期刊
OSTRICH
卷 84, 期 3, 页码 191-198出版社
NATL INQUIRY SERVICES CENTRE PTY LTD
DOI: 10.2989/00306525.2013.863234
关键词
African Penguin; Cape Cormorant; Cape fur seal; Crowned Cormorant; predation mortality; White-breasted Cormorant
类别
资金
- National Research Foundation
- WWF-SA
At Dyer Island, South Africa, observations of predation of seabirds by Cape Fur Seals Arctocephalus pusillus pusillus were made during 2004 and 2006/07. It was estimated that seals killed about 7% of adult African Penguins Spheniscus demersus annually. This may have contributed to the penguin colony not increasing in spite of food becoming more available in its vicinity during an eastward shift of epipelagic fish resources off South Africa at the start of the twenty-first century. Adult penguins were most susceptible to mortality in the breeding season as they returned to feed chicks in the evening. Seals also killed substantial numbers (3-9%) of Cape Cormorant Phalacrocorax capensis fledglings as they left the island, mostly in the morning. The losses of Cape Cormorant fledglings accounted for about 95% of the overall mortality of seabirds attributable to seals. Mortality inflicted by seals on adults of four species of cormorant was negligible and no predation by seals on gulls and terns was observed.
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