Owner Advantage in the fiddler crab, Uca mjoebergi. Are owners more motivated than floaters because they have invested in neighbour relations?

Resource owners generally win contests against intruders, a phenomenon referred to as the 'Owner Advantage' (OA). Uca mjoebergi is a typical fiddler crab that is highly sociable, territorial and lives in mixed sex colonies on intertidal mudflats. Burrows are used in territory defence, for mating, and as refuge from predators and environmental stresses. Fights are common between owners and floating males who battle for ownership of the territory and burrow.

Experiments were conducted from 28th Sept - 30 Dec 2006 at the lower reaches of Ludmilla Creek within East Point Reserve, 5km North of Darwin, NT. Previous experiments have revealed that owners win more contests than floaters because they are more motivated. This experiment was designed to test if owners are more motivated than floaters because they have invested more in neighbour relations.

The results indicate that the total amount of time a male has been present in a territory did not affect his fighting succes. The amount of time he spent on the surface or with his burrow open represented the time he could interact with neighbours, had a marginally significant influence on fighting success. Establishing relations with neighbours appear to convey at least a small increase in motivation leading to a weak fighting advantage.