Roseate spoonbill

Taxonomy

A 2010 study of mitochondrial DNA of the spoonbills by Chesser and colleagues found that the roseate and yellow-billed spoonbills were each other's closest relatives, and the two were descended from an early offshoot from the ancestors of the other four spoonbill species. They felt the genetic evidence meant it was equally valid to consider all six to be classified within the genus Platalea or alternatively the two placed in the monotypic genera Platibis and Ajaia, respectively. However, as the six species were so similar morphologically, keeping them within the one genus made more sense.

Description

The roseate spoonbill is 71–86 cm (28–34 in) long, with a 120–133 cm (47–52 in) wingspan and a body mass of 1.2–1.8 kg (2.6–4.0 lb). The tarsus measures 9.7–12.4 cm (3.8–4.9 in), the culmen measures 14.5–18 cm (5.7–7.1 in) and the wing measures 32.3–37.5 cm (12.7–14.8 in) and thus the legs, bill, neck and spatulate bill all appear elongated. Adults have a bare greenish head ("golden buff" when breeding) and a white neck, back and breast (with a tuft of pink feathers in the center when breeding), and are otherwise a deep pink. The bill is grey. There is no significant sexual dimorphism.

Like the American flamingo, their pink color is diet-derived, consisting of the carotenoid pigment canthaxanthin. Another carotenoid, astaxanthin, can also be found deposited in flight and body feathers. The colors can range from pale pink to bright magenta, depending on age, whether breeding or not, and location. Unlike herons, spoonbills fly with their necks outstretched. They alternate groups of stiff, shallow wingbeats with glides.

Behavior

This species feeds in shallow fresh or coastal waters by swinging its bill from side to side as it steadily walks through the water, often in groups. The spoon-shaped bill allows it to sift easily through mud. It feeds on crustaceans, aquatic insects, frogs, newts and very small fish ignored by larger waders. In the United States, a popular place to observe roseate spoonbills is "Ding" Darling National Wildlife Refuge in Florida. Roseate spoonbills must compete for food with snowy egrets, great egrets, tricolored herons and American white pelicans.

Breeding

The roseate spoonbill nests in shrubs or trees, often mangroves, laying two to five eggs, which are whitish with brown markings. Immature birds have white, feathered heads, and the pink of the plumage is paler. The bill is yellowish or pinkish.

Conservation and threats

Information about predation on adults is lacking. Nestlings are sometimes killed by turkey vultures, bald eagles, raccoons and fire ants. In 2006, a 16-year-old banded bird was discovered, making it the oldest known wild individual.