The potential for comparative research across New World bird migration systems

Abstract

For a migratory bird, the costs and benefits of utilizing a given migratory strategy vary according to the biotic (e. g., physiology) and abiotic (e. g., weather) constraints it experiences throughout the year. In the New World, closely related species migrate to breeding grounds located across a wide range of latitudes, from northern North America to southern South America. Because the ultimate goal of a bird on spring migration is to successfully arrive on the breeding grounds in a timely manner, events that occur during the breeding season (e. g., amount of time available to breed) could affect, through selection pressures, the behavior of birds on spring migration. Variation across north temperate, tropical, and south temperate latitudes in breeding strategies, breeding season length, and availability of food during the breeding season has been well documented in various bird species. Thus, such factors as migratory strategies, risk of mortality on migration, and effects of climate change on migratory patterns may also vary predictably, depending on the latitude, both north and south of the Equator, at which a migratory population breeds. Comparing such patterns across the New World, using interdisciplinary approaches and the latest in technological advances, holds promise for better understanding how migratory birds accomplish these spectacular journeys.