The Nature Writers of Texas

The best nature writing from the newspaper, magazine, blog and book authors of the Lone Star State . . .

Thursday, June 25, 2009

White Ibis is a long-legged water bird
by Ro Wauer

An adult white ibis is a very clean-cut, distinct bird, although young of the year are rather ratty looking. Adults possess all white plumage except for black wingtips and a bright red face and long curved bill, with a blackish tip, and long red legs. The adult plumage gives them a rather royal appearance. The plumage of young birds is mottled with brown, although they too possess a reddish bill and legs. It is not too unusual this time of year to see adults and youngsters together, feeding in shallow water along the coast or at inland wetlands, such as mudflats and flooded pastures, or flying about in family groups. They are one of our more social birds, feeding and roosting together, sometimes in rather large colonies.

Ibis are waders that glean their food with their long curved bill, either in water or on more solid ground. Their diet consists primarily of crabs, crayfish and snails, but they also will take fish and snakes and almost any small creatures, including insects, that they find. Feeding behavior is rather interesting. Kent Rylander, in his “Behavior of Texas Birds,” wrote that “they walk leisurely through the shallows, sweeping their long, decurved bills from side from side as they probe the bottom mud for crustaceans (especially crayfish), worms, and other animals.” He also states that “this ibis is a nonvisual, tactile forager: it places its partially opened bill in the water or bottom sediment, then snaps it shut when it partially detects prey. Prey taken from the water’s surface, mud, or short grass habitats are generally located by sight. White Ibises also steal food items from one another.”

Nesting birds often gather in huge, dense colonies with as many as a thousand or more nests. One colony on Galveston Islands contained 20,000 breeding pairs in 2001. Most nests are built with numerous sticks, lined with green leaves, in low shrubbery, but other nests may be placed higher on low trees around water areas. Nests may be usurped by their neighbors, and a colony can raise a great racket when squabbling among themselves. Young leave the nests in about three weeks and follow the adults to choice feeding sites.

White ibis are primarily found in Texas along the Gulf Coast, but they are casual visitors considerable distances inland. They even are considered accidental in the Trans-Pecos. In recent years, breeding birds have expanded their range further inland. Generally, white ibis in Texas can be expected only during the summer months, but they seem to be staying all winter long more and more often.

Three species of ibis occur in Texas: white, white-faced, and glossy. And the roseate spoonbill is closely related, all within the family Threskiornithidae. White and white-faced ibis are reasonably common in wetlands in the Golden Crescent, but glossy ibis, a bird that once was found only along the eastern Gulf Coast, is gradually increasing in numbers. And the roseate spoonbill is far more numerous along the coast, rather than venturing very far inland.


At 8:47 AM, Anonymous Serena said...

Pretty helpful material, much thanks for this article.


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