The role of farm dams in the ecology of spur-winged geese (Plectropterus gambensis) on the Highveld, South Africa

This paper describes the use of farm dams by spur-winged geese (Plectropterus gambensis) on the Highveld of South Africa. Applications for mining rights on coal seams located under wetlands have increased, which raises the question whether the loss of the waterfowl habitat can be mitigated. Since the spur-winged geese were observed on natural wetlands and man-made farm dams, these birds were selected to determine whether they are compatible with dams. A transect of 145 km was traversed weekly with a vehicle from January 2013 to December 2014, to count geese on farmland at Heidelberg, Vaal Dam, Grootvlei and Balfour. The purpose was to describe (1) habitat use of geese on farmland, (2) the limitations of farm dams as offset habitats and (3) habitat improvement. The geese preferred natural wetlands over farm dams but foraged on arable land rather than natural grassveld. Spur-winged geese rest on farm dams during the rainy season, although these dams are not used for breeding or flightless moult and therefore can only be regarded as partial offset for natural wetlands. Increasing the area of shallows at the inflow of larger dams in open landscapes with fringing vegetation may encourage breeding. However, it may take 5–10 years for fringe vegetation to become established and attractive for breeding, meaning that an offset habitat cannot be created over the short term.