The social implications of traditional use of lek sites in the ruff Philomachus pugnax

Abstract

In almost every lekking vertebrate, adult males use traditional lek sites. This paper attempts to explain this phenomenon by investigating the social implications of traditional use of lek sites. A population of ruffs Philomachus pugnax was observed during six breeding seasons, and lek stability, site fidelity, male copulatory success, and male dominance relationships were studied. Ninety percent of the territorial males were site-faithful within and between years, and male dominance, copulatory success, and order of territory establishment were all inter-correlated. Males that were relatively dominant and successful as first-year territorials were more likely to return to the area, established themselves even earlier in their second year, and rose in success rank. The frequency of disrupted copulations was very low, despite the tightly clustered territories on leks. This suggests that well-developed dominance relationships exist between males. Site-faithful males are more likely to acquire accurate information about the competitive abilities of other males, and such information is probably necessary for stable dominance relationships to develop. Such relationships reduce the intensity of male aggression, thereby reducing the risk of male injury. High levels of male aggression also deter females. Furthermore, stable dominance relationships enables low-/and medium-ranked males to remain on the leks while waiting for the top males to drop out. The high site-fidelity of lekking males, thus, is suggested to have evolved to facilitate the establishment of stable dominance relationships, which are beneficial to all territorial males, irrespective of rank.