Meeting Abstract
The production of song for mate attraction can be costly. Thus, males should modulate its production according to its probable benefits. It is known that male birds increase song production based upon the proximity and reproductive competence of females. Further, males increase song production when exposed to high quality song of conspecific males. To date, the influence of other sexually-selected signals upon song production, such as plumage coloration, has not been investigated. House finches (Carpodacus mexicanus) are highly social and non-territorial, and females show a preference for both elaborate male song, and the intensity of red carotenoid-based plumage coloration. Therefore, it may be profitable for more colorful males to invest less in energetic song relative to less colorful birds, or vice versa. The social environment may also modify investment in song, for example less colorful males relative to their conspecifics may increase their song production to maximize their attractiveness to females. We tested these predictions with captive house finches by manipulating male plumage coloration through carotenoid supplementation during molt, so that 50% of birds had red plumage whereas the other 50% had yellow plumage. Males were then housed under 3 social environments, 1) all red, 2) all yellow or 3) a mixture of red/yellow birds. We then recorded male song after presentation of a female. To control for female attentiveness towards individual males, we also measured female behavior. Our results show that more colorful males invest more in song production regardless of their social environment. But when males are housed with more colorful conspecifics they invest more in song compared to those housed with equally un-colorful males. This study provides novel evidence that a male’s feather coloration, and his social environment influences investment in song.
