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Status: Population size: Global population unknown U.S. population 1,000 Photo by Cornell Laboratory of Ornithology.

Snail Kite
(Rostrhamus sociabilis)

A signature species of the Everglades, the Snail Kite occurs in the U.S. only in south Florida where it is highly dependent on water levels to maintain the wetland habitats for its primary food source, the apple snail. A remarkable example of evolutionary adaptation, its curved beak is amazingly efficient at removing snails from their protective shells. The species can be found in freshwater areas throughout much of Central and South America. One subspecies, Rostrhamus sociabilis plumbeus is found only in Florida, and is Federally listed as Endangered.

Identification
The slender curved bill of this species sets it apart from most other raptors in its limited U.S. range. Adult males are slate gray, with reddish legs. Adult females also have reddish legs, but are mostly brown in color, with a streaked breast and belly. In flight, both sexes show a conspicuous patch of white at the base of the tail.

Distribution and Population Trends
Four sub-species have been described, all in the Americas. The U.S. subspecies Rostrhamus sociabilis plumbeus is a year-round resident of Florida. Snail Kites are found near freshwater lakes, marshes and waterways, where they can find their primary food source - snails. Distribution in the Florida subspecies is generally confined to the Kissimmee River valley, the Lake Okeechobee area, the St. John's River system and the Everglades.

Once widespread in the Florida peninsula, populations declined dramatically as wetland habitat was altered throughout the state. U.S. population in the 1940's was estimated at less than 100 individuals. Counts conducted since1969, however, show a generally increasing population trend. Elsewhere in the Americas, Snail Kites can be abundant, though local declines occur in areas where development and water management regimes have led to the loss of year-round wetlands.

Ecology
A highly specialized predator, Snail Kites feed almost exclusively on snails. In Florida the species relies on the availability of apple snails (Pomacea paludosa) which they pluck from under the water using only their talons. The U.S. population is non-migratory, though birds will move in response to food availability. Thus Snail Kites are sensitive to droughts and/or other changes that impact the hydrology of their foraging habitat.

Breeding takes place throughout much of the year (usually Dec - Jul). Nests are built over water to deter terrestrial predators. Loose aggregations are often formed with nesting of colonial waterbird species ( like egrets and Anhingas). When water levels change in nesting areas, kites may be forced to build nests away from the shoreline in less stable vegetation. Nests built on pliant grasses and reeds often lead to greater rates of nest failure. An average of 3 eggs are laid per clutch.

Threats
The main threat throughout its range is the loss of wetland habitat, though this problem is most critical in the U.S and possibly Cuba. The Florida population is extremely vulnerable because of its restricted range and relatively small population size. Alteration of the natural flow of water in this state continues to be a threat (although in some areas, water impoundment has had a positive impact on the species). Runoff water containing fertilizers can lead to eutrophication in foraging grounds which can promote the rapid growth of invasive plants (such as water hyacinth), further reducing available foraging habitat.

Conservation
The U.S. population is listed as an endangered species, and is protected by State and Federal law (see: http://ecos.fws.gov/servlet/SpeciesProfile?spcode=B00F). As such the species has benefited from active management under the Snail Kite Recovery Plan. Positive steps for the conservation of this species have included habitat protection and improvements in water management. In some areas, artificial nest structures have been used to increase nesting success (Roderick Chandler of Audubon pioneered these techniques. To read more about Rod Chandler see http://www.audubonofflorida.org/conservation/kp.htm ).

What Can You Do?
Fertilizers often find their way into Florida's river systems, and can lead to eutrophication and rapid growth of plants (like water hyacinth) that choke up small lakes and waterways. Many of these fertilizers find their way into the water systems from agricultural land, but homeowners are also contributing to the problem. To learn how you can reduce your use of fertilizers and pesticides around the home, visit our Audubon at Home program (see: http://www.audubon.org/bird/at_home/index.html) and download "Audubon's Guide to a Healthy Yard and Beyond" (Download PDF: http://www.audubon.org/bird/pdf/healthyyard.pdf).

Audubon is a leading member of the coalition working to restore the magnificent Everglades ecosystem. This monumental task will restore the natural water flow through many of the waterways important to the endangered U.S. population of Snail Kites as well as countless other species. . This work would not have been possible were it not for the efforts of interested individuals in Florida and elsewhere. Read more about this historic project and learn how you can help by visiting: http://www.audubonofflorida.org/science/everglades.htm

Audubon's Important Bird Area Program is working to identify and protect habitat that is critical to birds in North America and around the world. To learn more about the Important Bird Areas program in Florida visit: http://www.audubon.org/bird/iba/fl.html

References
Sykes, P.W., Rodgers, J.A. and Bennetts, R.E. 1995. Snail Kite (Rostrhamus sociabilis). In The Birds of North America, No. 171 (A. Poole and F. Gill, eds.). The Academy of Natural Sciences, Philadelphia, PA and The American Ornithologists' Union, Washington, D. C.

Ferguson-Lees, J. and Christie, D. A. 2001. Raptors of the World. Houghton Mifflin Company, New York.