Although some feeders are squirrel-proof, not all resist other large mammals. Depending on which kinds of animals live around your area, you may need to take extra precautions. Some mammals, including squirrels, are sensitive to spices, but birds are not. You may consider adding cayenne pepper or other spices to your seeds to help keep them away. If you have bears in your area, place your feeder on a sturdy metal pole at least 10 to 12 feet high to keep them away.