Owner Advantage in the fiddler crab, Uca mjoebergi. Do owners win more contests than floaters because they are superior fighters?

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. This experiment was designed to determine if owner advantage in the fiddler crab Uca mjoebergi, was due to floaters being poorer fighters for their size compared with burrow owners. This was achieved by comparing the fights between owners - prior floaters, with the fights between owners - prior territory owners. In both cases owners won the majority of fights; winning 92.5% of the their fights against prior owners, and 90% of their fights against prior floaters. Therefore prior floaters do not appear to be poorer fighters.