|Dark green: All-year resident (contra this map, also in a large part of western Amazonia and interior of eastern Brazil)
Green: Breeding only
Beige: Area of breeding and vagrancy
The snail kite (Rostrhamus sociabilis) is a bird of prey within the family Accipitridae, which also includes the eagles, hawks, and Old World vultures. Its relative, the slender-billed kite, is now again placed in Helicolestes, making the genus Rostrhamus monotypic. Usually placed in the milvine kites, the validity of that group is under investigation.
Snail kites are 36 to 48 cm (14 to 19 in) long with a 99–120 cm (39–47 in) wingspan. They weigh from 300 to 570 grams (11 to 20 oz). There is very limited sexual dimorphism, with the female averaging only 3% larger than the male. They have long, broad, and rounded wings, which measure 29–33 cm (11–13 in) each. Its tail is long, at 16–21 cm (6.3–8.3 in), with a white rump and undertail coverts. The dark, deeply hooked beak, measuring 2.9–4 cm (1.1–1.6 in) is an adaptation to its diet. The tarsus is relatively long as well, measuring 3.6–5.7 cm (1.4–2.2 in).
The adult male has dark blue-gray plumage with darker flight feathers. The legs and cere are red. The adult female has dark brown upperparts and heavily streaked pale underparts. She has a whitish face with darker areas behind and above the eye. The legs and cere are yellow or orange. The immature is similar to adult female, but the crown is streaked.
Distribution and ecology
The snail kite breeds in tropical South America, the Caribbean, and central and southern Florida in the United States. It is resident all-year in most of its range, but the southernmost population migrates north in winter and the Caribbean birds disperse widely outside the breeding season.
The snail kite is a locally endangered species in the Florida Everglades, with a population of less than 400 breeding pairs. Research has demonstrated  that water-level control in the Everglades is depleting the population of apple snails. However, this species is not generally threatened over its extensive range.
In fact, it might be locally increasing in numbers, such as in Central America. In El Salvador, it was first recorded in 1996. Since then, it has been regularly sighted, including immature birds, suggesting a resident breeding population might already exist in that country. On the other hand, most records are outside the breeding season, more indicative of post-breeding dispersal. In El Salvador, the species can be observed during the winter months at Embalse Cerrón Grande, Laguna El Jocotal, and especially Lago de Güija. Pomacea flagellata apple snails were propagated in El Salvador between 1982 and 1986 as food for fish stocks, and it seems that the widespread presence of high numbers of these snails has not gone unnoticed by the snail kite.
Snail kites have been observed eating other prey items in Florida, including crayfish in the genus Procambarus and black crappie. It is believed that snail kites turn to these alternatives only when apple snails become scarce, such as during drought, but further study is needed. On 14 May 2007, a birdwatcher photographed a snail kite feeding at a red swamp crayfish farm in Clarendon County, South Carolina.
- BirdLife International (2012). "Rostrhamus sociabilis". IUCN Red List of Threatened Species. Version 2013.2. International Union for Conservation of Nature. Retrieved 26 November 2013.
- J. Ferguson-Lees,David A. Christie (2001) Raptors of the world: SNAIL KITE (Google Books). ISBN 978-0618127627
- Raptors of the World by Ferguson-Lees, Christie, Franklin, Mead & Burton. Houghton Mifflin (2001), ISBN 0-618-12762-3
- "Lake Okeechobee Low Lake Stage Restoration Projects".
- Herrera et al. (2006)
- Davis, Steven M.; John C. Ogden (1994). Everglades: The Ecosystem and its Restoration. CRC Press. p. 508. ISBN 978-0-9634030-2-5.
- Pogatchnik, Shawn (2007-06-12). "Bird watcher spots snail kite in S.C.". News Room Media. Associated Press. Retrieved 2009-07-30.
- "Everglade Snail Kite discovered near Rimini, SC". Cape Romain Bird Observatory. Retrieved 2009-07-30.
|Wikimedia Commons has media related to Rostrhamus sociabilis.|
- Herrera, Néstor; Rivera, Roberto; Ibarra Portillo, Ricardo & Rodríguez, Wilfredo (2006): Nuevos registros para la avifauna de El Salvador. ["New records for the avifauna of El Salvador"]. Boletín de la Sociedad Antioqueña de Ornitología 16(2): 1-19. [Spanish with English abstract] PDF fulltext
- Snail Kite Information Great Florida Birding Trail