Potential Effects of Climatic Change on a Neotropical Migrant Landbird

ABSTRACT

Abstract:Significant climatic changes due to the "greenhouse" effect are predicted to occur in breeding and Wintering areas of neotropical migrant landbirds within 50 years. A simulation model was used to quantitatively evaluate the impact of predicted climatic changes on the annual productivity (number of fledgling · pair⁻¹ season⁻¹) of Blackthroated Blue Warbllers (Dendroica caerulescens). breeding in northern hardwoods forests. Results suggested that where mean summer rainfall increases by 20%, greater egg and nestling mortality may reduce annual breeding productivity by as much as 26%. Warmer temperatures however, will tend to enhance food abundance for insectivorous birds and lengthen the avian breeding season. These changes will act to increase breeding productivity, but they can only compensate for about a 10% increase in precipitation. Precipitation, however, is predicted to decline over most of the range of Black-throated Blue Warblers. Where mean temperature is warmer and average summer precipitation is lower by as little as 10%, breeding productivity of Black-throated Blue Warblers may be enhanced by up to 25%. Because significant regional differences in climatic change are likely, and because migratory bird species will differ in their response to climatic change, the emphasis of avian research should be on intensive regional studies of the factors influencing avian reproduction and survival.