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Senescence in a short-lived migratory bird: age-dependent morphology, migration, reproduction and parasitism

Authors

  • A. P. Møller,

    1. Laboratoire d’Ecologie, CNRS URA 258, Université Pierre et Marie Curie, Bât. A, 7ème étage, 7 quai St. Bernard, Case 237, F-75252 Paris Cedex 05, France, and Departamento de Ciencias Morfologicas y Biologia Celular y Animal, Universidad de Extremadura, E-06071 Badajoz, Spain
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  • F. DE Lope

    1. Laboratoire d’Ecologie, CNRS URA 258, Université Pierre et Marie Curie, Bât. A, 7ème étage, 7 quai St. Bernard, Case 237, F-75252 Paris Cedex 05, France, and Departamento de Ciencias Morfologicas y Biologia Celular y Animal, Universidad de Extremadura, E-06071 Badajoz, Spain
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A. P. Møller, Laboratoire d’Ecologie, CNRS URA 258, Université Pierre et Marie Curie, Bât. A, 7ème étage, 7 quai St Bernard, Case 237, F-75252 Paris, Cedex 05, France. Tel. (+33) 1 44 27 25 94. Fax: (+33) 1 44 27 35 16. E-mail: AMOLLER@HALL.SNV.JUSSIEU.FR

Abstract

1. Senescence reflects age-dependent changes in residual reproductive value. Annual survival rates of the barn swallow Hirundo rustica L. increased from 1- to 2-year-old individuals, but decreased among 5 years old or older individuals. Estimates of age-dependent reproductive value showed a similar pattern.

2. Longitudinal data from two long-term population studies were used to test whether a number of different measures of performance (condition-dependent morphological traits, migratory performance, reproductive success, intensity of parasitism) changed among individuals when reaching old age.

3. The length of the outermost tail feathers (a secondary sexual character) decreased among old individuals, while two measures of individual developmental instability increased with age. Migratory performance decreased in old barn swallows as reflected by a delay in spring arrival at the breeding grounds. Reproductive performance measured as seasonal reproductive success decreased with age. The intensity of infestations with an haematophagous mite and a mallophagous ectoparasite increased among old barn swallows.

4. These results suggest that the condition-dependent secondary sexual character, developmental stability, and measures of migratory and reproductive performance deteriorated, and the frequency of parasitism increased among old individuals. Ageing was thus associated with a general deterioration of performance.

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