Many migrating raptors follow distinct routes during autumn and spring migrations.
Topography and water barriers largely define these routes, which vary among species and …

We assessed the conservation status of 20 species of North American birds of prey by
examining historical and recent estimates of trends in counts of raptors at migration …

We analyzed counts from 10 watchsites in western North America. Average counts at
watchsites ranged from 2,000 to 15,000 migrants each autumn, with as many as 21 species …

La distribución global de los colibríes (familia Trochilidae, orden Apodiformes) se restringe
al continente americano (Johnsgard 1997). Se creía que el grupo había evolucio nado …

Natural variation in migratory strategies across the range of the American Kestrel (Falco
sparverius) creates a unique opportunity for comparative research of annual cycles …

Recent conservation plans for long-distance Neotropical migrant birds have emphasized the
importance of understanding the ecology and threats facing a species throughout its life …

Continental-scale bird population estimates are used as a decision-support tool in
conservation plans. The calculation of these estimates includes the use of density values …

We estimated trends in autumn counts of migrating diurnal raptors collected at four
watchsites around the Gulf of Mexico: Florida Keys Raptor Migration Project at Curry …

Los censos durante la migración han sido utilizados como una herramienta válida para
determinar estatus poblacionales de aves rapaces. En Veracruz, México, éstos tienen la …

Climatic factors influence migration behavior in both short-and long-distance migratory birds.
The Broad-winged Hawk (Buteo platypterus) is a long-distance migrant that exhibits a …