The influence of disturbance events on pileated woodpeckers in Northeastern Oregon

Abstract

The pileated woodpecker ( Dryocopus pileatus) is a species of conservation concern and an indicator of mature and old forest habitat conditions in the Pacific Northwest. The effects of natural and human-caused disturbance on density of nesting pairs, reproductive success, and traditional home ranges were compared over 30 years in two areas and over 15 years in five additional areas. In one study area, density of nesting pairs of pileated woodpeckers decreased from five to one after extensive regeneration cuts eliminated most of the stands of mature and old-growth grand fir ( Abies grandis) and reduced the density of nest and roost trees and foraging substrate since 1990. Density of nesting pairs, reproductive success, and home range location remained fairly consistent over 30 years in a second study area with extensive tree mortality resulting from insect outbreaks but without regeneration harvests. The amount of unharvested stands and closed canopy stands in home ranges were positively correlated with reproductive success, and the amount of area in harvested stands was negatively correlated with reproductive success in 2003–05. High tree mortality and subsequent loss of canopy closure in stands of grand fir and Douglas-fir from insect outbreaks did not appear to be detrimental to pileated woodpeckers provided that dead trees and logs were abundant and that stands were not harvested.