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Jacanidae

life science Maturity 11-13 Next article →

The jacanas are a group of tropical waders belonging to the family Jacanidae.

Jacana jacana walking in water
Jacana jacana walking in water

They live in warm, tropical regions across the world. These birds are famous for their unique ability to walk on floating vegetation. Because of this, people often call them "Jesus birds" or "lily trotters." They are essential members of their ecosystems, feeding on invertebrates in shallow lakes.

NorthernJacana
NorthernJacana

To survive on floating plants, jacanas have developed a very specific physical mechanism. They possess extremely elongated toes and long toenails. These long digits allow the bird to spread its body weight over a much larger surface area. This prevents them from sinking into the soft, semi-emergent aquatic vegetation. They use these toes to forage for food on the water's surface. Their diet consists mainly of insects and other invertebrates.

Bronze-winged jacana (Metopidius indicus)
Bronze-winged jacana (Metopidius indicus)

Jacanas show interesting differences between males and females, known as sexual size dimorphism. In this family, the females are typically larger than the males. Most species are polyandrous, meaning a female may maintain a harem of several males. This is a rare social structure among birds. While the females are larger, both sexes look very similar in their plumage. The lesser jacana is a notable exception, as it is monogamous.

Lesser Jacana, Microparra capensis, Chobe River, Botswana
Lesser Jacana, Microparra capensis, Chobe River, Botswana

Parental roles in jacana families are also quite unusual. The males are primarily responsible for the survival of the next generation. They build relatively flimsy nests on top of floating vegetation. These nests hold eggs that feature dark, irregular lines for camouflage. The males perform the incubation, which means they sit on the eggs to keep them warm. They often use wing-brooding to protect the eggs.

Jacanidae wing bones
Jacanidae wing bones

This wing-brooding process involves a specific anatomical adaptation. The male may have a broadened radius or a wider gap between the radius and ulna bones. This helps him hold the eggs securely between his wings and his body. In some species, males also carry young chicks under their wings to move them to safety. Young chicks have a unique way of hiding from danger. They can dive underwater and stay submerged with only their bills visible.

African jacana (Actophilornis africanus) Kenya
African jacana (Actophilornis africanus) Kenya

The study of these birds has a long history in science. French naturalists Jean-Charles Chenu and Marc des Murs introduced the family in 1854. They originally used the spelling "Jacaneinae." Later, in 1885, Leonhard Stejneger introduced the modern spelling, "Jacanidae." The name itself has a complex history. It comes from the Portuguese word "jaçanã," which is derived from a Tupi name, "ñaha'nã."

Pheasant tailed jacana 2016
Pheasant tailed jacana 2016

Today, there are eight known species of living jacanas. These species are organized into six different genera. Scientists have also discovered four fossil species from the Oligocene of Egypt and the Pliocene of Florida. Most jacanas are sedentary, meaning they stay in one place. However, the pheasant-tailed jacana is different. It migrates from the north into peninsular India and southeast Asia.

Irediparra gallinacea - Comb-crested Jacana
Irediparra gallinacea - Comb-crested Jacana

Jacanas have several distinct biological traits that separate them from other birds. They have ten tail feathers, while most other wader groups have twelve. Most species have five neck vertebrae, though the species *Hydrophasianus chirurgus* has six. Some species, like the African jacana, undergo a simultaneous moult. This is when they lose their flight feathers all at once. This process makes them flightless for a period, which relates to their ability to breed when rains arrive.

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🖼️ Images & Media (13)
File:Jacanidae wing bones.svg
Jacanidae wing bones.svg
File:Oystercatcher (Haematopus ostralegus) svg-element.svg
Oystercatcher (Haematopus ostralegus)...
File:Corroboree Jacana.jpg
Corroboree Jacana.jpg
File:Bronze-winged jacana (Metopidius indicus).jpg
Bronze-winged jacana (Metopidius indicus).jpg
File:Lesser Jacana, Microparra capensis, Chobe River, Botswana.jpg
Lesser Jacana, Microparra capensis, Chobe...
File:Pheasant tailed jacana 2016.jpg
Pheasant tailed jacana 2016.jpg
File:African jacana (Actophilornis africanus) Kenya.jpg
African jacana (Actophilornis africanus) Kenya.jpg
File:Irediparra gallinacea - Comb-crested Jacana.jpg
Irediparra gallinacea - Comb-crested Jacana.jpg
File:RostratulaCapensisDavies.jpg
RostratulaCapensisDavies.jpg
File:Larus argentatus Gould.jpg
Larus argentatus Gould.jpg
File:Jacana jacana walking in water.jpg
Jacana jacana walking in water.jpg
File:Madagascar Jaçana.jpg
Madagascar Jaçana.jpg

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