Birds in trees leave signs of their presence, such as nests, droppings, and tree damage. Individuals may notice nests in hollow cavities, woven between branches, on the sides of trunks, or even suspended from branches. Though their appearance and size varies from species to species, bird nests are typically constructed of twigs, leaves, and strands of fiber. The presence of droppings on trunks, branches, and the ground underneath trees also indicates the existence active infestations. Other signs of birds in trees include holes pecked into trunks, broken branches, and nibbled fruits and nuts.