Female nest dispersion and breeding biology of the polygynous red-collared widowbirds (Euplectes ardens)

摘要

We explored characteristics and patterns of nest distribution, and their putative costs and benefits to breeding females, in polygynous Red-collared Widowbirds (Euplectes ardens). Red-collared Widowbirds differ from most other Euplectes species, in that male nestbuilding is reduced to simple nest-rings used in courtship; females alone position and build nests in the territories. Females used only 37% of available territory area for nesting and aggregated at the centers of territories, possibly to take advantage of male vigilance from prominent central perches or to avoid harassment by neighbors. However, irrespective of territory size or number of females on the territory, females maintained relatively even spacing, with nests 15 m apart. Nest predation rates were higher (28.2% day−1) during the nestling period than during incubation (14.6%), but independent of the number of actively nesting females on a territory. During synchronous nestling stages, however, birds nesting close to other birds incurred higher predation costs. Females may, therefore, centrally clump their nests on a territory but maintain enough distance between nests to reduce nest predation. Females choosing unmated males (monogamous) received no greater costs or benefits than females settling with mated males (polygynous). Taken with our earlier finding of strong female preference for longertailed males (Pryke et al. 2001a), our results here suggest that females may gain indirect genetic benefits of higher-quality offspring without incurring the high costs of sharing territories.