ACTIVITY BUDGET OF BREEDING WHITE-FACED WHISTLING DUCKS DENDROCYGNA-VIDUATA ON STOCK-PONDS IN SEMIARID SOUTH-AFRICA, AND A COMPARISON WITH NORTH-TEMPERATE WATERFOWL

In the semi-arid regions of South Africa, stock-watering ponds and dam s have become an important aquatic habitat for several species of wate rfowl. We monitored the diurnal activities of breeding white-faced whi stling ducks Dendrocygna viduata on stock-watering ponds and dams asso ciated with the Nyl River floodplain, South Africa, from December 1992 to March 1993. Activity patterns diverge from those of north-temperat e breeding ducks; apparently a result of differences in environment an d resource availability. While most species of north-temperate breedin g ducks spend large portions of the day aquatic foraging, male and fem ale white-faced whistling ducks foraged on stock-ponds for only 4.0% a nd 9.8% of the day, respectively. white-faced whistling ducks were abl e to satisfy most of their daily dietary requirements during crepuscul ar foraging flights to neighboring Panicum schinzii fields. This permi tted them to spend most of the day in comfort-related activities (slee ping, leafing, preening) (males 49% of the day, females 67%), which pr esumably has important energetic implications for reproducing birds. L ow foraging effort is also indicative of a low aquatic resource availa bility on the stock-watering ponds studied, relative to north-temperat e wetlands. Thermal stress associated with high summer temperatures in South Africa apparently influenced daily activity patterns because fe eding, locomotion, courtship, and aggression were rarely observed duri ng the hottest parts of the day. While stock ponds provide limited for aging opportunities, they do supply habitat for comfort-related activi ties, a critical requirement of waterfowl.