There are a lot of motion sensor cameras out there. They can be set to either still or video. When motion is detected, off they go. The ones I'm familiar with have a relatively short range (10 to 20 feet).
The trick is securing them. Ideally, you cable them to something solid, like a tree, so they can't be stolen. They can also be smashed or otherwise vandalized. I have a couple of friends who use motion sensor cameras to photo wildlife. I can find out more info pretty easily.
Like I say, though, the trick is to find a good place to mount the camera where it will be secure, unlikely to be detected, and have a good view of the boxes.
HJ
