Intersexual spatial relationships in a lekking species: Blue-crowned manakins and female hot spots

Abstract

Leks offer an intriguing evolutionary problem: why do males aggregate when this apparently leads to fitness costs? Aggregation costs can be balanced if males settle on patches where they are more likely to encounter females (hot-spot hypothesis). We evaluated whether female hot spots can account for patterns of lek structure in the blue-crowned manakin (Lepidothrix coronata) by modeling female distribution patterns relative to lek locations in two 100-ha plots. Individual females were mapped based on nest locations and capture points and had their home ranges (HRs) modeled based on radiotelemetry data. The number of females that lekking males can be expected to encounter was estimated as the number of individual female HRs overlapping each male territory; hot spots were defined as patches where more females are found than average. We investigated how changes in female HR size and devaluation effects (decrease in female availability due to the presence of neighboring males) influence male access to females. Both factors strongly influenced the expected rates of female encounter, but the hot-spot hypothesis was not supported: most male territories consistently overlapped fewer or just as many female HRs as expected by chance. Leks were not closer to hot spots than similar-sized nonlek sites. A proportion of males were, indeed, settled at hot spots, but, contrary to predictions of the hot-spot hypothesis, they belonged to smaller leks than males located outside hot spots. Our results indicate that this lack of spatial correlation between males and females results partly from differences in sex-specific habitat preferences. © The Author 2007. Published by Oxford University Press on behalf of the International Society for Behavioral Ecology. All rights reserved.