ABSTRACT
Abstract. Climate change has increased worldwide temperatures, affected seasonal patterns, and altered important sources of natural selection. To manage wildlife populations successfully, we must understand how patterns and processes of climate change alter trade-offs between sources of selection to predict how individuals may respond, populations may evolve, and management actions may ameliorate the costs of changing climates. Here we discuss how the migratory patterns of leapfrog and chain migration facilitate or constrain responses by migratory songbirds to spatial and temporal variation in climate change across western North America. Based on 52 years of climate data, we show that changes in average minimum monthly temperature differ significantly
between the spring migration zone in the desert Southwest and breeding locations throughout western North America, and that these differences are most extreme for populations breeding at low latitudes (37°–49°) and exacerbated for species exhibiting leapfrog migration. Given the importance of climate in the evolution of migratory behaviors, such extreme alterations in the geographical patterns of climate may ultimately threaten the long-term population viability of species dependent on low latitudes for breeding or exhibiting leapfrog migration.
