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Albatross populations in peril? A population trajectory for black-browed albatrosses at South Georgia

Arnold, Jennifer M.; Brault, Solange; Croxall, John P.. 2006 Albatross populations in peril? A population trajectory for black-browed albatrosses at South Georgia. Ecological Applications, 16 (1). 419-432. DOI:10.1890/03-5340

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Abstract/Summary

Simulation modeling was used to reconstruct Black-browed Albatross (Diomedea melanophris) population trends. Close approximations to observed data were accomplished by annually varying survival rates, reproductive success, and probabilities of returning to breed given success in previous years. The temporal shift in annual values coincided with the start of longline fishing at South Georgia and potential changes in krill abundance. We used 23 years of demographic data from long-term studies of a breeding colony of this species at Bird Island, South Georgia, to validate our model. When we used annual parameter estimates for survival, reproductive success, and probabilities of returning to breed given success in previous years, our model trajectory closely followed the observed changes in breeding population size over time. Population growth rate was below replacement (lambda < 1) in most years and was most sensitive to changes in adult survival. This supports the recent IUCN uplisting of this species from “Vulnerable” to “Endangered.” Comparison of pre-1988 and post-1988 demography (before and after the inception of a longline fishery in the breeding area) reveals a decrease in lambda from 0.963 to 0.910. A life table response experiment (LTRE) showed that this decline in lambda was caused mostly by declines in survival of adults. If 1988–1998 demographic rates are maintained, the model predicts a 98% chance of a population of fewer than 25 pairs within 78 years. For this population to recover to a status under which it could be “delisted,” a 10% increase in survival of all age classes would be needed.

Item Type: Publication - Article
Digital Object Identifier (DOI): DOI:10.1890/03-5340
Programmes: BAS Programmes > Global Science in the Antarctic Context (2005-2009) > DISCOVERY 2010 - Integrating Southern Ocean Ecosystems into the Earth System
ISSN: 1051-0761
Format Availability: Electronic, Print
Additional Information. Not used in RCUK Gateway to Research.: Full text not available from this repository
Additional Keywords: Albatrosses ; Thalassarche melanophrys ; Population dynamics ; Fisheries ; Mortality
NORA Subject Terms: Zoology
Ecology and Environment
Date made live: 17 Aug 2007 10:32
URI: http://nora.nerc.ac.uk/id/eprint/6

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