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Portrait of Henrik Smith. Photo.

Henrik Smith

Professor

Portrait of Henrik Smith. Photo.

Egg yolk androgen levels increase with breeding density in the European Starling, Sturnus vulgaris

Author

  • K M Pilz
  • Henrik Smith

Summary, in English

1. High breeding density can cause elevated plasma androgen levels in adult birds. Since maternal androgens are deposited into egg yolk, high breeding density may result in elevated yolk androgen levels as well. 2. The relationship between breeding density and yolk androgen levels was examined in the European Starling, Sturnus vulgaris. The concentration and total content of yolk androstenedione and yolk testosterone were measured in eggs from 24 clutches distributed across nine different colonies of nestboxes. 3. Yolk androstenedione and testosterone levels were significantly higher in colonies where a greater proportion of nestboxes had active nests. 4. Yolk testosterone levels were significantly higher, and yolk androstenedione levels were marginally higher, in colonies with a greater absolute number of active nests. 5. Yolk androgen levels were not related to the number of active nests in adjacent nestboxes. 6. We conclude that female starlings nesting in colonies with higher breeding densities transfer more androgen to their eggs. 7. This relationship may be mediated by increased interfemale aggression, particularly towards floater females searching for mates or nests to brood parasitize, in high-density colonies. Such a relationship between maternal environment and maternal yolk androgens may represent adaptive maternal modification of offspring phenotype or a non-adaptive physiological constraint which females cannot avoid.

Department/s

  • Biodiversity
  • Biodiversity and Conservation Science

Publishing year

2004

Language

English

Pages

58-66

Publication/Series

Functional Ecology

Volume

18

Issue

1

Document type

Journal article

Publisher

Wiley-Blackwell

Topic

  • Ecology

Status

Published

Research group

  • Biodiversity and Conservation Science

ISBN/ISSN/Other

  • ISSN: 1365-2435