- 29.5–37.4 in
- 42.9 in
- 46.7–47.6 oz
- Water-turkey, Snake-bird
- Anhinga d'Amérique (French)
- Anhinga americana, Pato aguja, Cotua agujita, Cotua real, Bigua vibora (Spanish)
- The Anhinga is frequently seen soaring high in the sky overhead. It is a graceful flier and can travel long distances without flapping its wings, much in the manner of a Turkey Vulture.
The Anhinga lives in shallow, slow-moving, sheltered waters and uses nearby perches and banks for drying and sunning. It's rarely found out of freshwater except during severe droughts. Generally not found in extensive areas of open water, though it may nest on edges of open bays and lakes. Breeds near freshwater, often in association with other waterbirds such as herons, egrets, ibises, storks, and cormorants. The Anhinga may also breed in saltwater colonies and feed in fresh water.
The Anhinga dives from the surface of the water and swims slowly underwater stalking fish around submerged vegetation. The diet consists of many small- to medium-sized wetland fishes, with very small amounts of crustaceans and invertebrates. Anhingas typically spear fish through their sides with a rapid thrust of their partially opened bill. Usually stabs with both mandibles, but may use upper mandible only on small fish. The side-spearing habit of the Anhinga suggests that the usual hunting method is by stalking rather than pursuit.
- Egg Description
- Conspicuously pointed at one end, pale bluish green, and overlaid with a chalky coating.
The male begins nest construction before it has a mate, by placing large sticks and green material in the forks of trees. The male collects nearly all nesting the material, and the female then finishes building nest. The nest is a bulky platform of sticks, somewhat more compact than heron nests. It is often lined with fresh leaves, green twigs, willow leaves, and catkins. With age, excrement can build up on the outer rim of the nest giving it a white appearance.
The Anhinga typically nests in loose groups of several to hundreds of pairs and sometimes with other colonial waterbirds. The nest is usually in a tree near to water or overhanging it.
The Anhinga swims lower in the water than many other birds due to its reduced buoyancy—a result of wetted plumage and dense bones. When at the surface, they tend to swim low in the water, often with only the neck and head above the water and sometimes with only the bill exposed. The Anhinga is also an adept soarer. While soaring, it holds its wings flat and straight, its neck outstretched or held with a slight kink; its long, straight tail is conspicuous. Anhingas often use thermals for soaring, and may achieve altitudes of several thousand feet.
Anhinga populations seem stable. They can be vulnerable to entanglement with discarded fishing line. Their aquatic lifestyle means they accumulate pesticides and other contaminants if those are in the water—people have even studied Anhingas as indicators, to determine whether the water they live in is contaminated. Typically, the pollution levels that have been measured in this way have been at levels below what is considered detrimental to the birds. According to NatureServe, populations are of concern in Arkansas, Mississippi, Oklahoma, and Tennessee.
- Frederick, P. C., and D. Siegel-Causey. 2000. Anhinga (Anhinga anhinga). In The Birds of North America, No. 522 (A. Poole and F. Gill, eds.). The Birds of North America, Inc., Philadelphia, PA.