ORIGINAL: Bigg~BirddVA
Just get the cheapest digital trail cam you can that has a date/time stamp. Forget the pics and count blank exposures. If you do get something then it's just a bonus over what you wanted. As far as I know there is nothing like what you're looking for.
Thats probably the best idea. Here is something like what you want
http://www.trailtimer.com/5event-tt500.htm
but at $135... might as well get a cheap digi and put a big sd card in it.