Female calls in lek-mating birds: indirect mate choice, female competition for mates, or direct mate choice?

I tested predictions from ultimate hypotheses of why female great snipe Gallinago media give loud calls when visiting leks, using observational data and playback experiments. One hypothesis is that calls might be used in female--female competition for popular males, either (1) in an aggressive context toward a specific female, or (2) toward females in general to defend the male. It has also been suggested that female calls (3) may not have an adaptive function, the capability of vocalizing being explained as a correlated response to selection on male singing. Further, calls might function as (4) a copulation solicitation toward a specific male. Finally, calls might have a function in mate choice, either (5) in indirect mate choice as a fertility advertisement to incite male fighting, or (6) in direct mate choice as a mate-sampling aid to provoke quality-revealing responses from males. Disproportionately many female calls were uttered when no other females were present on a male's territory and in territories of males without mating success, contradicting hypotheses 1 and 2. Female calls were not associated with copulation; calls generally occurred several days before copulations, contradicting hypotheses 4 and 5. Playback of female calls attracted males and increased fighting among males, even if females were present nearby, contradicting hypothesis 3. Males changed their own songs in response to playback, and the response was related to their mating success. Taken together, the results are only consistent with one of the hypotheses considered--female calls may function as a mate-sampling aid used in direct mate choice. Copyright 2002.