Rails, Coots, and Moorhens: Rallidae
RAILS, COOTS, AND MOORHENS: RallidaeBUFF-SPOTTED FLUFFTAIL (Sarothrura elegans): SPECIES ACCOUNTS
BLACK RAIL (Laterallus jamaicensis): SPECIES ACCOUNTS
CORNCRAKE (Crex crex): SPECIES ACCOUNTS
Rails are usually colored to blend into their environments. Browns, blacks, grays, and blue-gray shades are particularly common in the group. One group of gallinules, however, tends to have brighter colors such as purples, blues, and greens. Rails often have spotted, barred, or streaked patterns. The underside of the tail is frequently differently colored from the rest of the animal. Generally, females and males are similarly colored, with a few exceptions such as the flufftails and some of the New Guinea forest rails.
Rails vary in size from 4.7 inches (12 centimeters) and 0.7 ounces (20 grams) for the black rail, the smallest member of the family, to 24.8 inches (63 centimeters) and 9.2 pounds (4.2 kilograms) for the takahe, a large, flightless rail species. In most rails, males and females are similar in size. However, males are much larger than females in a few species.
The bodies of rails are often laterally compressed, flattened on the sides, a trait which allows them to move easily through dense vegetation. Many species have long necks. The wings of most rails are short, broad, and rounded. An unusually large number of rails are flightless, unable to fly. These are generally species found on islands that have no natural predators, animals that hunt them for food. Even some rails that are able to fly sometimes escape danger by running away instead of flying. Some rails also have a sharp claw on the wing that helps individuals, particularly young rails, climb. Rails generally have short tails. Bills vary a lot among the rails, and may be long or short, straight or downwardly curved, and thick or thin. Bill shape depends primarily on diet. Rails have strong legs and feet. In some species the legs are rather long.
Rails are found worldwide except in the Arctic and Antarctica, and in very dry deserts. They are particularly common on oceanic islands. In part, this is because of their weak flying abilities, which causes them to be easily thrown off course.
Rails live in a wide variety of habitats, including wetland, grassland, scrub, and forest. Wetlands have the largest number of rail species, although many species are also found in rainforests. Both freshwater and coastal saltwater wetlands are used by rails. Coots are the most aquatic rails and live in freshwater habitats such as lakes and ponds. Rails that live in forested areas can inhabit diverse forest types with almost any type of ground cover, either clear, with leaf litter, with mud, or covered with dense vegetation.
Rails are omnivorous, meaning they eat both plant and animal matter. The more aquatic rails, such as coots and gallinules, tend to eat primarily plant matter, whereas wetland and terrestrial rails tend to have a diet consisting mostly of animal matter. Animal matter eaten by rails can include insects, spiders, worms, mollusks, crustaceans, and sometimes small fish, frogs, tadpoles, lizards, snakes, or turtle hatchlings. Rails will also eat the eggs or chicks of other birds. Some rails even eat carrion, dead animal matter. Plant matter eaten by rails can include fruits, seeds, stems, leaves, tubers, roots, and, in some species, cultivated crops. Most rails are generalists, that is, they eat a wide variety of foods, concentrating on whatever food is most abundant at the time. However, there are a few specialists. The chestnut rail and rufous-necked wood-rail, for example, inhabit mangrove forests and eat mostly crabs.
BEHAVIOR AND REPRODUCTION
Most rails are solitary, meaning they live alone, although some can be found in pairs, usually male and female breeding partners, or in small groups. Some species, however, including most coots and some gallinules and moorhens, sometimes gather in large flocks during the nonbreeding season. The black-tailed native-hen, an Australian rail, can form flocks of as many as 20,000 individuals.
Breeding strategies vary across the rails. Many species are monogamous (muh-NAH-guh-mus), with one male mating with one female. Some species are polygamous (puh-LIH-guh-mus), meaning single males mate with multiple females. Other species are polyandrous (pah-lee-AN-drus), where a single female mates with multiple males. In some species, older siblings help their parents feed and care for younger siblings. Intraspecific brood parasitism is also common among the rails. This describes a strategy in which a female lays eggs in the nests of other females so that other individuals will feed and raise her young.
Many rails are territorial and will defend their territories from other individuals of the same species. To prevent serious injuries from actual fighting, territorial disputes between rails are decided using displays, characteristic postures or behaviors that help determine which individual would win in an actual fight.
Rails are shy, and generally stay in areas of dense vegetation. At night, they roost on the ground, hidden in dense vegetation, or, less commonly, in trees.
RAILS AND PEOPLE
Many species of rails have been and continue to be hunted either for food or for sport. Rail eggs are also sometimes collected and eaten. Some species of rails are considered pests because they damage crops. The purple swamphen appears in Egyptian wall paintings and was also considered sacred by the Greeks and Romans.
FLIGHTLESSNESS IN RAILS
Flightlessness is unusually common in rails, with 24 of the 134 rail species having lost the ability to fly. All flightless species occur on islands, particularly those where there are no natural predators. Flightlessness may be common in rails because they are weak fliers with a tendency to avoid predators by running rather than flying away. Flightless species usually have smaller wings and stronger legs than species that fly.
Of the 134 rail species in existence, thirty-three are considered threatened by the World Conservation Union (IUCN). Of these, four are Critically Endangered, facing an extremely high risk of extinction in the wild. Twelve are Endangered, facing a very high risk of extinction, and sixteen are Vulnerable, facing a high risk of extinction. One, the Guam rail, is Extinct in the Wild. No fewer than twenty rail species have become extinct since 1600, the majority of them flightless species on islands. Threatened species have suffered population declines due primarily to habitat destruction. Some island species have also been severely affected by the introduction of animals such as cats, dogs, pigs, mongooses, and snakes.
Physical characteristics: The male buff-spotted flufftail has an orange-chestnut head and neck and spotted body. The female is golden brown in color with a spotted back and barred belly. Buff-spotted flufftails range from 6 to 6.7 inches (15 to 17 centimeters) in length and 1.4 to 2 ounces (39 to 61 grams) in weight.
Geographic range: Buff-spotted flufftails are found in Africa from Guinea east to the Democratic Republic of the Congo and Uganda and south to northern Angola, as well as from southern Sudan and Ethiopia to South Africa.
Habitat: Buff-spotted flufftails are found in forests, but may also inhabit abandoned agricultural lands.
Diet: Buff-spotted flufftails eat primarily invertebrates, animals without backbones, such as insects and spiders. They forage on the ground.
Behavior and reproduction: Buff-spotted flufftails are highly territorial during the breeding season. Individuals are active during the day, although males sing to attract females at night, sometimes for as long as twelve hours continuously. Some buff-spotted flufftail populations migrate while others do not.
Buff-spotted flufftails are monogamous, and nests are built on the ground. Nests are dome-shaped and built from dead leaves or grass. The female lays three to five eggs at a time. Eggs hatch after fifteen to sixteen days, and the young are independent after nineteen to twenty-one days.
Buff-spotted flufftails and people: The buff-spotted flufftail's loud, hooting calls, which can last all night, are the source of local legends.
Conservation status: Buff-spotted flufftails are not threatened. ∎
Physical characteristics: Black rails are small, dark birds with a slightly reddish brown upper back and spots or bars on the lower parts of their backs and bellies. Females are slightly paler in color. Black rails range from 4.7 to 6 inches in length (12 to 15 centimeters) and from 0.7 to 1.6 ounces (20.5 to 46 grams) in weight.
Habitat: Black rails lives in marshes and moist grassland areas.
Diet: Black rails eat primarily small invertebrates such as insects and spiders. They will sometimes eat larger animals such as fish or tadpoles, as well as plant seeds.
Behavior and reproduction: Black rails are territorial during the breeding season. Some populations migrate while others remain in the same place throughout the year. Most black rails are monogamous, although in rare instances a male may breed with multiple females (polygamy). In the United States black rails breed in the summer. In other parts of its range breeding occurs during the rainy season. Black rails nest in low vegetation, where they build a bowl-shaped nest out of grass. The nest is covered with a woven canopy. Females lay anywhere from two to thirteen eggs at a time. Eggs hatch after seventeen to twenty days.
Black rails and people: No significant interactions between black rails and humans are known.
Conservation status: One black rail subspecies, found in the Peruvian Andes, is considered Endangered, while the others are considered Near Threatened. In the United States, black rail populations declined greatly during the twentieth century, due largely to habitat loss. ∎
Physical characteristics: Corncrakes are a blue-gray color on the face, neck, and breast. The backs are a streaked brownish color. They range from 10.6 to 12 inches in length (27 to 30 centimeters) and from 4.6 to 7.4 ounces (129 to 210 grams) in weight.
Geographic range: Corncrakes breed in Europe and central Asia, then migrate to northern and eastern Africa for the winter.
Habitat: Corncrakes inhabit grasslands during both the breeding season and the winter.
Diet: Corncrakes eat insects, spiders, and other invertebrates as well as seeds and grass. They look for food under the cover of vegetation, rather than foraging in the open.
Behavior and reproduction: Corncrakes are particularly active in the morning and at dusk, although males may call all night. Corncrakes are serially polygamous, meaning males mate with multiple females, but have only one breeding partner at a time. Nests are cup-shaped and built on the ground, usually hidden in dense vegetation. Six to fourteen eggs are laid at a time, and hatch after sixteen to twenty days. Only females incubate eggs. Chicks become independent at ten to twenty days.
Corncrakes and people: Corncrakes are hunted for food. They are particularly vulnerable during their migration.
Conservation status: Corncrakes are considered Vulnerable due to the loss of much of their grassland habitat areas. ∎
FOR MORE INFORMATION
del Hoyo, J., A. Elliott, and J. Sargatal, eds. Handbook of the Birds of the World. Vol. 3, Hoatzin to Auks. Barcelona: Lynx Edicions, 1996.
Perrins, Christopher, ed. Firefly Encyclopedia of Birds. Buffalo, NY: Firefly Books, 2003
"Rallidae (Rails and Coots)." The Internet Bird Collection. http://www.hbw.com/ibc/phtml/familia.phtml?idFamilia=46 (accessed on April 25, 2004)
"Family Rallidae (Coots and Rails)." Animal Diversity Web. http://animaldiversity.ummz.umich.edu/site/accounts/classification/Rallidae.html#Rallidae (accessed on April 25, 2004)
"Crakes, rails, coots, gallinules." Bird Families of the World, Cornell University. http://www.es.cornell.edu/winkler/botw/rallidae.html (accessed on April 25, 2004)