Male African elephants, Loxodonta africana, can distinguish oestrous status via urinary signals

Abstract

African elephants are a polygynous species that raise offspring in a matriarchal society. Unlike females, males disperse, spend time in male groups and search for mates when mature. Urinary chemical signals aid males in detecting reproductively active females. A preovulatory pheromone has been identified in Asian elephants, Elephas maximus, but has not yet been experimentally identified in African elephants. In this study, the goal was to determine whether adult captive male African elephants can distinguish between urine from conspecific females in luteal and periovulatory oestrous stages as an indication that a preovulatory pheromone is released in the urine. Urine was collected from seven different female African elephants during their luteal and periovulatory periods of oestrus. Bioassays were conducted with nine adult male elephants housed at six different facilities. Males were presented with the two urine types and a control sample once a day over 3 days to reduce sample novelty, which can result in misleadingly high responses. All males showed greater chemosensory responses to the periovulatory urine by trial 3 with the ability to distinguish the urines increasing over the 3 days. This is the first experimental behavioural evidence that African elephants release an oestrous pheromone in the urine. The ability of the captive male elephants to discern between the two urine types bolsters the hypothesis that there is a preovulatory pheromone in African elephants and encourages efforts to identify it.