Fidelity to Bowers, Adult Plumage Acquisition, Longevity and Survival in Male Golden Bowerbirds Prionodura newtoniana

Abstract

Male Golden Bowerbirds Prionodura newtoniana were studied over 20 consecutive seasons in rainforest on Paluma Range, north Queensland. Of 25 traditional (attended > 2 years) bower sites, involving 51 bower structures, 84% were attended every season. Mean minimum use of a traditional bower structure (built at traditional sites, as opposed to at rudimentary ones lacking long-term owners and only temporarily attended) was 9.6 years, at a mean of two per bower site over the study. Replacement bowers averaged 14 m from the replaced one. At five bower sites the same structure persisted for > 20 years. Nineteen of 25 sites were regularly attended every season by traditional owners; the remaining six had such owners during some seasons but during others were attended irregularly by immatures. Traditional bower owners occupied a site for an average of seven seasons; 17% attending for > 10 consecutive seasons, 40% for 7-10, 26% for 4-6 and 17% for < 4 seasons. An adult male never occupied more than one traditional bower site, simultaneously or consecutively. Only one to three traditional bower owners were replaced annually in climatically typical years whereas seven were replaced during a drought year. Eighteen males took over a traditional site in adult plumage (seven in their first year of this plumage, two in their second, and unknown for nine). Twenty immatures were first captured and marked at an average 300 m from the bower site they subsequently occupied. Six males took over a site in immature plumage and retained it as bower owner for one (n = 3), two, three and four seasons before acquiring adult plumage. Males (n = 45) were studied in adult plumage for at least seven years. One male was immature-plumaged for at least six years before attaining adult plumage. Another was adult-plumaged for > 14 years. Mean male annual survival rate (n = 48) was 91%, indicating a mean expectancy of further life after initial capture of 10.9 years. Three males were 19 (n = 2) or 20 years old by the end of the study, having owned traditional sites for 14, 15 and 16 seasons.