When is waving performed in the ocypodid crab Scopimera globosa?

Abstract

Waving displays of the intertidal ocypodid crab Scopimera globosa were observed in the field in relation to other behaviors. Most of the crabs observed to wave were males holding burrows. The proportion of waving crabs was higher in the summer months when ovigerous females and precopulatory behavior (males chasing females) occurred. A negative correlation between waving and precopulatory behavior was found i.e., males performing waving intensively exhibited less frequent precopulatory behavior. However in more than half of the precopulatory behaviors, waving occurred both immediately before and after precopulatory behavior. No correlation was found between the waving frequency and either the frequency of aggressive encounters or the density of neighboring crabs. Immediately before and after an aggressive encounter, the case when waving occurred was observed at a similar frequency to the case when no-waving occurred. These observations suggest that waving in S. globosa functions as a courtship behavior advertising burrowholding males.