Previous studies have shown that a female dunnock Prunella modularis
increases her reproductive success on average by copulating with more than
one male resident on her territory and thereby obtaining extra help in
raising offspring. Here we document behavior by females that affects
which males copulate with them.
We found that, during her period of receptivity to copulation, a female in
a territory shared by two males often left the dominant (or alpha) male,
which guarded her most of the time, and approached the subordinate (or
beta) male when he sang.
A female's responses to individual males thus tends to increase her own
reproductive success by increasing her chances for copulation with both
males sharing her territory. Playbacks of tape-recorded songs in the
field showed that females approached only songs of resident males, not
Females can therefore discriminate individual males by their songs alone,
a capability not previously established for female songbirds. Despite
intensive guarding of females by males, mating success among male dunnocks
depends in part on female choice.