one of these.

There is some slight overlap when discussing these. For instance, if a bat or snake finds its way into a structure for hibernation, that structure may stay warmer than they are used to in the winter, and they may not totally go into their full hibernation state (breathing slowing way down, activity almost non existent). So depending on their winter setup, there can be some debate in a case by case basis, but in general the species listed fall into these groups.

Length of these hibernation and torpor states varies based on where you are in the country and how long your winters are. Here in Western Massachusetts, we see these happen between about mid October and Mid April.

In New England, only a few species remain mostly active for the winter. During periods of less cold, the animals that are slowed in their torpor state may become moderately active until temps fall again.