Common cuckoos (Cuculus canorus) lay eggs with larger yolk but not more testosterone than their great reed warbler (Acrocephalus arundinaceus) hosts

Research output: Contribution to journalArticle

24 Citations (Scopus)

Abstract

The relatively small common cuckoo Cuculus canorus hatchling evicts its host's propagules, then begs intensively to elicit sufficient parental care. The proximate mechanisms of these behaviours are still obscure. Recent intraspecific studies on avian broods revealed higher competitive ability of nestlings that hatched from eggs with a greater yolk testosterone level. Greater maternal investment in yolk steroids may provide an explanation for the vigour of parasitic chicks. Unexpectedly we found no evidence of higher yolk T concentration and absolute amount of T in cuckoo eggs compared to those of its host, the great reed warbler Acrocephalus arundinaceus. The yolk mass of cuckoo eggs, however, was significantly greater than that of the host, despite egg volumes being similar between these two species. Relatively larger yolks of cuckoo eggs indicates differential maternal investment strategies by parasites as more yolk may contain additional macronutrients to increase the vigour of parasitic young during the early days of its life and/or to enhance its begging display to elicit care from foster parents.

Original languageEnglish
Pages (from-to)271-277
Number of pages7
JournalEthology Ecology and Evolution
Volume16
Issue number3
DOIs
Publication statusPublished - Jan 1 2004

Keywords

  • Androgens
  • Bird egg
  • Brood parasitism
  • Maternal investment
  • Yolk testosterone

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Animal Science and Zoology

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