Squirrels
Squirrels may also help themselves to the contents of bird feeders, often not merely feeding, but carrying away the food to their hoard. There are various anti-squirrel techniques and devices available to thwart attempts by squirrels to raid bird feeders. Several manufacturers produce feeders with perches that collapse under the weight of anything heavier than a bird, or that use battery power to shock an intruder lightly or spin the perching area to fling it off. Caged feeders are often designed so that squirrels cannot reach the seed inside, but birds can easily fly through the cage's holes. Caged feeders are best to keep out gray squirrels. Chipmunks and red squirrels can usually enter caged feeders. Hot pepper in bird seed and suet has also been shown to be effective against squirrels without harming birds, according to a 1999 Cornell study by Curtis, Rowland & Dunn. Mammals, not birds, appear to be bothered by capsaicin oleoresin.
The placement of a bird feeder can also prevent squirrels from accessing the seed. In addition, baffles can be used that prevent squirrels from gaining their footing above feeders. Below feeders, baffles can prevent squirrels from climbing any further, however squirrels are very agile and acrobatic and often find a way to overcome devices of any nature.
Read more about this topic: Bird Feeder