The colouration of the males allows them to visibly stand out from the brown forest floor. This bright colouration provides a sexual advantage for the adult males, increasing their likelihood of successfully mating. The result is rapid evolutionary selection within the species for brighter plumage and more conspicuous behaviour patterns in the males. The bright colouration also makes the males more susceptible to predation. Males are more expendable for this reason; only a small number of males are needed within any generation in order to perpetuate the species. While sexual selection leads to bright plumage, natural selection in turn favors defensive colouration in the birds. There is higher fitness in birds monitoring nests whose colouration acts as camouflage-protection from predation.