How to Build a Snake Hibernaculum

I’ve been watching one of those animal shows today and they were talking about snakes. At one point they showed a hibernaculum of garter snakes leaving in the Spring. Made me think about how we could encourage garter snakes or at least help them to survive by having something like that in our garden. I’d also like to build a bat house to encourage more of them too. We used to get a lot when we lived in Alliston. They eat a ton of bugs and only come out for about an hour just as the sun is going down. All the rumours about them being dangerous are a bit overdone. They may have rabies true but that is the extent of the danger.

Meanwhile, back to the garter snakes. I found information about building a snake hibernaculum on the Toronto Zoo website. I don’t know if my Mom would be interested. Not that she is afraid of snakes at all but her garden space is mostly spoken for with all the plants she already has and those she is more than likely to find to add during the garden season.

Would you build a winter home for snakes? In Ontario we don’t have to worry much about poisonous snakes or any other kind of poisonous creature really. Rabies are a bigger worry.

How to Build a Hibernaculum
1. Select a well-drained site protected from cold winds, with good sun exposure (south-facing).  Ensure that surface and ground water flows away from the site (i.e. build on upland areas).  If not, drainage pipes below the frost line may be required to prevent flooding. 
2. Your snake hibernaculum can be sized to fit the available space, but it must be deeper than the frost line (at least 2 meters deep).  Snakes prefer an overwintering site that is close to the water table, but not flooded.  Moist air ensures that snakes do not dehydrate over the dry winter months. 
3. Place rubble in the bottom to create chambers for the snakes.  Chambers created at different depths allow the snakes to move vertically and horizontally to select a preferred temperature/humidity microhabitat.
4. Concrete blocks or PVC drain pipes (with holes cut into the sides along the length of the pipe) can be used for entrances and passages to allow the snakes multi-level access.  Snakes use these passage ways to move to the bottom of the pit and into the underground chambers.  It is necessary to hand place the concrete blocks to ensure that a space or tunnel extends down into the bottom of the pit at each of the corners.  Continue to fill the pit with larger rocks, old concrete blocks and slabs, maintaining as many openings and chambers as possible. 
5. Cap with an insulating layer of smaller rock rubble.  Be sure to leave the entrances open and keep the top clear of shrubs that may grow as the site matures.
6. Protect emerging snakes from predators by having cover objects such as logs, rock piles, brush and uncut grass nearby. 
7. In the spring (mid April to late May), monitor your site to determine if wildlife are using the hibernaculum. Don’t get discouraged, it may take several years before snakes “discover” your hibernaculum.

Wild About Gardening has more information about building hibernaculums for toads and how to keep frogs in your pond as well.

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