Female crabs behave like they are mate-searching in order to reduce predation risk

What is it about?

Females that visit and reject several males are thought to be active mate searchers. We caught female fiddler crabs either at their burrows (terrirory holding) or moving across their mudflat habitat visiting and rejecting males (wandering). When we displaced them to patches full of courting males, they behaved identically and all visited males and inspected the males' burrows. When we used a robotic crab to test the mate preferences of the territory holding and wandering females, both types approached the same faux males. When we 'swooped' a plastic bird over both types of females whilst they were moving across the mudflat, we found that they returned to the burrow of the male they last visited. Taken together, in this species, females visit and reject males when they are displaced from their burrows, regardless of whether they are looking for a mate or a burrow. They do this so that they can easily retreat to a nearby burrow so that they can easily retreat from predators.

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Why is it important?

Here, we see females behaving like mate-searchers when really they looking for a burrow. This suggests that the classic definition of active mate searching- where females visit and reject several males before choosing one- may need to be considered more carefully when males hold resources that directly benefit females.