Christy, from the Smithsonian Tropical Research Institute (STRI) in Panama, Julia Baum, an undergraduate at McGill University, and STRI researcher Pat Backwell thought that hoods might attract females because they look like objects that provide temporary hiding places. As reported recently in the journal Animal Behaviour (66: 89-94) they found ample support for this idea. They showed that female fiddler crabs, including species that do and do not build structures, are equally attracted to hoods and other objects to escape predation. They then replaced males' hoods with stones, shells, pieces of wood and hood replicas and tested their attractiveness to females. Females found all males to be equally attractive regardless of what kind of object was at their burrow. The researchers conclude that some male courtship signals may be designed to keep females safe as they search for a mate, not to advertise the quality of the signaler and more generally, that a species' ecology can favor responses that in turn become incorporated into courtship.
Ref: Christy, John H., Baum, Julia K., and Backwell, Patricia R. Y. 2003. "Attractiveness of sand hoods built by courting male fiddler crabs, Uca musica: test of a sensory trap hypothesis." Animal Behaviour 66(1): 89-94
The Smithsonian Tropical Research Institute, headquartered in Panama City, Panama, is one of the worldìs leading centers for research on the ecology, evolution and conservation of tropical organisms.