Female preference for long tails in lekking Jackson's widowbirds: experimental evidence

Abstract

Jackson's widowbird, Euplectes jacksoni, is a lek-breeding weaverbird (Ploceidae) of East African grassland. Each male displays on his own display court: a cleaned circular track around a grass tuft. The male performs a jump display that attracts females, and a ground display directed at visiting females. Breeding males are black with a tail 20 cm long, which is conspicuously exhibited during display. Females and non-breeding males are streaky brown with a short tail. Tail length was the single most important predictor of male mating success in a previous study, suggesting that the tail is a cue for female mate choice. In the present experiment, males with shortened tails received fewer visits by females than control males, in 11 of 13 test pairs of neighbouring males. The rate of visits by females was correlated with male copulatory success. Display rate and lek attendance were not affected by tail manipulations. The results suggest that female Jackson's widowbirds prefer males with long tails. The experimentally produced difference in tail length roughly spans the standard deviation of a large sample of displaying males. This implies that cue assessment by females is accurate enough to impose sexual selection on male tail length. A previously found positive relationship between tail length and an index of body condition was strengthened by the increased sample size. The results are discussed in relation to current sexual selection theory.