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1 June 2010 Delayed Plumage Maturation Correlates with Testosterone Levels in Black Redstart Phoenicurus ochruros Males
Lucie Schwarzová, Roman Fuchs, Daniel Frynta
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Abstract

Black Redstart males usually have female-like (olive-brown) feathers during their first breeding season. This subadult coloration contrasts sharply with the grey and black feathers of the adults. To examine the proximate mechanisms of this phenomenon, known as delayed plumage maturation, we assessed levels of testosterone in circulating blood of subadult and adult males captured in Prague, Czech Republic. Analysis of 23 blood samples (performed by radioimmunoassay) collected during the molt, i.e., at the time of plumage development, revealed significantly higher testosterone levels in males molting to the adult color than in those molting to the subadult one. This may suggest a certain role played by testosterone in the regulation of delayed plumage maturation. However, there were no marked differences between males of different coloration and/or age during the breeding season. Analysis of 46 blood samples collected outside the molting period confirmed the seasonal testosterone pattern (spring peak and winter minimum) typical of most temperate passerines.

Lucie Schwarzová, Roman Fuchs, and Daniel Frynta "Delayed Plumage Maturation Correlates with Testosterone Levels in Black Redstart Phoenicurus ochruros Males," Acta Ornithologica 45(1), 91-97, (1 June 2010). https://doi.org/10.3161/000164510X516146
Received: 1 September 2009; Accepted: 1 March 2010; Published: 1 June 2010
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KEYWORDS
Black Redstart
delayed plumage maturation
Phoenicurus ochruros
testosterone
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