The tropical zone of planet Earth contains many wonderful species which have adapted over time to their environment. The Jaçana (the c is pronounced like the one in
façade) consists of eight species; all are found within the tropical zone and all in possession of something quite special which equips them take best advantage of their habitat. At home in shallow lakes with lots of vegetation, the Jaçana has evolved enormous feet and claws. They are, literally, the big foot of the bird world. Once seen, never forgotten.
The vegetation which floats upon many shallow lakes in the world’s tropical zone contains a veritable smorgasbord for any bird able to reach them. Most are home to a huge variety of insects and other invertebrates. Yet the vegetation which houses this feast is what disables access to it. Now, if only a bird could walk on the vegetation without submerging it (and itself) with the weight, all this food would be theirs for the taking. Enter the Jaçana.
Tens, maybe hundreds of thousands of years ago the Jaçana looked quite different, at least in terms of its feet. Those with slightly larger feet which enabled them to distribute their weight over the vegetation and stand on it obviously did better than those with smaller feet. These more successful birds would attract mates more easily and pass on their genetic traits to their offspring. As one generation succeeded another, these traits became more and more refined to their habitat. In the case of the jaçana that meant their feet and claws became gradually larger and larger. Standing turned in to walking.
This is the wonder of evolution, the processes which change the inherited characteristics of biological populations over consecutive generations. One cannot only guess but the
theory (here meaning a well-substantiated explanation of some aspect of the natural world) must surely have made Darwin, on occasion, sit back, stretch and grin like an idiot. There may then be some irony in one of the jaçana’s other names, the
Jesus bird, so named after the passage in the Bible where Jesus walked on water.
Eight distinct species of Jaçana are found throughout the world’s tropical zone, three in Africa, three in Asia and Australasia and two in the middle Americas. Seven of the species are sedentary which means that they spend their entire lives in the vicinity of where they were born.
They are not terribly strong fliers as
something always seems to get in the way of perfect aerodynamics. However, a single species, the Pheasant-tailed Jaçana (above) journeys from the north into peninsular India and the rest of southeast Asia.
The jaçana hunts by stalking delicately across the lily pads. although if it finds a quicker route it will use that.
When it senses movement it then uses its bill to turn over the lily pads. However, they will occasionally use their toes as a turning tool too. Although they can swim very well they seem to prefer to walk and will only dive in to the water when needs dictate that they must. This can sometimes be when they sense a predator nearby and they will then send out a noisy alarm to warn others of the danger.
It is also known as the lily trotter which aptly describes in a name how the bird canters from lily pad to lily pad in its quest for food. Not only did they evolve to suit their environment, they decided to take up residency there. The jaçana builds its nest somewhat precariously atop of the vegetation, its eggs camouflaged to blend in with the plant life around it.
Only one species of jaçana (the lesser jaçana) is monogamous. For the other seven species, once the eggs have been laid, mother leaves the father to incubate the eggs and to raise the chicks while she looks for another suitable male with which to produce her next clutch. Dad has a secret weapon.
If the nest begins to sink or he feels the eggs or chicks are endanger he will tuck them under his wings or place them in his beak (above) and carry them to another site. If they are lost or killed then mom will return to replace them with a new clutch.
The chicks are precocial, which is a terms meaning that they are relatively mobile and mature from the get go. The male can teach them how to forage and hunt very quickly and some chicks leave his care after only forty days.
The jaçana – once seen, never forgotten.
First Image Credit Flickr User Anro Meintes
