hibernation question...how smart are snakes?

[snakesarentevil]

I piled up a bunch of random length dimensional lumber behind my garage, partly with the idea of attracting snakes. It worked, as all summer under the right conditions I have had a variety of snakes basking, mostly fox, garter and brown snakes. Here in the Midwest, it gets very cold and the frost goes several feet deep (5 feet on a really cold year). The wood pile is on concrete, and as the temps get cooler I imagine that concrete will remain warmer temporarily. But as I understand it, snakes must find a place to hibernate which remains above freezing all winter.

My question: are the snakes smart enough to sense that hiding within/under this wood pile is not a good long term plan or will they be lured into a false sense of security and then die from freezing?

Thanks in advance