The status and conservation of Cape Gannets Morus capensis

This is the author accepted manuscript. The final version is available from Taylor & Francis via the DOI in this record The Cape Gannet Morus capensis is one of several seabird species that are endemic to the Benguela upwelling ecosystem (BUS), whose populations recently decreased leading to unf...

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Bibliographic Details
Published in:Ostrich
Main Authors: Sherley, R, Crawford, R, Dyer, B, Kemper, J, Makhado, A, Masotla, M, Pichegru, L, Pistorius, P, Roux, J-P, Ryan, P, Tom, D, Upfold, L, Winker, H
Format: Article in Journal/Newspaper
Language:English
Published: Taylor & Francis 2019
Subjects:
Bayesian state-space model
Benguela ecosystem
Conservation status
IUCN Red List
Population decline
Seabird conservation
Bird Island
Online Access:http://hdl.handle.net/10871/39533
https://doi.org/10.2989/00306525.2019.1684396
Description
Summary:This is the author accepted manuscript. The final version is available from Taylor & Francis via the DOI in this record The Cape Gannet Morus capensis is one of several seabird species that are endemic to the Benguela upwelling ecosystem (BUS), whose populations recently decreased leading to unfavourable Red List classifications. Application of JARA, a Bayesian state-space tool for IUCN Red List assessment, to updated information on areas occupied by and nest densities of breeding Cape Gannets at their six colonies suggested the species should be classified as Vulnerable. However, the rate of decrease of Cape Gannets in their most recent generation exceeded that of the previous generation, primarily as a result of large decreases at Bird Island, Lambert’s Bay, and Malgas Island off South Africa’s west coast. Since the 1960s, there has been an ongoing redistribution of the species from northwest to southeast so that c. 70% of the species now occurs at Bird Island, Algoa Bay, on the eastern border of the BUS. Recruitment rather than adult survival may be limiting the present population, although information on demographic parameters and mortality in fisheries is lacking for colonies in the northern BUS. Major present threats to the species include a substantially decreased availability of their preferred prey in the west, heavy mortality of eggs, chicks and fledglings at and around colonies inflicted by Cape Fur Seals Arctocephalus pusillus and other seabirds, substantial disturbance at colonies caused by Cape Fur Seals attacking adults ashore, oiling and disease.

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