Another possibility, she adds, is that females avoid males they’ve already mated with. This could be a female strategy to mate with many males so that no male knows for sure whether a calf is his—a theory that Sayigh says is also strong. This could help protect calves from being harmed as infanticide is a documented behavior in male dolphins.
For Mann, it’s not necessarily surprising that females would avoid specific males, especially when they are likely to be cycling. Previous research has shown that female dolphins in Shark Bay avoid adult males generally when more than one male is present, which is when they tend to be more aggressive, she says.
“What is unique is showing that females are responding to specific male signature whistles,” she adds.
Sayigh agrees. “The fact that they use their knowledge of signature whistles and of the individuals that are linked to those signature whistles to guide socially informed decisions is a really important contribution,” she says.
There is still more to uncover about their relationships and choices during mating, and the mechanism underlying how females are making this choice to avoid males, whether it’s associating a male’s whistle with past experiences, recognizing specific males and remembering their behavioral history, or learning about males by observing how they treat other females.