Darter
The Darter is a fairly common,
but localized resident. It is thick-necked and cormorant-like water
bird with straight, unhooked bill. They catch fish under water by
impaling them on their dagger-like bills, surfacing to swallow them.
They swim with the body mostly submerged, only the long head and
neck protruding above the surface, hence the popular name "snake
bird". Adult has lower neck rufous, upper neck dark brown with
a white line extending backwards from the bill. It has upperparts
with long and gold-buff plumes. The young bird, from nesting to
immature, is buff coloured.
The body feathers of the darter, like
those of the cormorants, become saturated when the bird dives so
that it retains only slight positive buoyancy. Thus, diving is not
particularly difficult and the bird can easily stay under water.
This advantage is offset by the fact that the bird loses body-heat
to the water much more rapidly than, say, a duck would. Therefore,
after a spell of fishing the darter must come out of the water,
dry itself and, if possible, absorb some heat from the sun. Like
cormorants the darter perches with wings outspread to dry. The birds
have a black skin, which facilitates heat absorption. Darters nest
in colonies at some distance from other species. The nest is a fairly
substantial platform of sticks and twigs about 50cm in diametre.
As nesting proceeds, the whole nest is "whitewashed" with
the birds' excreta. The chicks have incredibly long necks, which
they raise when the adult arrives with food. The food is carried
in the crop and regurgitated directly into the chick's bill.
Singly or in pairs, they are found
on large waters and rivers, being most frequent in the Okavango
Delta and Chobe regions.
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