MATE RETENTION, HARASSMENT, AND THE EVOLUTION OF UNGULATE LEKS

Current models of lek breeding mostly suggest that males defend clustered mating territories because females show a preference for mating on leks. Here we argue that, in lek-breeding ungulates, males may also gain benefits from holding clustered mating territories because clusters retain does in estrus. We show that in fallow deer (Dama dama) harems are commonly disrupted by young males. Bucks that hold territories on the lek that lose their harems quickly regain does as other harems are disrupted, whereas bucks defending isolated, single territories rarely regain does the same day. The risk of harassment may also help to explain why does in estrus leave the large, unstable herds that they usually live in. Does in estrus are frequently chased by young males when outside male mating territories. Benefits of moving to the lek (versus moving to single territories) include reduced risks of long chases. Though intrusions by young bucks are the commonest cause of does leaving male territories in our study population, other factors that cause does to move between neighboring harems (including disturbance by predators and persistent courtship by males) may generate benefits to males holding clustered mating territories. Once clustered mating territories have developed, the additional costs of mate choice are likely to be low, and female preferences for particular male characteristics may be likely to develop.