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Costly steroids: egg testosterone modulates nestling metabolic rate in the zebra finch

  • Michael Tobler
  • Jan-Åke Nilsson
  • Johan Nilsson
Publishing year: 2007
Language: English
Pages: 408-410
Publication/Series: Biology letters
Volume: 3
Issue: 4
Document type: Journal article
Publisher: Royal Society

Abstract english

The transfer of non-genetic resources from mother to the offspring often has considerable consequences for offspring performance. In birds, maternally derived hormones are known to influence a variety of morphological, physiological and behavioural traits in the chick. So far, the range of these hormonal effects involves benefits in terms of enhanced growth and competitive ability as well as costs in terms of immunosuppression. However, since yolk hormones can enhance growth and begging activity, high levels of these hormones may also involve energetic costs. Here, we show experimentally that elevated levels of prenatal testosterone increase resting metabolic rate in nestling zebra finches (Taeniopygia guttata). Surprisingly, however, elevation of prenatal testosterone did not result in higher growth rates and, thus, differences in resting metabolism do not seem to be linked to nestling growth. We conclude that apart from immunosuppressive effects, high levels of egg steroids may also entail costs in terms of increased energy expenditure.


  • Biological Sciences
  • maternal hormones
  • testosterone
  • Taeniopygia guttata
  • metabolism
  • maternal effects


  • ISSN: 1744-9561