Golden Whistler Pachycephala pectoralis
The golden whistler is a highly ornamented small passerine inhabiting Australian forests. Male golden whistlers display several plumage ornaments, including black, yellow and white plumage and are also very vocal, with large song repertoires. We were interested in the evolutionary ecology of these signals.
Display signals in male golden whistlers include an unpigmented white throat patch, a carotenoid-based yellow breast and nape band, and a melanin-based black chin-stripe. We assessed the relative importance of these plumage patches as agonistic signals, and found that only the throat patch was correlated with contest-related attributes. Males with large throat patches defended larger territories and commenced breeding earlier. In a second study, we examined the response of territorial pairs to both the static plumage signal (throat patch) and a dynamic signal (song) during territorial disputes. Males paid attention to both plumage and song signals, while females only responded to song. Males also responded faster to other males with throat patches similar in size to their own, suggesting that they may assess relative throat patch size before engaging in aggressive encounters.
Finally, we explored the factors that affected male genetic reproductive success in golden whistlers. We didn’t find any relationship between extra-pair mating success and genetic factors, territory size, male age or incubation effort. However, males with yellower breast plumage and larger song repertoires had higher reproductive success. Interestingly, the opportunity for extra pair mating appeared to be negatively affected by local breeding synchrony.
The research described above formed part of a PhD carried out by Dr. Wouter Van Dongen entitled “Evolutionary ecology of multiple ornaments in the golden whistler”. Wouter currently holds a post-doctoral research position at the Konrad Lorenz Institute of Ethology, Vienna, Austria. He is researching the behavioural genetics of coloniality in birds and fish.
More information about this research can be found in these publications:
van Dongen, WFD & Mulder, RA (2009). Multiple ornamentation, female breeding synchrony and extra-pair mating success of golden whistlers (Pachycephala pectoralis). Journal of Ornithology 150: 607-620. Full text
van Dongen, WFD & Mulder, RA (2008). Male and female golden whistlers respond differently to static and dynamic signals of male intruders. Behavioral Ecology 19: 1025-1033. Full text
van Dongen, WF & Mulder, RA (2007). Relative importance of multiple plumage ornaments as status signals in golden whistlers (Pachycephela pectoralis). Behavioural Ecology & Sociobiology 62: 77-86. Full text
van Dongen, WF & Mulder, RA (2005). Isolation and characterisation of microsatellite markers for paternity assessment in the golden whistler (Pachycephela pectoralis: Aves). Molecular Ecology Notes 5: 4-6. Full text
Photo: David Kleinert