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Snail Kite
Rostrhamus sociabilis

Status: Lower risk

Population Trend: Declining.

Other Names: Cuban Snail Kite (levis), Everglade Kite (plumbeus), Everglade Snail Kite (plumbeus), Mexican Snail Kite (major), South American Snail Kite (sociabilis).

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Rostrhamus sociabilis
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Distribution: Nearctic/Neotropical. UNITED STATES (Florida), CUBA (including Isle of Pines), and MEXICO (Guerrero, Veracruz, Yucatan Peninsula) south locally through Middle America west of the Andes to ECUADOR and east of the Andes through COLOMBIA, VENEZUELA, and the Guianas south to central ARGENTINA, southern BRAZIL, and URUGUAY; absent from much of northern Amazonia. more....

Subspecies: 3 races. R. s. plumbeus: UNITED STATES (Florida), CUBA, and Isle of Pines; R. s. major: Eastern MEXICO (Veracruz), BELIZE, GUATEMALA, and probably EL SALVADOR; R. s. sociabilis: HONDURAS and NICARAGUA south through PANAMA to South America west of the Andes in COLOMBIA and ECUADOR and east of the Andes south to URUGUAY and central ARGENTINA, except for higher areas (Guyana Massif, Brazilian Plateau) and much of northern Amazonia. more....

Taxonomy: The study of Lerner and Mindell (2005), based on molecular sequences from two mitochondrial genes and one nuclear intron, showed that this genus is more closely related to the buteonine taxa than to other kites and that is does not fall into any of the three kite clades, Elaninae, Perninae, or Milvinae, and the molecular study of Griffiths et al. (2007) also supported this conclusion. Further molecular studies by Lerner et al. (2008) suggested that Rostrhamus is sister to Geranospiza, but with low support. More recently, Amaral et al. (2009) showed that this monotypic genus belongs to a clade also containing Rostrhamus sociabilis and Busarellus nigricollis, based on more detailed studies of the sequences of both mitochondrial and nuclear genes. This clade is a sister group to the other buteonines, except for Ictinia< and Butastur. more....

Movements: Partial migrant (Bildstein 2006). Undergoes frequent local movements in response to changing water conditions. Categorized as an "austral partial migrant" by Chesser (2004), Stotz et al. (1996), and Bildstein (2004). Sick (1993) mentioned a flock of about 1,000 birds seen in Sapucaia do Sul, Rio Grande do Sul in October. The disjunct Florida population does not migrate south in the winter, but is nomadic at times. Olivo (2007) recorded apparent migratory activity at La Concepción in the lowlands of eastern Bolivia, where there was a migratory peak in the first week of November. Ortiz and Capllonch (2007) reported that birds breeding in central Argentina migrate northward in the non-breeding season to northern Argentina and probably the Brazilian Pantanal. more....

Habitat and Habits: Occurs in lowland freshwater marshes, lakes, ponds, sloughs, rice fields, flooded fields, and roadside ditches. Perches on low posts, bushes, or even on ground, and returns to favorite perches. Roosts in large flocks in central places, traveling in large flocks to the roosts at dusk, and even forages in loose groups, but, as pointed out by Slud (1964), "it is colonial in the sense that environmental exigencies restrict it to particular sites." This species is particularly adept at locating new or temporarily available patches of wet habitat. more....

Food and Feeding Behavior: Specialist on freshwater snails, mostly of the genera Pomacea and Ampullaria, which are extracted from their shells with the strongly hooked bill; the shells are discarded undamaged under feeding perches (Murphy 1955, Sick 1993). Also recorded feeding on crabs in Venezuela, Brazil, and Argentina, and on a turtle in Florida. Foraging birds fly low over marshlands, descending to pluck snails from just under the water or from vegetation with their feet, then returning to a favorite perch to feed. more....

Breeding: Builds a flimsy, unlined stick nest placed in low tree or bush over water, and several pairs often nest in close association.  Clutch size is 1-4 eggs (usually 2 or 3), which are buffy-white and heavily marked with brown splotches. more....

Conservation: Conservation Dependent in Florida and Central America, but Lower Risk in South America. One of the most abundant raptor species in suitable wetland habitat in southern South America, but there have been population declines in other areas, including Ecuador (Ridgely and Greenfield 2001), and Brazil (Sick 1993), due to the draining of marshes and wetlands. However, Snail Kites have recently colonized new breeding sites in other countries, including El Salvador (Jones and Komar 2009), Costa Rica (Jones and Komar 2007), and Panama (Angehr 1999). The disjunct Florida population has always had peculiar conservation problems, relating mostly to both natural and human-induced variations in water conditions, and there is an ongoing controversy over the importance of these effects. It hit a low of only 65 birds in 1975 (Goodrich 2006), but rebounded to a high of 3,577 birds by 1999 (Martin 2007). Since then, the population has declined dramatically and is predicted to continue to decline (Martin 2007). Categorized as a species of Least Concern by BirdLife International (2009) at the species level. more....

Population Estimates: The Florida population was recently estimated at approximately 1,600 birds (Martin et al. 2007).

Important References: 
Beissinger, S.R. 1988. The Snail Kite. Pp. 148-165 in R.S. Palmer (ed.),
  Handbook of North American birds. Vol. 4. Diurnal raptors. Pt. 1. Yale
  University Press, New Haven, CT.
Bent, A.C. 1937. Life histories of North American birds of prey. Order
  Falconiformes (Part 1). U.S. National Museum Bulletin 167.
Bierregaard, R.O. 1994. Snail Kite. Pp. 116-117 in del Hoyo, J., A.
  Elliott, and J. Sargatal (eds). Handbook of birds of the world. Vol. 2. New
  World vultures to guineafowl. Lynx Edicions, Barcelona, Spain.
Ferguson-Lees, J., and D.A. Christie. 2001. Raptors of the world. Houghton
  Mifflin, Boston, MA.
Sykes, P.E., Jr. 1984. The range of the Snail Kite and its history in
  Florida. Bulletin of the Florida State Museum, Biological Sciences
  29:211-264.
Sykes, P.W., Jr., and J.A. Rodgers, Jr., and R.E. Bennetts. 1995. Snail
  Kite Rostrhamus sociabilis. In A. Poole and F. Gill (eds.), The Birds of
  North America no. 171. Academy of Natural Sciences, Philadelphia, and
  American Ornithologists' Union, Washington, D.C.
more....

Sites of Interest:
Xeno-canto
Vocalizations.
VIREO
Snail Kite photos.
Aves de Rapina do Brasil
Species account, with emphasis on Brazil.

Researchers:
Gallardo Del Angel, Julio Cesar
Leveau, Lucas
Mealey, Brian
Nurinsiyah, Ayu Savitri
Olivo Quiroga, Cristian E.
Rodríguez Santana, Freddy

Last modified: 11/7/2010

Recommended Citation: Global Raptor Information Network. 2014. Species account: Snail Kite Rostrhamus sociabilis. Downloaded from http://www.globalraptors.org on 20 Apr. 2014








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