The Effect of Gypsy Moth Defoliation on Cavity-Nesting Bird Communities

Abstract

Abstract Gypsy moths (Lymantria Dispar) kill trees and create snags, a resource vital to cavitynesting birds. With this in mind, population trends of 11 cavity-nesting birds and their relationship to snags in an area that was defoliated by gypsy moths were investigated from 1984 to 1999. Vegetation and bird point-count data from before a major gypsy moth outbreak (1984–1986), during (1987–1988), and after (1989–1999) enabled us to ake inferences about this forest bird community. The combined abundance of the 11 cavity-nesting species examined increased during the years immediately after the outbreak (1989–1993) followed by a decline in the last 6 yr (1994–1999). The abundance of snags also increased from 1989 to 1993 followed by a decline from 1994 to 1999. Regression analysis confirmed that cavity-nesting bird populations were highly associated with snag abundance. These data suggest the importance of snags to cavity-nesting birds and that cavity-nesters were able to take immediate advantage of a new population of snags. FOR. SCI. 48(2):273–281.