Characteristics and dynamics of cavity nest trees in southern British Columbia

Abstract

We report on the characteristics, persistence, and temporal use patterns of nest trees of cavitynesting wildlife in coniferous forests of southern British Columbia, Canada. Our goal is to identify the types of trees required to be retained during forestry operations if viable populations of cavity nesters are to be maintained in managed forests. Between 1994 and 1999, we recorded nesting species and tree characteristics during the year of first detection of active nest trees and in subsequent years, to document changes in wildlife use and tree condition. We located a total of 602 nests of 16 cavity-nesting species in 420 trees. Predominant tree species with active nests were Douglas-fir (Pseudotsuga menziesii), western larch (Larix occidentalis), trembling aspen (Populus tremuloides), and paper birch (Betula papyrifera). More than half of all nest trees were dead and/or partially broken when first detected. Three to 4.5 percent of nest trees were lost due to uprooting or total breakage each year. Partial breakage occurred at average annual rates of 1.1 to 6.2 percent each year. During the study period, 30 percent of nest trees were reused by breeding cavity nesters.