Birds
Northern Jacana
Jacana spinosa · also called northern jacana, lily-trotter, jesus bird
The northern jacana is a wetland bird that has turned the usual bird family life upside down. The female is the big, aggressive one; she holds a territory containing several males and mates with all of them, and each male is then left to build the nest, sit on the eggs, and raise the chicks by himself. It does all this while walking across floating lily pads on a pair of absurdly long-toed feet.
Overview
Northern jacanas live in freshwater marshes, ponds, ditches, and rice fields from central Mexico through Central America and across parts of the Caribbean. They are about 24 cm long, chestnut with a black head, a yellow bill and forehead shield, and long grey legs ending in extraordinarily long, thin toes and claws.
Walking on lily pads
Those toes give each foot a huge span, spreading the bird’s weight across several floating leaves at once so none sinks. With a light, high-stepping gait the jacana forages far out on vegetation no heavier-footed bird could use — hence “lily-trotter” and “Jesus bird.”
Reversed roles
The female is about half again as heavy as the male and is the dominant, territory-holding sex. She defends a large area subdivided among up to four males, mating with each. Every male then builds a floating nest, incubates the four eggs alone, and guards the chicks, which can swim and dive within hours of hatching. A male can even carry small chicks tucked under his wings, their legs dangling, to move them from danger.
Status
The northern jacana is Least Concern, common wherever wetlands with floating plants persist, though local populations are lost to drainage and the removal of surface vegetation.
Northern Jacana: common questions
How does the northern jacana walk on water?
It does not walk on the water itself but on the floating plants that cover the surface of a marsh or pond, such as water lilies, water hyacinth, and lotus. The trick is weight distribution. The jacana has exceptionally long, slender toes and a very long hind claw, giving each foot a huge span. That span spreads the bird's body weight across a wide area and across several leaves at once, so no single leaf takes enough load to tip or sink. Moving with a light, high-stepping gait, the bird can forage right out in the middle of vegetation that no heavier-footed bird could use, which is why it is nicknamed the lily-trotter or Jesus bird.
Why do male northern jacanas raise the young?
The northern jacana has a mating system called sex-role reversal with polyandry. Females are larger and compete for territories and mates, and a successful female controls an area holding several males. Because she spreads her eggs among multiple partners, the workable division of labour is for each male to take full responsibility for one clutch. The male builds the nest, does all the incubation, and guards the chicks, while the female patrols the whole territory, fends off rival females, and provides replacement clutches if a nest fails. This lets the female convert a good territory into as many broods as possible, with the males doing the day-to-day parenting.
What do the chicks do when threatened?
Jacana chicks are precocial, meaning they hatch covered in down, with their eyes open, and able to walk, swim, and dive almost immediately. When the attending male gives an alarm call, the chicks may freeze flat against the vegetation, or slip into the water and submerge with only the bill tip exposed, or dive and swim away underwater. The father may also gather very small chicks under his wings and carry them bodily to safety, their long legs hanging down as he goes. This combination of hiding, diving, and being carried gives the brood several ways to escape herons, snakes, turtles, and large fish.
Is the northern jacana related to shorebirds?
Yes. Jacanas are members of the wader or shorebird order, the same broad group as sandpipers, plovers, and avocets, and they form their own family, the Jacanidae, found across the warmer parts of the world. Within that group they are specialised for a life spent almost entirely on floating freshwater vegetation rather than on mudflats or shorelines. The northern jacana is the species of Middle America and the Caribbean; its close relative the wattled jacana takes over in South America, and the two occasionally meet and hybridise where their ranges overlap around Panama.