Research Papers

South Africa's coastal-breeding white-breasted cormorants: population trends, breeding season and movements, and diet

Published in: African Journal of Marine Science
Volume 35, issue 4, 2013 , pages: 473–490
DOI: 10.2989/1814232X.2013.845603
Author(s): RJM CrawfordBranch: Oceans and Coasts, Department of Environmental Affairs, South Africa, RM RandallSouth African National Parks, South Africa, PA WhittingtonEast London Museum, South Africa, L WallerCapeNature, South Africa, BM DyerBranch: Oceans and Coasts, Department of Environmental Affairs, South Africa, DG AllanDurban Natural Science Museum, South Africa, C FoxEzemvelo-KZN Wildlife, South Africa, AP MartinDepartment of Zoology, South Africa, L UpfoldBranch: Oceans and Coasts, Department of Environmental Affairs, South Africa, J VisagieCapeNature, South Africa, S BachooEzemvelo KZN Wildlife, South Africa, M BowkerSchool of Life Sciences, South Africa, CT DownsSchool of Life Sciences, South Africa, R FoxAddo Elephant National Park, South African National Parks, South Africa, J HuisamenCapeNature, South Africa, AB MakhadoBranch: Oceans and Coasts, Department of Environmental Affairs, South Africa, WH OosthuizenBranch: Oceans and Coasts, Department of Environmental Affairs, South Africa, PG RyanPercy FitzPatrick Institute of African Ornithology, South Africa, RH TaylorSchool of Life Sciences, South Africa, JK TurpieAnchor Environmental Consultants, South Africa

Abstract

White-breasted cormorants Phalacrocorax [carbo] lucidus breed around South Africa's coast and at inland localities. Along the coasts of the Northern, Western and Eastern Cape provinces, numbers breeding were similar during the periods 1977–1981 (1 116 pairs at 41 localities) and 2008–2012 (1 280 pairs at 41 localities). Along the coast of KwaZulu-Natal (not counted in 1977–1981), 197 pairs bred at nine localities in 2008–2012, when the overall number breeding around South Africa's coastline was about 1 477 pairs. Between the two study periods, numbers decreased in the Northern and Western Cape provinces following the loss of several breeding localities, but they increased in the Eastern Cape. In the Western Cape, however, numbers were stable east of Cape Agulhas and at nine well-monitored West Coast localities that were surveyed from 1978 to 2012. White-breasted cormorants breed throughout the year, with breeding at some localities more seasonal than at others and the timing of peaks in breeding varying at and between localities. In the vicinity of Saldanha Bay/Langebaan Lagoon (Western Cape), in Algoa Bay (Eastern Cape) and in northern KwaZulu-Natal, it is likely that birds moved between breeding localities in different years, although breeding often occurred at the same locality over several years. Human disturbance, presence of predators, competition for breeding space and occurrence of breeding by other waterbirds may influence movements between colonies. Securing sufficient good habitat at which white-breasted cormorants may breed will be important for conservation of the species. The species may breed at an age of 4 years, possibly younger. The bulk of their diet around South Africa's coast consists of inshore marine and estuarine fish species that are not intensively exploited by humans.

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