Plumage coloration and social context influence male investment in song

Abstract

Animals use multiple signals to attract mates, including elaborate song, brightly coloured ornaments and physical displays. Female birds often prefer both elaborate male song and intense carotenoid-based plumage coloration. This could lead less visually ornamented males to increase song production to maximize their attractiveness to females. We tested this possibility in the highly social and non-territorial house finch (), in which females discriminate among males based on both song and on the intensity of red carotenoid-based plumage coloration. We manipulated male plumage coloration through carotenoid supplementation during moult, so that males were either red or yellow. Males were then housed under three social environments: (i) all red birds, (ii) all yellow birds or (iii) a mixture of red/yellow birds. We recorded song after presentation of a female. Red males produced more song than yellow males. But when yellow males were housed with red conspecifics, they produced more song relative to yellow males housed with equally unattractive yellow males. This study provides novel evidence that a male's plumage coloration and the plumage colour of his social competitors influence investment in song.

The effect of social environment on bird song: listener-specific expression of a sexual signal

“…Songs may also be modified by effects from the external environment, such as territory quality ( Hoi-Leitner et al 1995 ; Zsebők et al 2017 ), predation risk ( Schmidt and Belinsky 2013 ), temperature ( Strauß et al 2020 ), and it can also depict seasonal variation within an individual ( Lattin and Ritchison 2009 ). As song is used as a signal for conspecifics, social environment may also be an important factor that mediates within-individual variation in song ( Geberzahn and Aubin 2014 ; Gersick and White 2018 ; Henderson et al 2018 ). For example, singers can emit different songs toward males and females in many species ( Kroodsma et al 1989 ; Kipper et al 2015 ; Ronald et al 2015 ), but song performance can also depend on the contextual circumstances, such as on the presence of other birds when singing to a female ( Vignal et al 2004 ; Gersick and White 2018 ).…”