One of the largest wildlife guilds on the refuge consist of members that either excavate their own cavities in a snag or dead top or utilize natural cavities and those excavated by others. There are twenty-nine species in this guild including the red-napped sapsucker, northern flicker, western bluebird, and the big brown bat. Optimum conditions for cavity nesting birds require on the average 3 suitable snags per acre greater than 15 inches (38 centimeters) in diameter.
Currently the average density of snags in refuge forest stands is less than 1 per acre. Past logging and suppression of fire has resulted in the loss of mature and old growth stands that produce large diameter snags that persist over long periods of time. Current forest restoration activities will increase the number of trees in the larger size classes and reintroduction of fire will recruit additional snags.