Migratory Distance Relationship to Population Decline in Aerial Insectivores

While migration provides optimal seasonal conditions for feeding and breeding, migratory birds face many life-threatening obstacles throughout each journey. Such obstacles may include the high energetic demands accompanying flight and feeding practices, as well as increased mortality associated with environmental pressures such as predation and transmission of intraspecies disease. Species travelling farther distances are likely to pay higher energy costs and endure greater environmental pressure. In North America, the populations of long-distance migratory birds that rely on insect niches have noticeably fallen. Aerial insectivore populations are disproportionately declining when compared to other migratory guilds. This study aims to determine whether migration distance may be used to predict population decline, and to examine the relationship between migratory distance and aerial insectivore population decline relative to occupants of other migratory guilds. The distances between centroids of the breeding ranges and non-breeding ranges of North American birds will be compiled using automated GIS analysis of species distribution maps