Sexual dimorphism in house sparrow eggs

P. J. Cordero*, S. C. Griffith, J. M. Aparicio, D. T. Parkin

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

96 Citations (Scopus)


Recent evidence has revealed an apparently high degree of control by female birds over the physiological aspects of their reproduction and offspring sex allocation, consistent with adaptive hypotheses of sex allocation and differential investment in their offspring. In the house sparrow, we investigated possible mechanisms that may be used by females to enhance the fitness returns from a reproductive effort. Using molecular techniques, we demonstrate that house sparrow eggs containing male embryos are significantly larger than those containing female embryos. We also found that male embryos were laid randomly with respect to laying order. We speculate that this sexual dimorphism of eggs is adaptive, because male house sparrows show greater variance in condition-dependent reproductive success than females. More important, the result provides further evidence of the ability of females to detect or control ovulation of either male or female ova and to differentially invest in one sex over the other.

Original languageEnglish
Pages (from-to)353-357
Number of pages5
JournalBehavioral Ecology and Sociobiology
Issue number5
Publication statusPublished - 2000
Externally publishedYes


  • Egg size
  • Parental investment
  • Passer domesticus
  • Sex ratio


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