Decomposing the seasonal fitness decline

A1 Journal article (refereed)


Internal Authors/Editors


Publication Details

List of Authors: Öberg M, Pärt T, Arlt D, Laugen AT, Low M
Publisher: SPRINGER
Publication year: 2014
Journal: Oecologia
Journal acronym: OECOLOGIA
Volume number: 174
Issue number: 1
Start page: 139
End page: 150
Number of pages: 12
ISSN: 0029-8549
eISSN: 1432-1939


Abstract

Seasonal fitness declines are common, but the relative contribution of different reproductive components to the seasonal change in the production of reproductive young, and the component-specific drivers of this change is generally poorly known. We used long-term data (17 years) on breeding time (i.e. date of first egg laid) in northern wheatears (Oenanthe oenanthe) to investigate seasonal reproductive patterns and estimate the relative contributions of reproductive components to the overall decline in reproduction, while accounting for factors potentially linked to seasonal declines, i.e. individual and habitat quality. All reproductive components-nest success (reflecting nest predation rate), clutch size, fledging success and recruitment success-showed a clear decline with breeding time whereas subsequent adult survival did not. A non-linear increase in nest predation rate caused nest success to decline rapidly early in the season and level off at similar to 80 % success late in the breeding season. The combined seasonal decline in all reproductive components caused the mean production of recruits per nest to drop from around 0.7-0.2; with the relative contribution greatest for recruitment success which accounted for similar to 50 % of the decline. Our data suggest that changing environmental conditions together with effects of nest predation have strong effects on the seasonal decline in fitness. Our demonstration of the combined effects of all reproductive components and their relative contribution shows that omitting data from later stages of breeding (recruitment) can greatly underestimate seasonal fitness declines.


Keywords

Date hypothesis, Farmland bird, Phenology, Quality hypothesis, Reproductive performance

Last updated on 2019-15-10 at 03:10