Male quality and conspecific scent preferences in the house finch, Carpodacus mexicanus

There is increasing evidence that birds use chemical cues in different contexts, and this is changing the traditional view that birds are the only largely olfaction-free vertebrates. We performed a choice experiment to examine whether male house finches exhibit any preferences for the sex of conspecifics when only their chemical cues are available. When exposed during the breeding season to the scent of a male and a female, males appeared to respond indiscriminately to both odours. However, when we analysed a posteriori the choices of males in relation to their relative quality, males with worse quality than scent donor males avoided the male-scented area, whereas males with better quality moved towards the male-scented area. Our results suggest that in the context of mate choice/competition for mates, house finches may obtain information via olfaction to assess the quality of rival males.