Synchronous parturition of Procavia capensis and Heterohyrax brucei during drought in Zimbabwe

The demographics of syntopic populations of Procavia capensis (rock hyrax) and Heterohyrax brucei (yellowspotted hyrax) were studied during a drought from October 1991 to May 1992 in the Matobo National Park (MNP), Zimbabwe. Pups comprised >27% of the samples after a synchronous March April 1992 birth event in which about 50% of the adult females participated. The timing and frequency of parturition in the two species are in response to a unimodal temporal distribution of rainfall with a historical peak from December to January. Births coincided with a heavy March rainfall after and before extended periods without rain. Litter size seemed little affected by the drought. Sixteen of 19 nurseries were communal, and six (37,5%) of these, heterospecific. Reproductive individuals may conserve energy as the effectiveness of vigilance increases with group size, especially for heterospecific groups. Extreme predation pressure in the MNP may be a selective agent favouring synchronous parturition and cooperative behaviour by the two species of hyrax.