Save that Snag!
Dead trees are known as “snags.” Living trees with dead and dying limbs are called “decadent.” Red-headed Woodpecker Recovery encourages the use of the term “wildlife tree” to describe dead and decadent trees. These trees are essential to Red-headed Woodpeckers, and are valuable for other wildlife as well as for overall forest health.
Red-headed Woodpecker Recovery has produced a document highlighting the value of wildlife trees.
The US Forest Service also has a good web site regarding wildlife tree preservation: Animal Inn: There’s life in dead trees.