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Portrait of Henrik Smith. Photo.

Henrik Smith

Professor

Portrait of Henrik Smith. Photo.

Effect of experimentally altered brood size on frequency and timing of second clutches in the great tit

Author

  • Henrik G. Smith
  • Hans Källander
  • Jan-Åke Nilsson

Summary, in English

Brood size in the Great Tit (Parus major) was manipulated (increased, decreased, or unchanged) when nestlings were 5 days old. Both the frequency of second clutches and the interbrood interval were affected. The number of nestlings and hatching date, but not nestling and female mass, differed between first broods followed and not followed by second clutches. Hatching date and the number of nestlings in the first brood explained most of the variation in interbrood interval, whereas female mass did not contribute. Feeding first-brood nestlings and fledglings is an energy-demanding process, and the female may have to allocate resources to brood-feeding at the expense of reproductive de- velopment. Furthermore, a larger brood requires a longer period of feeding than a smaller brood. These circumstances probably explain why the size of the first brood affects the timing of the second clutch. Female condition and food depletion of the territory do not seem to be important. Because late second clutches have a lower probability of fledgling survival than do earlier ones-and consequently are of lower value from the female's standpoint-a large first clutch may delay laying to the point that a second clutch is not worthwhile. We conclude that a female's decision whether to lay a second clutch is a strategic one based on the value of the second clutch; a female that "decides" to lay a second clutch starts as quickly as possible.

Department/s

  • Centre for Environmental and Climate Science (CEC)
  • Biodiversity
  • Evolutionary ecology
  • Biodiversity and Conservation Science
  • Life History and Functional Ecology

Publishing year

1987

Language

English

Pages

700-706

Publication/Series

Auk

Volume

104

Document type

Journal article

Publisher

Oxford University Press

Topic

  • Ecology
  • Zoology

Status

Published

Research group

  • Biodiversity and Conservation Science
  • Life History and Functional Ecology

ISBN/ISSN/Other

  • ISSN: 0004-8038