Access

You are not currently logged in.

Access your personal account or get JSTOR access through your library or other institution:

login

Log in to your personal account or through your institution.

If You Use a Screen Reader

This content is available through Read Online (Free) program, which relies on page scans. Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.

Environmental Variability, Life-History Covariation and Cohort Effects in the Red-Billed Chough Pyrrhocorax pyrrhocorax

J. M. Reid, E. M. Bignal, S. Bignal, D. I. McCracken and P. Monaghan
Journal of Animal Ecology
Vol. 72, No. 1 (Jan., 2003), pp. 36-46
Stable URL: http://www.jstor.org/stable/3505541
Page Count: 11
  • Read Online (Free)
  • Download ($18.00)
  • Subscribe ($19.50)
  • Cite this Item
Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Environmental Variability, Life-History Covariation and Cohort Effects in the Red-Billed Chough Pyrrhocorax pyrrhocorax
Preview not available

Abstract

1. The consequences of environmental variability for life-history evolution are predicted to depend on the pattern of covariation amongst life-history traits. Using data from a 20-year study of individually marked red-billed choughs, we investigate the short- and long-term life-history consequences of population-wide variation in reproductive conditions, and demonstrate clear among-cohort variation and covariation in life-history parameters. 2. The mean number of offspring fledging per breeding event varied among years, and was correlated with environmental conditions (temperature and rainfall) during the months preceding breeding. As the variance in breeding performance did not differ among years and choughs did not miss breeding seasons, variation in environmental conditions affected the whole breeding population. Thus the quality of the chough's breeding environment varied amongst years. 3. Juvenile survival, the probability of recruitment to the breeding population and breeding longevity varied amongst cohorts, and these were positively correlated with the quality of the cohort's natal environment. Offspring fledging under good conditions were more likely to survive to breeding age and recruit, and had longer breeding lives than offspring fledging under poor conditions. 4. Age at first breeding varied amongst cohorts, and increased with population size at maturity rather than natal conditions. 5. The total number of offspring that recruits ultimately fledged varied primarily with breeding longevity rather than recruitment age. Thus, the consistent positive covariation amongst life-history traits meant that the total number of offspring fledged by recruits during their breeding life varied amongst cohorts, and was correlated with the quality of a cohort's natal conditions. Choughs fledging under good conditions themselves ultimately fledged more offspring. 6. Such environmentally determined variation in offspring fitness is expected to influence optimal patterns of parental investment. We discuss the predictions that environmental variability should select for investment in adult survival and for reduced reproductive effort in poor years.

Page Thumbnails

  • Thumbnail: Page 
[36]
    [36]
  • Thumbnail: Page 
37
    37
  • Thumbnail: Page 
38
    38
  • Thumbnail: Page 
39
    39
  • Thumbnail: Page 
40
    40
  • Thumbnail: Page 
41
    41
  • Thumbnail: Page 
42
    42
  • Thumbnail: Page 
43
    43
  • Thumbnail: Page 
44
    44
  • Thumbnail: Page 
45
    45
  • Thumbnail: Page 
46
    46