Anhingas (darters)

 

The Anhingidae family of birds is closely related to other families within the Sulae suborder, which includes gannets, boobies, cormorants and shags. However, the four species that comprise the Anhingidae show several features that set them apart from birds such as the cormorant to which they might, at first sight, appear to be similar.

 

The four species are the anhinga or American darter (Anhinga anhinga), the Oriental or Indian darter (Anhinga melanogaster), the African darter (Anhinga rufa) and the  Australasian or Australian darter (Anhinga novaehollandiae). They are long, slim water birds that inhabit tree-lined margins of freshwater lakes and rivers in tropical and warm temperate regions, only rarely being found in brackish waters. Their regional distributions are suggested by their names, but the differences between the species are not all that great. Indeed, they can almost be thought of as four subspecies of a widely distributed species, the anhinga or darter, which is also sometimes called the snakebird. Another name used in the United States is water turkey, which is strange in that any presumed resemblance to a turkey must be the product of a very vivid imagination! However, this may have something to do with the anhinga’s appearance on the Southern table as meat.

 

The anhinga is between 32 and 36 inches in length, which makes it similar in size to a cormorant, but their heads are slimmer, their bills longer and thinner and unhooked, their necks longer, and their body feathers thicker. Males and females are differently coloured, unlike cormorants. However, one feature that anhingas have in common with cormorants is that their flight feathers are relatively permeable to water, so they need to spread their wings to dry after they have been swimming. They also lack air sacs under the skin and have quite heavy bones, which is an aid when diving.

 

Female anhingas tend to be slightly larger than the males, but with smaller bills. Males have generally dark plumage with the females being lighter in colouring.

 

Anhingas are strong fliers, with steady and rapid wingbeats, but they glide and climb more than cormorants. They can sometimes be seen riding warm air currents several hundred feet up, with wings outstretched and necks and legs extended, thus forming a cross shape.

 

Anhingas from the northern part of their North American range will fly south for the winter, which is when they are sometimes found in more brackish waters.

 

Anhingas only enter the water to escape from danger or to feed. They can swim completely underwater, with nostrils closed, or with the body submerged and only the head and neck above the surface. This latter mode is what gives them the “snakebird” epithet.

 

The name “darter” is equally well deserved, as this refers to the bird’s method of catching their prey. The neck will be held in an S-shape and the rapier-like beak thrust suddenly forwards to spear a fish. This is then brought to the surface, tossed in the air, caught again and swallowed whole. Other prey includes frogs and salamanders, which are speared and then beaten to death against a rock. Crayfish and water insects also form part of the diet.

 

Anhingas nest in small colonies, often alongside ibises and herons. A bulky nest of sticks, lined with green leaves, is built in a bush or tree, anything from three to thirty feet above the water. The average clutch size is four eggs, although this can be as few as two or as many as six. Incubation, by both parents, can take up to four weeks, after which the chicks are fed by food regurgitated by a parent bird.

 

The chicks are born blind and naked, but are able to leave the nest when two weeks old, should the need arise. If danger threatens, a chick is able to fall into the water and swim ashore, although they are then very vulnerable to predators such as alligators. A chick can climb back to the nest by using its wings and neck as well as its feet.

 

Young anhingas fledge at six to eight weeks, staying close to the nest until they are ready.

© John Welford

Hamerkop

The hamerkop (Scopus umbretta) has a number of alternative names, including hammerhead stork, umbrette, tufted umber and anvilhead. It is the only member of the Scopus genus and Scopidae family, although it has posed a problem over whether this family should be classed with the order of Ciconiformes (which includes storks) or Pelecaniformes (which includes pelicans and herons).

The hamerkop shows some stork-like features, such as flying with its neck extended and its lack of powder down, but its voice organs are heron-like and it has teeth on the outer edge of its middle claw, which is again a heron-like feature. The consensus appears to be that the hamerkop represents one of the missing links between storks and herons, so its status in terms of order remains in doubt.

The hamerkop is a wading bird that is found in many parts of tropical Africa, Madagascar and southwest Arabia. It inhabits wetlands that include rice paddies, irrigation ditches or roadside pools, and will migrate locally as suitable environments appear and disappear.

Hamerkops have gained a measure of protection from the superstitions and legends that have arisen about them in some parts of their range. It is widely believed, for example, that harming a hamerkop will bring bad luck. To the bushmen of the Kalahari region, the hamerkop is the “lightning bird”, and robbing a hamerkop nest will increase one’s chance of being struck by lightning.

Appearance and behaviour

The hamerkop is about 20 inches long and resembles a heron in its overall shape, but with comparatively shorter legs. It is brownish in colour with glossy purplish tinges on the wings and back. Its large head is set on a somewhat short and thick neck. The long, flat and slightly hooked bill, coupled with the prominent crest on the back of the head, give the bird its name, as the head is not unlike the shape of the head of a hammer (hamer kop is Afrikaans for “hammer head”). 

The hamerkop behaves in rather peculiar ways from time to time. A small group may dance around each other for no obvious reason, calling loudly, before they appear to bow to each other, pull their heads back and resume standing silently apart. 

Hamerkops have a varied diet, including water insects, worms, molluscs, small fish and amphibians. They are often most active in the evenings and can also be nocturnal.

Breeding

The hamerkop’s most remarkable feature is its compulsive nest building, which even takes place outside the breeding season. The nest is a vast structure, as much as six feet in diameter, that is a flattened covered dome with a side entrance. A pair of hamerkops can spend several months building a nest, which can comprise as many as 10,000 sticks in its construction, and when it is finished they may start work on another. Great care is taken in decorating the outside of a nest with objects found by the birds, much as a magpie might do to the inside, these items being anything that is highly coloured and takes the birds’ fancy.

When breeding, the female hamerkop will lay three to six eggs deep inside the nest and both partners will incubate them in turn for up to 30 days. Both parents will feed the nestlings, who can be left alone for long periods while the parents look for food, secure in the knowledge that the fortress-like nest provides excellent protection. The young birds are ready to leave the nest at around 50 days but will continue to roost in it for several months longer.

Unused hamerkop nests are often taken over by other bird and animal species, including snakes, and sometimes a bird such as an eagle owl will eject a hamerkop pair from their nest, only for them to return when the squatter has finished with it. 

© John Welford

Jaçanas

 

Jaçanas are tropical and sub-tropical waders of the order Charadriiformes, comprising eight species divided between six genera. They are found in central and southern America, southern Africa, south-east Asia and northern Australia. Their preferred habitat is freshwater pools and lakes, where they are skilled at walking on lily leaves and other floating vegetation, thanks to their exceptionally long toes and claws.

The name jaçana came originally from the Tupi people of the Amazon basin, but is now a Portuguese word pronounced “zhasana” with the emphasis on the first and last syllables. Other names for these birds are “lily trotters” and “lotus birds”.

 

Appearance

The American, or northern, jaçana (Jacana spinoso), which is found in Mexico, the West Indies, and as far south as Panama, is about 10 inches in length and cinnamon-red in colour with greenish-yellow flight feathers. The head and neck are black and the head has a bright yellow frontal shield. This shield, similar to that found on coots and gallinules, is typical of jaçana species, as is the sharp spur on the bend of the wing that is used for fighting.

Other species vary in size, from the African jaçana (Actophilornis africana – see photo) at 12 inches to the pheasant-tailed jaçana (Hydrophasianus chirurgus, from Asia) that is 20 inches long thanks to its tail that is the same length as its body. The latter is also the most striking in appearance, with a bronze-brown back, black underparts, white face and neck, yellow nape and white wing patches. Although male and female jaçanas are similar in colour, the females are generally larger.

 

Behaviour

In flight, jaçanas resemble gallinules with their necks stretched forwards and legs trailing behind.

They are generally quiet birds, having a variety of grunts and whistles. However, when arguing over territory they can be much noisier as they scold and threaten each other with wings raised.

Their confidence in being able to walk on floating vegetation has made them approachable to quiet close distances. However, when alarmed jaçanas will either freeze or swim away. They can even dive if they have to.

Outside the breeding season, jaçanas congregate in small flocks and can be seen seen flying low over lakes and marshes. When they land, a typical behaviour is to stretch the wings right over the back until the tips nearly meet.

Jaçanas feed on insects, molluscs and small fish.

 

Breeding

A jaçana nest is a loose floating mass of vegetation that can easily drift in the wind. The usual clutch is four eggs which take around three to four weeks to hatch, with the male bird doing most of the incubating. He is also more active than the female in caring for the chicks when they hatch.

© John Welford