Male display areas in exploded leks: the importance of food resources for male mating success

The distinction between true lekking and resource-defense mating systems is difficult in exploded-lekking species, where resources in male territories may influence female choice. Here, we propose the use of path analysis as a way to establish the relative importance of phenotypic characteristics versus food resources on mating success and hence decide whether a population is closer to one or the other extreme of an exploded lek-resource-defense continuum. Using great bustards Otis tarda as model species, we first performed logistic regression analyses of potential predictors of display sites in three leks. Males selected sites with high visibility, close to resources, and exposed to females. Second, we examined through path analysis how the mating success of radiotagged males was affected by resources, females and competitors, compared with age and weight, the major phenotypic correlates of mating success. The direct effects of age and weight were much higher than their indirect effects via resources or females. This suggests that female choice based on male characters is the most important sexual selection mechanism during mating and supports defining the great bustard mating system as a true exploded lek. However, half of the males showed a variable degree of resource defense toward intruders, indicating that both mating tactics, exploded lekking and resource defense, occur together in the same population. We suggest that individual variability in the use of resource defense might exist in many other exploded-lekking species, increasing the difficulties found in fitting their mating behavior to accepted definitions of alternative mating tactics. [Behav Ecol]