Falcons
Current Status Of North American Falcons
- Aplomado falcon (Falco femoralis). Endangered (sub)Species. Has been reintroduced in Texas. Decline in population is thought to have been due to agricultural expansion and to eggshell thinning resulting from the use of pesticides. Now considered a Southwestern stray.
- Collared forest falcon (Micrastur semitorquatus). Southwestern stray.
- Peregrine falcon (Falco peregrinus). Pesticides and PCB poisoning caused widespread reproductive failure from the 1940s to 1970s, causing species to disappear from many of the former nesting grounds. It has since been reintroduced in many areas, and appears to be doing well locally.
- Prairie falcon (Falco mexicanus). Species has experienced some eggshell thinning and mercury poisoning (mainly built up from feeding on the seed-eating Horned lark). Has declined in some areas (including Utah, western Canada, and agricultural regions of California), but the current population appears stable.
- American kestrel (Falco sparverius). Decline in population in the northeast in recent years, but otherwise the population appears stable. Nest boxes have helped maintain populations in some areas.
- Gyrfalcon (Falco rusticolus). Rare. Has declined in parts of Arctic Europe, but appears stable in North America. Illegal poaching for falconry may be a problem in some areas, but fortunately most nest sites are out of range of human disturbance.
- Merlin (Falco columbarius). There were earlier indications that this bird was experiencing adverse effects from the use of pesticides in eastern Canada, and from mercury buildup in western Canada. Numbers now appear to be increasing in the northern prairies, and to be remaining stale elsewhere.
- Crested caracara (Polyborus plancus). Has declined due to loss of habitat due to agricultural expansion and hunting. There has been some evidence of an increase in population in Texas. The population on Guadalupe Island, Mexico, became extinct in 1900.
Resources
Books
Cade, T.J. The Falcons of the World. Ithaca, NY: Cornell University Press, 1982.
Ehrlich, Paul R., David S. Dobkin, and Darryl Wheye. The Birder's Handbook. New York: Simon & Schuster Inc., 1988.
Freedman, B. Environmental Ecology. 2nd ed. San Diego: Academic Press, 1994.
Peterson, Roger Tory. North American Birds. Houghton Miflin Interactive (CD-ROM), Somerville, MA: Houghton Miflin, 1995.
Randall Frost
Additional topics
Science EncyclopediaScience & Philosophy: Evolution to FerrocyanideFalcons - Interaction Of Falcons With Humans, Current Status Of North American Falcons