Inter- and intra-sexual selection: the role of song in a lek mating system

Abstract

Bird song is generally thought to function in both mate attraction and territorial defence. In lek mating systems the importance of song in mate attraction appears clear but a possible intra-sexual role for song is not known. The role of song was studied in the lek mating system of the ochre-bellied flycatcher, Mionectes oleagineus (Aves, Tyrannidae). Song rates were significantly correlated with the rates at which females and other males visited a male's territory. A temporary muting experiment was conducted to determine the basis of this correlation. Experimentally muted males suffered far greater intrusion rates than did either control or sham-experimental males. Five of the six experimental males quickly lost their territories to intruding males. Two experimental males regained their territories upon regaining their ability to sing. In this species, song plays a key role in male-male interactions on leks, and is also used by females in assessing potential mates.