Long-term trends in the population size of king penguins at Crozet archipelago: environmental variability and density dependence?

International audience We examined the growth rate of the breeding population of king penguins of Crozet archipelago over 41 years. Most colonies showed positive growth rates from the 1960s. However, there was evidence for a decrease in the larger colonies since the early 1990s, and for lower growth...

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Bibliographic Details
Main Authors: Barbraud, Christophe, Delord, Karine, Weimerskirch, Henri
Other Authors: Centre d'études biologiques de Chizé (CEBC), Centre National de la Recherche Scientifique (CNRS)
Format: Article in Journal/Newspaper
Language:English
Published: HAL CCSD 2004
Subjects:
geo
Online Access:https://hal.archives-ouvertes.fr/hal-00186860
Description
Summary:International audience We examined the growth rate of the breeding population of king penguins of Crozet archipelago over 41 years. Most colonies showed positive growth rates from the 1960s. However, there was evidence for a decrease in the larger colonies since the early 1990s, and for lower growth rates in the smaller colonies during the 1990s. The overall population size was estimated using log linear models, and the average annual growth rate was +6.3% for the 41-year period. Four change points were detected in the annual growth rate: +21.1% during 1978–1985, +4.3% during 1985–1995, 19.2% during 1995–1999, and +10.9% during 1999–2003. Time-series analyses of the population-size estimates and the relationship between growth rate and population size both indicated density-dependence in population growth rate. Variations in population sizes are also discussed in relation to environmental fluctuations. Our results suggest that important changes occurred over the past 10 years. 8 pages