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Lekking in the ocre-bellied flycatcher, Mionectes oleagineus

University of British Columbia

In this thesis, I examine the social and ecological pressures that have resulted in the evolution and maintenance of lekking in the ochre-bellied flycatcher, Mionectes oleagineus. I do this by asking two general questions: i) where should leks occur, and ii) how many males should settle at a site. I begin by considering the influence of female distributions on male settlement patterns. The “hotspot” hypothesis suggests that population level patterns of female movement and/or dispersion determine male settlement patterns. Leks occur due to marked heterogeneities in these distributions. I confirmed three novel, interspecific predictions of the hotspot hypothesis: 1) leks of ecologically similar, sympatric species are clustered; 2) the degree of clustering is related to the degree of similarity in diet between the species; and, 3) species with similar diets show correlated changes in the sizes of neighbouring leks. If, as suggested by this interspecific comparison, hotspot mechanisms are involved in lek evolution, then leks should be associated with some aspect of female distribution. Using radio-telemetry I found that females use identifiable and discrete routes when travelling through their environment. Lek location was strongly associated with these routes and tended to be associated with areas where the most females could be encountered. I also examined the consequences of variation in lek size. Females visited and mated at both leks and solitary territories. While female visitation rates increased with lek size, they did so in proportion to the number of males present. Thus not only did females not show a preference for larger leks, but there were no identifiable benefits to males of display at larger leks. There was, however, a cost. At leks, 28% of displays to females were interrupted by intruders, such interruption did not occur at solitary display sites. These results contradict the predictions of “preference t’hypotheses and at least one version of the hotshot hypothesis. Finally, I investigated the hypothesis that males attempt to limit lek size due to the costs associated with display at larger leks. This was confirmed in a playback experiment. This experiment also demonstrated that males can distinguish neighbours from strangers using song.

Thesis/Dissertation

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2009-04-22

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http://hdl.handle.net/2429/7460

Zoology

University of British Columbia

UBCV

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