Limpkin

Appearance

The Limpkin is a somewhat large bird, 66 cm long, with a wingspan of about 102 cm and a weight of about 1.1 kg. The males are slightly larger than the females in size, but there is no difference in plumage. Its plumage is drab—dark brown with an olive luster above.

The feathers of the head, neck, wing coverts, and much of the back and underparts are marked with white, making the body look streaked and the head and neck light gray. It has long, dark-gray legs and a long neck. Its bill is long, heavy, and downcurved, yellowish bill with a darker tip.

The bill is slightly open near but not at the end to give it a tweezers-like action in removing snails from their shells, and in many individuals the tip curves slightly to the right, like the apple snails' shells. The white markings are slightly less conspicuous in first-year birds. Its wings are broad and rounded and its tail is short. It is often confused with the immature American White Ibis.

Distribution

The Limpkin occurs from peninsular Florida and southern Mexico through the Caribbean and Central America to northern Argentina. In South America it occurs widely east of the Andes; west of them its range extends only to the Equator.

Behavior

Limpkins are largely nocturnal and crepuscular, except that in Florida refuges, where they do not fear people, they are active during the day. Even so, they are usually found near cover.

Because of their long toes, they can stand on floating water plants. They also swim well, both as adults or as newly hatched chicks, but they seldom do so. They fly strongly, the neck projecting forward and the legs backward, the wings beating shallowly and stiffly, with a jerky upstroke, above the horizontal most of the time.

Habitat

It inhabits freshwater marshes and swamps, often with tall reeds, as well as mangroves. In the Caribbean, it also inhabits dry brushland. In Mexico and northern Central America, it occurs at altitudes up to 1,500 m. In Florida the distribution of apple snails is the best predictor of where Limpkins can be found.

Reproduction

Males have exclusive territories, which can vary in size from just 0.15 to 4 hectares. In large uniform swamps nesting territories can often be clumped together, in the form of large colonies. These are vigorously defended, with males flying to the territory edges to challenge intruders and passing Limpkins being chased out of the territory. Territorial displays between males at boundaries include ritualized charging and wing-flapping. Females may also participate in territorial defence but usually only against other females or juveniles. Territories may be maintained year-round or abandoned temporarily during the non-breeding season, usually due to lack of food.

Limpkins may be either monogamous, with females joining a male's territory, or serially polyandrous, with two or more females joining a male. With the monogamous pairs, banding studies have shown that a small number of pairs will reform the following year.

Nests maybe be built in a wide varaiety of places, either on the ground, in dense floating vegetation, in bushes, or at any height in trees. They are bulky structures of rushes, sticks or other materials. Nest building is undertaken by the male initially, who will construct the nest in his territory prior to pair-bond formation. Unpaired females will visit a number of territories before settling on a male to breed with. Males may initially challenge and fight off prospective mates, and may not accept first-year females as mates. Pair-bond formation may take a few weeks. Courtship feeding is part of the bonding process, where males catch and process a snail and then feed it to the female.

The clutch consists of 3 to 8 eggs, with 5 to 7 being typical and averaging 5.5, which measure 6.0 × 4.4 cm. The egg color is highly variable. Their background color ranges from gray-white through buff to deep olive, and they are marked with light-brown and sometimes purplish-gray blotches and speckles.

The eggs are laid daily until the clutch is complete, and incubation is usually delayed until the clutch is completed. Both parents incubate the eggs during the day, but only the female incubates at night. The shift length is variable, but the male incubates for longer during the day. The male remains territorial during incubation, and will leave the clutch to chase off intruders; if this happens the female will return quickly to the eggs. The incubation period is about 27 days, and all the eggs hatch within 24 hours of each other.

The young hatch covered with down, capable of walking, running, and swimming. They follow their parents to a platform of aquatic vegetation where they will be brooded. They are fed by both parents; they reach adult size at 7 weeks and leave their parents at about 16 weeks.

Food

Limpkins forage primarily in shallow water and on floating vegetation such as water hyacinth and water lettuce. When wading they seldom go deeper than having half the body underwater, and never are submerged up to the back. They walk slowly with a gait described as "slightly undulating" and "giving the impression of lameness or limping", "high-stepping", or "strolling", looking for food if the water is clear or probing with the bill. They do not associate with other birds in mixed-species feeding flocks, as do some other wading birds, but may forage in small groups with others of their species.

The diet of the Limpkin is dominated by apple snails of the genus "Pomacea". The availability of this one mollusk has a significant effect on the local distribution of the Limpkin. Freshwater mussels, including "Anodonta cowperiana", "Villosa vibex", "Elliptio strigosus", "E. jayensis", and "Uniomerus obesus", as well as other kinds of snails, are a secondary food sources.