ABSTRACT
The signal function of ornamental traits has become a focus of intense interest by behavioral and evolutionary biologists. Ornamental traits posed among the greatest challenges to Darwin's theory of natural selection (Cronin 1991) because they seemed to decrease survival while not directly enhancing fecundity. Darwin solved this problem by devising his theory of sexual selection whereby traits like ornamental coloration evolved because they enhanced access to mates through mate attraction or success in intrasexual competition (Darwin, 1871). Darwin proposed that female mate preference was primarily responsible for the evolution and maintenance of ornamental coloration in birds. While Darwin (1871) correctly solved the primary dilemma of how ornamental coloration evolved, he left many questions unanswered including what ornamental traits signal to conspecifics.
