The manipulation of food resources reveals sex-specific trade-offs between parental self-feeding and offspring care

S. Markman, B. Pinshow, J. Wright

Research output: Contribution to journalArticlepeer-review

28 Scopus citations

Abstract

Parent Palestine sunbirds (Nectarinia osea) feed on flower nectar that is not fed to their nestlings. This phenomenon provided a unique opportunity to manipulate self-feeding rates of parent birds independently of the rate at which they feed arthropod prey to their offspring. Based on provisioning models, we predicted that parents would invest more in their young as the energy content of their own food increased. From our earlier work, we also predicted that the levels of sex-specific activities of males and females would differ as the energy content of their food increased. Sunbird pairs with two or three nestlings were provided with feeders containing a low-, medium- or high-concentration sucrose solution. As the sugar concentration increased, the females delivered arthropods at a greater rate to their nestlings, removed proportionally more faecal sacs and spent longer at the nest, while the males increased their mobbing effort. Nestling food intake and body mass, but not tarsus length or bill size, were larger in small broods than in large broods, and increased with increasing feeder sugar concentration. These results imply that increasing the energy content of food consumed by parent sunbirds allows them to increase the rate at which other foods are delivered to their young and to increase other parental care activities as well. The results also add credence to the idea that behavioural decisions reflect life-history trade-offs between parental self-feeding and investment in current young.

Original languageEnglish
Pages (from-to)1931-1938
Number of pages8
JournalProceedings of the Royal Society B: Biological Sciences
Volume269
Issue number1503
DOIs
StatePublished - 22 Sep 2002

Keywords

  • Cost of reproduction
  • Life history
  • Mobbing
  • Nestling feeding
  • Parental care
  • Sunbirds

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