Mudballing revisited: Further investigations into the construction behaviour of male Uca tangeri

Male and female Uca tangeri (the only ddler crab species to inhabit Europe) construct mudballs from mud excavated from within their burrows. Individual males placed similar patterns of mudballs each low tide, suggesting that there is some degree of stereotypy. When mudballs were experimentally moved further from the burrow or closer to it, males only repositioned those that were moved closer, placing them further away again. However, males did not replace mudballs that had been experimentally destroyed at the end of the mudballing phase when they had started to court females. In binary presentation tests, females showed no signi cant differences in response to mudballs made from different types of mud, or different numbers of mudballs. These results are consistent with earlier ndings that male mudballs function as territory boundaries. However, we provide evidence that male mudballs have no function in female attraction, contrasting with previous studies