Sunday, 23 December 2012

Gambian Waterbirds

Here are a few more images from The Gambia: starting with the world's largest heron, the Goliath, in the act of taking off, and showing off its 2.2 metre wingspan. That's over 7 ft., an almost sky-darkening sight! We were slowly moving through the Tendaba mangroves in a pirogue (a large canoe hued out of a single tree-trunk) when we came across the heron, resting in a tree-top as it was high tide. The Goliath Heron is well distributed throughout Sub-Saharan Africa. It nests during the rains, usually 3 metres or less up in a tree or bush, on a platform of sticks and reeds. Three eggs are laid, which hatch after 27 days. 

On the same boat-trip, we saw this Hamerkop with nesting material. Hamerkops are aberrant storks, in a family of their own. They build huge domed nests with a circular entrance, usually 1.5 metres across and almost as tall. In most parts of Africa, the Hamerkop is regarded with great respect and rarely suffers any persecution. There are many local myths about the disasters that can follow from harming a Hamerkop. The name is Afrikaans for 'hammer-head.'

Jacanas are a fascinating family of birds, found in all continents except Europe and Antarctica. In 7 of the world's 8 species, the male is the sole carer of nest, eggs and young, (the exception being the uncommon Lesser Jacana of Africa). They all build floating nests, typically on water-lilies, on which the female lays four large and shiny eggs. The male starts incubating when the clutch is complete, so that the chicks hatch (fully feathered and ready to walk and feed) at the same time.  Now his role becomes one of protecting the young by seeing off predators, and leading the brood to suitable feeding grounds. Meanwhile the female, unencumbered by family responsibilities, is free to seek a new mate: a strategy known as polyandry. This African Jacana looks more shaggy and unkempt than usual: it has probably just dried off after a bath, and is about to undergo a long preening session. 

Perhaps the most sought-after species for birders visiting The Gambia is the Egyptian PloverThis exquisite wader, which breeds in Senegal and spends the dry season here, is a must for anyone with a camera. The Greek historian Herodotus first described their habits in the 5th century B.C.: he wrote that on the banks of the Nile one type of bird would enter the open mouths of the crocodiles and pick out flesh from between their teeth. Hence the name: but now their breeding range is from Senegal to Sudan. It only became extinct in Egypt in the first part of the 20th century. 

We saw Collared Pratincole on only one day, and in one place: but at the Kaur Wetlands we came across a flock of over a thousand. Pratincoles are an interesting group of waders, most closely related to coursers - a strange fact in itself, as pratincoles are mostly aerial, and coursers terrestrial. The word comes from the Latin pratum, a meadow, and cola, inhabitant. Pratincoles are elegant aerial feeders, hawking for insects like a small tern or an overgrown swallow. They nest in colonies on the ground. It is unknown whether the Gambian non-breeding flocks nest in Europe or Africa, but there are wet-season colonies in Northern Senegal. 

The Senegal Thick-knee is a very common wader in The Gambia, both along the coast and inland. At Kaur we found  flocks of them with the pratincoles. They are in the same genus as the Stone Curlew which nests in southern Britain in small numbers. The large eye gives a clue to its habits: it is nocturnal and crespuscular (active at dawn and dusk). The world has nine species of thick-knees, ranging from Mexico in the west to Australia in the east. In South Africa they suffer from a bad press: not only thick-knee but 'thick head' too - there they are known by the Afrikaans name dikkop.

 Along the Gambian coast we found impressive flocks of gulls and terns. The fishermen use small boats to unload their catches onto the beaches - a truly sustainable artisan fishery. The beaches and lagoons near these fishing villages attract gulls, terns, and reef herons, all year round.  The photo shows a Caspian Tern in its non-breeding plumage: when nesting, the forehead, crown and nape are all black. Some flocks numbered hundreds, with lesser numbers of Royal Terns, Grey-headed Gulls, and a few Kelp Gulls which have recently spread up the coast from the south. 

Many thanks again to Roger and Yvonne for the photos: in my next post, I will put up my own Gambian shots - people and landscapes for a change, rather than wildlife! 

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