It’s hard to believe, but trees can actually provide more habitat for wildlife dead than when they are alive. Standing dead and dying trees, called “snags” or “wildlife trees,” are important for wildlife. Birds, small mammals, and other wildlife use snags for nests, nurseries, storage areas, foraging, roosting, and perching. Live trees with snag-like features, such as hollow trunks, excavated cavities, and dead branches can provide similar wildlife value. 
Snags often lack branches and dense canopies which allow for unobstructed flight movements by birds during predation. This makes snags optimal habitat for woodpeckers such as the Pileated Woodpecker which creates the majority of cavities used by secondary cavity users in forest ecosystems. 
In winter, northern flickers and other common backyard wildlife depend heavily on insects and other foods found in snags. Hollow snags are very valuable in winter as they are used by many species such as squirrels, raccoons, and owls, for dens and roosting. 
Large snags more than 12 inches in diameter and 15 feet tall offer ideal hunting perches for hawks, eagles, and owls. They function as resting perches for swallows, band-tailed pigeons, mourning doves and other birds; food storage areas for mice, squirrels, woodpeckers, and jays; and song perches for tanagers and flycatchers. 
Woodpeckers use large dead tree trunks as a way to announce their presence during courtship, hammering their bills against the tree’s resonating surface. Small snags may be used as song posts by bluebirds, hummingbirds, and other songbirds to attract mates and proclaim nesting territories. 
Have a dead tree and need to have it removed? Consider leaving the trunk and any limbs that are not dangerous. It will cost less and provide habitat for a while. Eventually it should be removed entirely if it is likely to fall on something, but in the meantime you’ll provide an important resource for wildlife.