Hikermor, you may want to try a UV flashlight as well. They are inexpensive and can help detect many different things that otherwise would be invisible to the naked eye. A very good one will run about $30.

I plan on going outside and looking at the house tonight (temps in the teens), and see if I can get my son to go hide in the bushes. I am not sure yet of the range of the FLIR, but will try it out.

Any ideas at all of how to test the capabilities wold be appreciated.