Most use a spring loaded or counter weighted gate that closes off access to the seed ports under the squirrel's weight. This weight adjustment can be altered to selectively exclude larger, non-target birds as well. Some bird watchers have been using seeds that are coated with hot pepper or capsaicin products. Theoretically, squirrels avoid the coated seed while birds are unaffected. Researchers at Cornell University continue to test this theory.
Cats Cats are the most numerous pet in North America.
Unfortunately, they kill hundreds of millions of birds each year. Feeder birds are also easy prey. If you own a cat, we strongly recommend that you keep it indoors to reduce this needless loss. Campaign to increase awareness of the problem. If bears, raccoons, deer, or moose become a nuisance the best tactic is to make your feeders inaccessible with fencing.