Jacanas: Jacanidae

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JACANAS: Jacanidae

PHEASANT-TAILED JACANA (Hydrophasianus chirurgus): SPECIES ACCOUNTS
AFRICAN JACANA (Actophilornis africanus): SPECIES ACCOUNTS

PHYSICAL CHARACTERISTICS

Jacanas (juh-KAH-nuhz) vary from about 6 to 23 inches (15 to 58 centimeters) in length and from 1.4 to 9.7 ounces (40 to 275 grams) in weight. Jacanas have long, slender necks and extremely long toes and claws, as long as 4 inches (10.2 centimeters) in certain species. Their large feet allow them to balance on and move over lily pads and other floating vegetation, a practice that has given the jacana nicknames such as "lily trotters" and "Jesus birds." Jacanas also have bony spurs that jut out from their wings. These are used in battles with other jacanas, as well as to defend individuals from potential predators, animals that hunt them for food. Jacanas are unusual among birds in that the females are larger than the males, weighing, in some cases, as much as 60 percent more.

Jacanas are generally black or reddish brown in color. Most species have very bright wings and will sometimes spread their wings suddenly to frighten off potential predators. Jacanas also have bright patches of feathers on their foreheads. Male and female jacanas have similar coloration. Young jacanas, however, generally have brown backs and pale bellies, colors that allow them to blend into their environments well. Chicks develop adult coloration after about a year.


GEOGRAPHIC RANGE

Jacanas are found in the Old World and New World tropics, including parts of Central America, South America, Africa, Asia, Australia, and Madagascar.

HABITAT

Jacanas inhabit aquatic environments such as marshes or ponds in open (rather than forested) areas. They prefer water bodies that are covered in vegetation, since they use floating vegetation for both feeding and shelter. Jacanas have also been found in flooded pastures or rice fields.


DIET

Jacanas eat primarily insects. They forage, or search for food, by floating on water lilies or other vegetation and turning over the large leaves with their long toes. They then eat the insects or seeds caught in the water lily's roots. Jacanas also forage for seeds among the blades of marsh grasses. Rarely, they will eat larger prey such as small fish.


BEHAVIOR AND REPRODUCTION

Most jacanas do not migrate, but remain in the same place year-round. During the breeding season, they are generally found in pairs or small groups. During the non-breeding season, jacanas congregate in flocks of as many as several hundred individuals.

Jacanas are good swimmers and divers and frequently move into water to escape potential predators. In several species, jacana chicks have breathing holes at the ends of their bills that allow them to hide with most of their bodies underwater. The jacanas' swimming skills are particularly important during the molting season, when jacanas lose their flight feathers and are temporarily flightless.

DOMINANT FEMALES

Jacana females are much larger than the males and are dominant over them. A single female breeds with up to four males during the breeding season, defending a large territory against other jacana females. Males are responsible for building the nest, sitting on the eggs, and caring for the chicks once they hatch. Females show their dominance to males by pecking at their necks and backs. To show his submission, the male crouches and lowers his head.

A single female jacana mates with multiples males, usually between one and four. This breeding system, which is not very common in birds, is known as polyandry (PAH-lee-an-dree). The female jacana is significantly larger than the males and is responsible for defending the territories of her mates. When another female approaches, males call to their mate. Disputes between female jacanas are usually resolved using displays in which the wings are spread, showing off the sharp wing spurs, followed by physical fights if necessary. Physical fights involve jabbing with either the bill or the wing spurs. If the intruder succeeds in chasing off the original female, she will generally kill any chicks from the previous matings so that the male jacanas will be free to tend new sets of eggs. The new female will also peck at the male's neck and back to show her dominance. Males crouch and lower their heads in response. Jacana territories are usually about the size of half a football field.

Jacanas generally breed during the rainy season. Males begin by building several potential nest sites. The female decides which to lay eggs in, or chooses a new site within the territory for a nest. Jacana nests typically consist of water lily leaves or other plant material on top of a mat of floating vegetation. The male and female flash their wings at each other before mating. Males are responsible for incubating, or sitting on and warming, the eggs. Generally, four eggs are laid at a time, and chicks hatch after twenty-two to twenty-eight days. Males are responsible for feeding the chicks and for protecting them. Males call to the chicks when there is danger and settle them under the wings. Males will also sometimes fake a broken wing in order to attract the attention of predators and allow the chicks to escape. Numerous predators prey on young jacanas, including the purple gallinule (a rail of the family Rallidae), snakes, otters, and turtles. Fewer than half of all jacana chicks make it out of the nest, and another half die before reaching adulthood.


JACANAS AND PEOPLE

Jacanas live close to humans in many parts of their range and are therefore well-known to them.


CONSERVATION STATUS

No jacana species are currently considered threatened. However, wetland habitats are being drained for agricultural or other human uses in many parts of the world. Other populations have suffered due to pollution from pesticides.

PHEASANT-TAILED JACANA (Hydrophasianus chirurgus): SPECIES ACCOUNTS

Physical characteristics: The pheasant-tailed jacana is the largest species in the group, measuring from 11 to 12.2 inches (28 o 31 centimeters) in length and weighing in at 4.8 to 8 ounces (126 to 231 grams). It has dark feathers with a yellow band around the neck and white wingtips. Males have long, brightly colored tail feathers during the breeding season.


Geographic range: The pheasant-tailed jacana is found in Asia, including portions of Pakistan, India, Nepal, Sri Lanka, Myanmar, China, Java, and the Philippines.


Habitat: The pheasant-tailed jacana inhabits marshes, ponds, and lakes with patches of floating vegetation.

Diet: The pheasant-tailed jacana eats primarily insects and other invertebrates, animals without a backbone.


Behavior and reproduction: Pheasant-tailed jacanas walk across floating vegetation with their large feet, only rarely taking to the air. They are polyandrous, with females having up to four mates at one time. Four eggs are laid by the female in each nest and hatch after twenty-two to twenty-eight days. Males are responsible for sitting on eggs and caring for chicks after they hatch. Fewer than half of all chicks survive to adulthood.


Pheasant-tailed jacanas and people: No significant interactions between pheasant-tailed jacanas and people are known.


Conservation status: This species is not considered threatened, although some populations in China and Taiwan have declined dramatically due to loss of wetland habitats. ∎

AFRICAN JACANA (Actophilornis africanus): SPECIES ACCOUNTS

Physical characteristics: The African jacana ranges in length from 9 to 12.2 inches (23 to 31 centimeters) and in weight from 4 to 9 ounces (137 to 261 grams). African jacanas have brown, black, and white feathers and a blue patch on the forehead.


Geographic range: African jacanas are found in Africa south of the Sahara desert.


Habitat: African jacanas inhabit marshes, ponds, and lakes with mats of floating vegetation.

Diet: African jacanas eat primarily insects, other invertebrates, and the seeds of aquatic plants.


Behavior and reproduction: African jacanas breed during the rainy season. Females defend territories and mate with as many as four different males. Four eggs are laid at a time and hatch after twenty-two to twenty-eight days.


African jacanas and people: No significant interactions between African jacanas and people are known.


Conservation status: The African jacana is not currently considered threatened. ∎


FOR MORE INFORMATION

Books:

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.

Web sites:

"Jacanidae (Jacanas)." The Internet Bird Collection. http://www.hbw.com/ibc/phtml/familia.phtml?idFamilia=52 (accessed on April 16, 2004).

"Family Jacanidae (Jacanas)." Animal Diversity Web. http://animaldiversity.ummz.umich.edu/site/accounts/classification/Jacanidae.html#Jacanidae (accessed on April 16, 2004).

"Jacanas." Bird Families of the World, Cornell University. http://www.es.cornell.edu/winkler/botw/jacanidae.html (accessed on April 16, 2004).

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