The role of photoperiodism in the seasonal breeding of tropical African ungulates



Records of ungulate calving peaks, from different latitudes within the African tropics, are reviewed. Converting these peaks to conception dates, and plotting them against latitude, reveals whether the initiation of conception may be connected with a photoperiodic response. The north-south plots of a short-day species should lie in diagonally-opposed quadrants, and those of long-day species in the opposite quadrants. The analysis suggests that a photoperiodic stimulus could be a factor initiating conception in some species, but others lack any apparent relationship.