|Copyright: Natley Prinsloo (Mamagolo2)
|Date Taken: 2011-09-17|
|Exposure: f/4.5, 1/500 seconds|
|More Photo Info: [view]|
|Photo Version: Original Version|
|Date Submitted: 2011-09-18 1:33|
|[Note Guidelines] Photographer's Note|
What a fantastic 2 hours I had taking photo’s on the dams at the mine. The dams have abundant bird life and if it was not for the noisy Mahindra we rode with I would have been able to get more and better photos of the birds. Fortunately for me that the game guard who accompanied me there was a very good nature lover and many times he would free the Mahindra down to the edge of the dams just so I could get some good pics.
Enjoy and comments are welcome.
White-breasted Cormorants occur along the entire southern African coastline, and is common in the eastern and southern interior, but occurs only along major river systems and wetlands in the arid western interior. The coastal population breeds from Ilha dos Tigres in southern Angola, to Morgan Bay in South Africa. In 1977-81 there were 2 524 pairs breeding along the coast between northern Namibia and the Eastern Cape Province. Currently, the overall breeding population in southern Africa is estimated at 3 700 pairs, representing some 11 000 individuals, of which approximately half is entirely non-marine.
Along the coast, White-breasted Cormorants occur mainly within 10 km offshore, often near reefs. Inland populations frequent rivers, streams, dams and impoundments with adequate fish populations. A variety of nesting habitats are used, including offshore rocks and islands, cliffs, trees, reeds and man-made structures such as disused jetties, marine platforms, shipwrecks and pylons. Such artificial structures are used by over half the coastal population for breeding. The birds nest singly or colonially, occasionally utilising the same nests year after year. White-breasted Cormorants that forage in the marine environment feed on bottom-living, mid-water and surface-dwelling prey of little or no commercial importance, such as Sparids.
Changing water levels in the interior of southern Africa results in nomadic movements of White-breasted Cormorants, with distances of up to 1 054 km covered by young birds, as evidenced by ring recoveries. Inland (freshwater) and coastal (marine) populations interchange in both directions. Birds have been shown to move from Barberspan, South Africa, over 900 km away to Gazangula (Zambia), Bulawayo (Zimbabwe) and the Orange River estuary.
Human disturbance poses a serious threat at breeding sites. These cormorants are more susceptible to disturbance than the other marine cormorants, and leave their nests for extended periods if disturbed, exposing eggs and chicks to Kelp Gull predation. Black-backed Jackals and Cape Fur Seals occasionally take adult White-breasted Cormorants as prey. Other mortality factors include Avian Cholera, oil pollution, discarded fishing line and deliberate killing by humans inland.
A co-ordinated census of breeding White-breasted Cormorants at all southern African colonies, both coastal and inland, is necessary to obtain an accurate population estimate.
Source: Avian Demography Unit
Department of Statistical Sciences
University of Cape Town
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