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Storks - American storks

bill birds wood nest

Storks are large wading birds of the tropics and subtropics. They belong to the order Ciconiiformes, which A white stork and its nest in Turkey. JLM Visuals. Reproduced by permission. also includes the ibises and spoonbills. Storks are in the family Ciconiidae.

Unlike most tall wading birds, storks will perch in trees. They also nest in high places, and often return to the same nesting site year after year. These tendencies have long made the white stork (Ciconia ciconia) a favorite among villagers of Europe, who look forward to the annual return of these birds after wintering in Africa. Folklore that children are delivered by these birds, as well as other tales about storks, were brought to America by European settlers.

Storks look somewhat like cranes, but their bill is considerably longer and heavier. Most species have a straight bill. Cranes have three front toes like most birds, but storks have an additional toe at the back of the foot that lets them cling to a branch when perching. Herons and egrets also have this special toe.

Storks fly with their neck outstretched (except for the adjutant storks; Leptoptilos spp.). Storks have broad, strong wings that allow them to soar easily for long periods on rising warm air currents. The different species are often distinguished by the color of their bill and the bare skin on their head and legs.

The bill of a stork can be up to 9 in (23 cm) long and 7 in (18 cm) around at the thick base. Storks are adept at using their beak, to build a nest, find food, care for the young, and in fighting. The saddle-bill stork (Ephippiorhynchus senegalensis) of Africa has a vivid orange beak with a wide black band around it. It also has orange anklets at the bend in its legs (which are actually its ankles). The Asian open-bill stork (Anastomas lamelligerus) of India and Nepal has a beak in which the two mandibles do not close in the middle, which is an adaptation to capturing its specialized diet of freshwater mussels. The bill of the whale-headed stork (Balaeniceps rex) of freshwater swamps in Africa, from Sudan down through Zaire, is thick, rounded, spotted, and hooked on the end. However, this large gray bird is not a true stork; it is in a related family of its own, the Balaenicipitidae.

All storks (except the wood stork) study the ground or water intently when looking for food. Their keen eyesight and fast reaction time lets them quickly grab moving animals.

The adjutant storks of India eat carrion so they do not have to chase their meal. The greater adjutant (Leptoptilos dubius) and the lesser adjutant (L. javanicus) can be found along with vultures feeding at the leftovers of the kills of large predators. However, the adjutants do not tear meat off the carcass; they steal bits from the vultures. The marabou stork (L. crumeniferus) of the African savanna is also a carrion thief. Not an attractive bird, the marabou stork has a splotchy head, short neck, and a huge pink pouch hanging from its neck. The soft feathers on the tail of Leptoptilos storks have been used for hat decorations.


The only stork of North America is the wood stork (Mycteria americana), sometimes called the wood ibis. The wood stork has white body feathers, black flight feathers, gray legs, and a blue-gray featherless head. Its 9-in (23-cm) bill is gray, and it curves downward slightly at the end.

The wood stork lives primarily in the swamps of southern Florida, where it breeds in stands of large bald cypress trees. It also occurs more widely in Central and South America. In Florida, however, many of its nesting trees have been cut down, and wood stork habitat has also been destroyed or damaged by agricultural activities and drainage. In the 1950s, these birds were seriously threatened, until the Corkscrew Swamp Sanctuary was designated to protect a large nesting population. Their population, however, is still seriously depleted.

Wood storks feed primarily on fish, plus small frogs, reptiles, crustaceans, and mollusks. They use their feet and their bill to feel for the presence of food, which they snap up in their beak. They rarely depend on sight when hunting. Some wood storks also feed in open fields, where they hunt for insects in newly turned soil.

Wood storks do not mate so much according to the season, as to the level of water in their swampy habitat. They raise their young during the dry season, when their wetlands concentrate into prey-rich pools. These dense food supplies makes feeding hungry young storks easier. At the proper time, the male selects a nesting site, usually in a large bald cypress. At first, any female approaching the nest is driven away, but eventually he accepts a mate. The female holds the chosen nesting site while the male collects sticks as nest-building material. The female lays 2-5 eggs, but incubation starts as soon as the first one is laid. The eggs hatch after about 30 days of incubation by both birds. The fluffy white young remain in the nest until they are fully feathered, about 55 days after hatching.

The nest can be a dangerous place. Adolescent storks are prone to an activity that has been likened to that of juvenile gangs of humans. Groups of immature storks, younger than the age of three years, will attack nests, trying to drive the parents away. Then they tear apart the nest and kill the young. If this happens, the parents will build another nest and lay more eggs.

The only other American stork resides in tropical wetlands in South America. The jabiru (Jabiru mycteria) is among the largest storks, and can stand as tall as a human. Except for its head and neck, which are black and red, its plumage is white. The wings may span 7 ft (2.2 m) or more. Its 12-in (30-cm)-long bill is also black. The name jabiru is also sometimes given to the saddle-billed stork of Africa.

All large birds are in danger from hunters, and storks have the added problem of losing much of their wetland habitat to development. The presence of white storks on the rooftops of Europe has long been considered good luck. However, the numbers of these famous storks have dropped by about 90% in the last hundred years. Several changes explain this loss, including the effects of pesticides, loss of nesting and foraging habitat, changing climatic conditions, hunting, and the intensification of agricultural management (which degrades foraging habitat of the storks). Most species of storks are threatened by similar environmental changes associated with human activities.


Resources

Books

Sibley, David Allen. The Sibley Guide to Birds. New York: Knopf, 2000.


Jean F. Blashfield

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