During severe cold several chickadees sometimes share their body heat by roosting together in a single cavity. Save a Snag for Wildlife Dead trees, or snags, are valuable to a wide variety of wildlife. Unfortunately, many people assume snags are of no value and routinely cut them down. In some places, this practice has caused cavity-nesting bird and mammal populations to decline. Though nest boxes may provide alternate nesting sites for some cavity-nesting birds, they are not suitable replacements for dead trees.
Woodpeckers use snags for drumming, nesting, roosting, and feeding.
Snags provide ideal feeding sites for woodpeckers as many insects live and reproduce in decaying wood. Many snags are covered with small holes made by foraging woodpeckers. Though woodpeckers have powerful bills and neck muscles, they are only able to excavate nests in trees with soft decaying centers. Thus, dead or dying trees are preferred excavation sites. Unlike most other cavity-nesting birds, woodpeckers rarely use birdhouses.