The Aplomado Falcon is a colorful, long tailed, long-legged falcon that inhabits lowland Neotropical savannas, coastal prairies, and higher-elevation grasslands from the southwestern United States south to Tierra del Fuego. It ranges from sea level to at least 4,000 m in the Altiplano of Peru and Ecuador. Severe eggshell thinning and pesticide contamination in eastern Mexico led to listing of the northern subspecies (Falco femoralis septentrionalis Todd 1916a ) as a federally Endangered species in 1986 ( Kiff et al. 1980 ; Keddy-Hector Keddy-Hector 1988 , Keddy-Hector 1990 ).
Proportioned and behaving somewhat like an accipiter hawk, with a tendency to perch on inner branches of trees and chase terrestrial prey on foot, this bird displays great speed in long aerial pursuits of doves and pigeons. Mated pairs remain together year-round and hunt cooperatively. Its diet is mostly birds and insects, but also small mammals and reptiles, and it kleptoparasitizes other birds. Aplomados nest in bromeliads (Bromeliaceae) or abandoned stick platforms of corvids and other raptors.
This species currently occurs in Campeche, Chihuahua, Oaxaca, San Luis Potosí, Tabasco, Tamaulipas, Veracruz, and probably other Mexican states. Determination of past and current status and trends in the United States is complicated by inconsistent sampling efforts and ongoing, rapid establishment of captive-reared individuals in Texas and northern Mexico. Reliable specimen records document past nesting activity at 6 general localities in southeastern Arizona, south-central New Mexico, western Texas, and the lower Texas coast. Scattered sightings over the past 50 years suggest continued ephemeral occupancy of the United States and northward dispersal from Mexico.
Loss or degradation of coastal grasslands, desert grasslands, and marshlands and savannas to farmland, overgrazing, and improved pasture has eliminated much native grassland habitat for this species, while also increasing exposure to pesticides. Such habitat loss has been, at least partially, offset by conversion of tropical rain forest, deciduous forest, and thorn scrub to pasture. Evidence of continued contamination of potential falcon prey by organochlorine pesticides, mercury, selenium, and lead, plus heightened risks of organophosphate poisoning, favors intensified efforts to eliminate such environmental contamination from United States and Mexican ecosystems. This, coupled with restoration of desert and coastal grassland and tropical savanna, must become top priorities for long-term conservation of this species.