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 over 4,000 m in the Altiplano of Peru, Ecuador, and Chile. Severe eggshell thinning and pesticide contamination in eastern Mexico led to listing of the northern subspecies (Falco femoralis septentrionalis; Todd 1916a) as a U.S. Endangered species in 1986 (Kiff et al. 1980; Keddy-Hector 1986, 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 falcon displays great speed, agility and persistence in aerial pursuits of doves and other medium-sized birds. Mated pairs remain together year-round and hunt cooperatively. Diet is mostly birds and insects, but includes small mammals and reptiles; the species also kleptoparasitizes other birds. The Aplomado Falcon nests in abandoned platform nests of corvids and raptors, in bromeliads (Bromeliaceae), and sometimes on cliffs.
Prior to 1940, naturalist accounts and specimen records documented nesting activity in southeastern Arizona, south-central New Mexico, western Texas, and the lower Texas coast. Recent records (1990–present) have increased in southern New Mexico. Releases of captive-bred young are responsible for establishment of a small population in southern Texas, but attempts at restoration have been unsuccessful in New Mexico and West Texas. In Mexico, this species occurs in Aguascalientes, Campeche, Chiapas, Chihuahua, Guerrero, Oaxaca, San Luis Potosí, Tabasco, Tamaulipas, Veracruz, and probably other states, but it is most abundant along the Gulf coast in tropical lowlands of Campeche, Chiapas, Tabasco, and Veracruz. The desert grassland-dwelling population in Chihuahua and perhaps elsewhere in the central plateau of Mexico is imperiled by drought and habitat loss. Population declines have never been documented for any other part of Mexico, but determination of past and current status and trends have been handicapped by inadequate survey effort and corrupted locality data.
Loss or degradation of coastal grasslands, desert grasslands, marshlands and savannas to farmland, overgrazing, and improved pasture has eliminated much habitat for this species. Such habitat loss has likely been offset by conversion of tropical rain forest, deciduous forest, and thorn scrub to pasture. Loss of desert grassland habitat to irrigation and dryland farming is accelerating in central and northern Mexico. Introduction of exotic grasses as well as conversion of pasture to croplands and biofuel crops has likely degraded or eliminated habitat in all parts of the species’ range. Residues of organochlorine pesticides may now be too low to have much impact on eggshell thickness, although risk remains from endocrine disrupters, carbamates, organophosphates, and fire retardants near agricultural and industrial centers. Because the Aplomado Falcon often feeds on doves and quail, they are also vulnerable to ingestion of imbedded lead shotgun pellets. Widespread establishment of windfarms, as well as intensive oil and gas development and extraction activities are detrimental to this species. Restoration and protection of desert grasslands, coastal prairies, and tropical savanna and pasturelands are most critical to the long-term survival of this species in North America.