Tree species, state of decay, and orientation in relation to woodpecker cavity nesting

Abstract

Many bird species construct nests to protect and incubate their eggs. Woodpeckers construct their nests in tree cavities they excavate themselves, and therefore can control what type of tree they are nesting in and where the entrance is oriented. Unhealthy trees of softer wood may be easier to excavate than healthy hardwood, and sunlight may assist parents in keeping their young at a stable incubation temperature. Based on historical accounts at the University of Michigan Biblogical Station and current observations, we hypothesized that woodpeckers favor dead or dying aspen trees, and their morning activity indicates that eastward facing holes would be the most favorable for sun exposure. We searched several northern Michigan forests for woodpecker nesting cavities and recorded the tree's state of decay and direction. Through our observations we determined that woodpeckers favor dead aspen trees, but there was no discernable preference for cavity direction. This data can inform future studies about the reproductive behavior of northern Michigan woodpeckers.