Geographic patterns in population trends of neotropical migrants in North America

Abstract

We use the route-regression method to estimate the population trends of 100 species of Neotropical migrants using data from the North American Breeding Bird Survey (BBS). We examine long-term (1966-1988) and recent (1978-1988) trends. In the long-term, more species of Neotropical migrants were increasing than were decreasing in the eastern and western parts of the continent, but recent trends indicate that more species decreased than increased in their population index in the east. Recent population declines in the eastern part of the continent were primarily associated with bird species that breed in forested habitat. No association was detected between changes in forest acreages by state and population trends of Neotropical migrants in the United States and Canada.