Another type, uses the weight of the squirrel to close the door to the bird feeder, and once the squirrel leaves, the port opens and the birds can once again access the food.
There are other type of squirrel proof feeders that use a baffle to keep squirrels from the food. This is where large domes or tubes are constructed on the birdhouse, and squirrels can not jump over it or climb around.
Another type are caged feeders that keep out the small rodents by surround the feeder with a wire cage. There are openings in the cage which are the perfect size for birds to feed from, but not wide enough for squirrels.
To read more Attracting Birds With Squirrel Proof Feeders
