Kafue lechwe antelope (Kobus leche kufuensis) inhabit a wetland area of the Kafue Flats in southern Zambia and have seasonal peaks in mating and calving. The construction of a hydroelectric scheme has recently altered the time of year when flooding starts, and there has been a corresponding change in peak mating and calving dates. In this study, Kafue lechwe mated mainly during the dry part of the year when grass quality and quantity was at its lowest and when water levels were increasing and thus inundating any potential food. As rising water levels corresponded with increases in numbers of oestrous females on leks (both before and after dam impoundment), and with increased mating rates in two other subspecies of lechwe (the black and red lechwe), floods appear to act as a proximate cue for the initiation of mating. Mating during rises in water levels results in most calving occurring seven months later (the gestation period) when the floodwaters are receding and exposing optimal forage, irrespective of the time of year, and this increases the survival of the lactating mothers and their calves.