Lek size variation and its consequences in the ochre-bellied flycatcher, Mionectes oleagineus

Abstract

Several hypotheses suggest that the costs and benefits of display in aggregations of different sizes play a major role in both the evolution of leks and in the distribution of males across leks of different sizes. We examined the consequences of variation in lek size for both males and females in a study of the ochre-bellied flycatcher, Mionectes oleagineus. We observed 41 solitary display sites and leks, ranging in size from 1 to 5 males, over 3 breeding seasons. Although mean visitation rate by females was positively correlated with lek size, female visitation rate per male remained constant across lek sizes. The rate at which females visited the male who had the highest female visitation rate at each lek was positively correlated with lek size as predicted by the hotshot hypothesis. Neither mean nor per capita intrusion rates were correlated with lek size. For the top-ranked male, however, there was a significant correlation between intrusion rates and the size of the lek at which he displayed. Intrusion at leks may be costly, as 28% of female visits were interrupted by intruders. Solitary males suffered no such interference. Females show no preferences for larger leks, visiting and mating at solitary sites as well as at leks. However, females preferentially visit males with high singing rates, and this male trait may determine visitation patterns. Our data argue that preferences for larger leks are not important in the evolution of lekking in this species, nor do they affect lek size. Instead, the data are in accordance with the predictions of both the hotshot and hot-spot models. These processes may be operating simultaneously in this species.