Spoonbills and Ibises
Roseate Spoonbill
The spoon-shaped bill is used to find food by feel and by taste in muddy water.
Roseate Spoonbill
The spoon-shaped bill is used to find food by feel and by taste in muddy water.
■ Finding food is one of the primary challenges faced by birds, and the large wading birds such as herons, ibises, and spoonbills show a wide range of strategies. Herons and egrets hunt entirely by sight (see this page). Spoonbills hunt entirely by touch. Ibises use both sight and touch. They often look for clues like crayfish burrows, then stick their bill in and probe around using their senses of touch and taste in the tip of their bill until they find something worth grabbing.
Feeding both by sight and by feel, White Ibis thrust their bills into mud or into burrows.
■ Regurgitation is normal and common in birds. All birds have an expandable sac at the base of their neck where the esophagus meets the body, known as the crop (see this page). Some digestion begins there, but it is mainly a food storage organ. Adult birds can gather a lot of food while they are out foraging, hold it in their crop as they fly back to the nest, then regurgitate it for the nestlings. Birds also regurgitate and discard indigestible parts of their food, such as seeds or shells. Some of these items are regurgitated because they are too large to pass through the intestines, others because it is helpful to remove the extra weight and bulk from the body as soon as possible.
A baby White Ibis (right) reaches in for food being regurgitated by the adult (left).
■ Why do birds stand on one leg? The short answer is: Because it’s easy for them. This behavior is most conspicuous in long-legged species, but all birds do it. Several adaptations of leg structure make this a stable and almost effortless stance. The center of mass of their body is below the knee (like a squatting position), and a knob on the pelvis prevents the leg from angling any higher. Balancing on one leg requires angling that leg so that the foot is directly below the body, and with the leg essentially locked in position, and the body leaning against the leg, tiny adjustments of the toes are all that is needed to stay upright. Birds also have an extra balance sensor near their pelvis, which undoubtedly helps them stay upright on one leg (see this page).
A White Ibis standing on one leg, from the side and from the front