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