Almost half of all north american bird species are cavity nesters. 85 north american bird species such as ducks, owls, woodpeckers, bluebirds, and more find refuge in tree cavities. The cavities are used for habitat and food storage. Cavity nests are found in many different tree species like oaks, pines, aspens, and cottonwoods. Cavity nesters that create their own nest holes in trees are called primary cavity nesters (such as woodpeckers and flickers). Primary cavity nesters can excavate their nests in snags (dead standing trees) or harder live trees. Larger birds are able to excavate live trees. Cavity nests made in live trees tend to be more thermally regulated than in dead trees. Secondary cavity nesters (like owls and wood ducks) use existing holes created by primary cavity nesters or find space in already decaying snags. Non-bird animals like squirrels, bats, and bees may occupy cavities constructed by primary nesters.   

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Deforestation has occurred in New York ever since people began farming and changing their environment. Infrastructure, agriculture fields, pastures, and broader human impacts contribute to deforestation and habitat fragmentation. When trees are thinned less snags, old growth stands (large and undisturbed trees), and living trees are available for species to use. Habitat loss has lead some cavity nesters to become endangered. American kestrels, Eastern bluebirds, and wood ducks are secondary cavity nesters that have experienced large rates of habitat loss across New York state.