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APPENDIX TO THE MINING AND CONSERVATION OF THE MPUMALANGA LAKES DISTRICT STUDY BY:
Professor Terence McCarthy 1 , Professor Bruce Cairncross 2 , Professor Jan-Marten Huizenga 2 and Allan Batchelor 3
1: School of Geosciences , University of the Witwatersrand, Johannesburg ; 2: Department of Geology, University of Johannesburg ; 3: Wetland Consulting Services (Pty) Ltd.
BIRDLIFE AT LAKE CHRISSIE
The birds frequenting the pans around Lake Chrissie were studied on a monthly basis over a period of eight years from 1996 to 2004. This was done by selecting samples of 15 pans and 3 lakes and studying these as being representative of the 300 pans in the area. The pans and lakes range in size from 1043ha in the case of Lake Chrissie to 2 or 3ha in the case of the smallest grass pans.
In dry years (<450mmpa) 80% of the pans dry up whereas in normal to wet years (>750mmpa) most of the pans retain their water throughout the year. In the flood years of 2000 and 2002 the Koolbank road (running along the eastern border of Lake Chrissie ) was flooded for 18 months causing a major inconvenience to some 12 farmers. The birds are counted by circumnavigating the pans in a 4 x 4 vehicle. However many of the study pans were inaccessible for months during the floods.
Two of the fifteen pans (in the study area) are reed covered which apart from providing cover for skulking birds such as night herons, crakes, rails and swamp hens, the reeds also provide roosts and nesting sites for cormorants, egrets, glossy ibises, spoonbills and swallows. The pans and lakes that are redlined are either open water, sedge lined largely grass covered or saline. To date 78 different species have been recorded in the study area. The monthly survey entailed counting over a million birds over the 8 year period.
In the dry years the predominating birds are flamingoes, Cape Teal , Avocets and migrant waders. In contrast in the wet years – the predominant birds are grebes, Egyptian and Spurwing Geese, Yellow-billed Duck, Pochard, Coot, Glossy Ibis and Stilts. The two geese are the most numerous birds on Lake Chrissie . It should be borne in mind they feed and breed on land and only moult and preen on the pan edges.
Lake Chrissie's panveld is unique in terms of occurring in a high rainfall area (743 mmpa average over 55 years) and in the highlands of the northern most extensions of the eastern Drakensburg giving run to the Usutu, Komati and Vaal rivers while the lakes have inlet and outlets and are considered to reflect a relict drainage system, the pans are generally grasslined, circular in shape and have no obvious inlets or outlets.
The most sought after birds are the Crowned Crane, Blue Korhaan and Chestnut-banded Plover – the latter is normally only found on the dry pans in the western Free State and northern Cape. The latest new records for the area are Yellow-billed Stork, Western Marsh Harrier, Asiatic Golden Plover, Lesser Sandplover, Redshank and Curlew.
According to Marius Wheeler of the Avian Demography Unit at the University of Cape Town, the MLD qualifies as a Global Important Bird Area.
Dr J de Villiers
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