Escape behaviour in shore crabs: constraints of body size and available shelter

The escape behaviour of organisms that retreat to shelter to avoid predators is influenced by availability and quality (e.g. appropriate size) of shelters. We examined escape behaviour (flight initiation distance, distance fled to shelter) of the crab Leptograpsus variegatus, relative to shelter size and distribution on a shoreline with multiple shelters and on a shoreline with limited shelter. Larger crabs tended to be nearer to larger shelters than smaller crabs and fled sooner and further than smaller crabs. Larger crabs often fled past the nearest shelters if they were too small. Group size increased at the site with fewer shelters, but this did not influence flight behaviour. We conclude that the availability of shelters and body size influences escape behaviour of these crabs.