Environmental variation and experience-related differences in the demography of the long-lived black-browed albatross.
1. It has been largely demonstrated that demographic performances of animals increase with age or experience as a result of an improvement of foraging skills, an increasing reproductive effort or a selection process. However, little is known about the age or experience-related response of populations to environmental variations. Theoretical studies consider that age-related variations of the performances are greater under more restricting conditions, but this has rarely been tested. 2. We tested this hypothesis on a long-lived species, black browed albatross Thalassarche melanophrys Temminck, using a long-term capture-mark-recapture data set. We investigated the responses of a population to climate, by studying the effects of climatic factors and breeding experience on survival and breeding success. 3. First-time breeders appear to be poorer performers compared with experienced adults, with lower reproductive success and lower survival. In addition, interannual variations of demographic traits were partly explained by climatic indices, reflecting environmental variations. The survival probability of black-browed albatrosses varied with experience and climate, and differences being greater under harsh conditions. By contrast, the reproductive success of inexperienced individuals was affected by climatic fluctuations in the same way as the experienced ones. 4. First breeding event acts as a strong selective process on the highly heterogeneous class of inexperienced individuals, suggesting the increase in survival and breeding success with experience may mainly reflect a reduction in the heterogeneity among individual qualities.
Nevoux
Marie
M
Centre d'Etudes Biologiques de Chizé, Centre National de la Recherche Scientifique, 79360 Villiers en Bois, France. stagbarb@cebc.cnrs.fr
Weimerskirch
Henri
H
Barbraud
Christophe
C
D000818:Animals; D001717:Birds / Q000502:physiology*; D017753:Ecosystem; D011157:Population Dynamics; D013997:Time Factors