Ever heard of a Hibernaculum?

Northern snakes, such as Garter species, Red-bellied Snakes, and Fox Snake migrate to what is called a hibernaculum (or hibernation site) every winter. Snakes may travel up to two miles to their hibernation site, which is usually the same den used for hibernating in previous years. Snakes can hibernate in aggregations - hundreds of snakes gathering in the same hibernaculum, spending the winter together and accessible to each other for spring breeding. During the winter, temperatures in the hibernaculum never drop below 37-39 F at which snakes may safely remain for about sixteen weeks without serious loss of body weight or impact on general health. One of the ways they are able to sustain such dormancy is to stock up on body fat by feeding heavily during the late summer.

When spring weather arrives, the hibernaculum may take two or more weeks to warm up. During this time, the snakes slowly come awake, some making short forays outside the den, returning to the hibernaculum for the night to avoid the still-cold spring night temperatures above ground. This feature helps ensure they will not be caught out during a late frost.

This February WINC received several snakes from a family who had found a hibernaculum in their window well. Some construction had happened to disturb the hibernaculum forcing several snakes to be noticed in their window well. Since the snakes were woken up and trapped in the window well, the family was advised to bring any snakes they had found into the center. Releasing the snakes would have killed them, as they could not survive the temperatures without the help of the hibernaculum. The family brought a total of nine snakes (three Red-bellied Snakes, three Common Garter Snakes and three Eastern Plains Garter Snakes) in for us to overwinter until spring.

To our surprise two of the Garter snakes give birth to baby snakes before spring was here! One of the Eastern Plains Garter snakes had 27 babies and one of the Common Garter Snakes had nine babies! Soon the snake corner in the clinic was known as Snake City as the population had grown drastically! Feeding time became a two person job as several baby earthworms would be placed in with the babies and staff would have to watch for babies would eat and then place them back in with their mother. After two weeks it was finally nice enough to release the snakes.

We called the family and explained that the number of snakes had multiplied three-fold! They were more then happy to get all the snakes back onto their beautiful large property, which was a relief because snakes should always go back to where they came from. Snakes’ home ranges are usually quite small, so placing them somewhere that they are not familiar with can be very detrimental. 

On April 29, 2011 we released a total of 45 snakes back to the wild! It was a unique experience caring for the baby snakes – an experience that staff and volunteers won’t ever forget!

Guest Blogger, M.F.