In doing some research for an upgrade to the home made cat
door I stumbled upon this fascinating project by Quantumpicture.com.
This home made cat door uses a low budget and clever way of taking a
picture just before the cat reaches the door to enter. If the picture
shows anything in your cats mouth like a mouse the computer tells the
door not to let him in. Same thing is true if a skunk or other animal
tries to get in. If he's all by himself the computer grants permission
and unlocks the door. You can also use this system to keep track of how
many times your cat goes in and out, complete with a fancy program that
will send a picture to your cell phone every time an event happens.
Our cats have always kept their hunting prizes outside, and Lucy does a
great job of keeping other small animals out of the yard, so we won't
be going to this extreme. Quantumpictures is working on a self
contained unit that will be available from their website in the near
future.