The timing of births in buffalo, Grant's gazelle, and Thomson's gazelle was obtained from published data on fetuses and pregnancy rates (Walther 1972, Bradley 1977, Sinclair 1977a) and those of oribi and dikdik from observations of juveniles (Jongejan et al.
Dikdik, the smallest of these antelopes, produces two young per year.
The diet of each species was obtained either from our own observations or from the literature: for wildebeest (Watson 1969, Kreulen 1975), topi (Duncan 1975, Murray 1993, Murray and Brown 1993), buffalo (Sinclair 1977a), waterbuck (Field 1972, Spinage 1982), zebra (Klingel 1969), Thomson's gazelle (Gwynne and Bell 1968), kongoni (Stanley-Price 1978, Murray 1993), dikdik (Hendrichs and Hendrichs 1971), giraffe (Pellew 1980), and oribi (Mduma 1991, Mduma and Sinclair 1994).
Sample size for dikdik was too small to provide meaningful values and we do not consider this further.
This relationship is not evident with the five browsers and mixed feeders (Grant's gazelle, impala, oribi, dikdik, and giraffe).
There is a group of four species (topi, warthog, buffalo, and dikdik) with [J'.sub.births] [sim]0.5-0.7 and these are also more synchronized than predicted by rainfall and food supply.
It also does not account for all species, particularly the browsers or mixed feeders such as dikdik and oribi.
However, dikdik, the other synchronized species, is very much a "hider" species.