Do female animals flirt, or is it just males?

Chris Smith put this question to behavioural ecologist Sophie Mowles...

Sophie - A lot of this relies on parental care and it’s down to the way in which male and female animals create their gametes, so they’re sex cells, eggs, sperm. From the very start, a female animal has to invest a lot. They have to create a really nutritious egg from which the offspring will develop. Sperm is cheap; they’re small and they’re really easy to make so males can mate with multiple females, but for every female, that fertilisation is a real major decision. They’ve got to raise that offspring from scratch so, for the most part, they need to be really really sure that the male that they’re mating with is good quality. The peacock has to prove his genetic quality to the female and she can make her choice. The stag has to fight and win that harem of females.

There are some situations where the females care less about the offspring and the males provide more care. In those situations we can get what’s called “sex role reversal,” where the male is providing the care and they have to choose the female. In these cases, females have even evolved to be more colourful to advertise that they are worth investing in. There are some birds that do this, like gokarnas, which are a bird that creates a nest on water. It’s a floating nest and you can only fit four eggs in that otherwise it will sink or they’ll fall out. From a female’s perspective, the only way to have more offspring than four is to find another male, so she needs to have a mate, put him on a nest, and then move on an convince another male that she’s worth investing in. You see this in some cold weather birds. There’s an arctic wader such as phalaropes where you can’t have any more eggs because they’ll get cold.

But famously, we see this in seahorses and pipefish because the male carries the eggs so he has to be absolutely sure that she’s worth bearing those offspring with and, in those cases, the females have to advertise their good qualities. They often have the colours and they display these to the males in complex dances so that he knows yes, you’ve got good genes and they’re going to be good offspring and yes, I will look after them for you.