Trends in African Black Oystercatcher Haematopus moquini populations between the early 1980s and early 2000s, with consideration of the influence of protected habitats and food availability §

Abstract

The African Black Oystercatcher Haematopus moquini is classified as Near  Threatened because the population size is small (<10 000) and numbers have decreased or were previously recorded as decreasing. Although human activity has increased in many parts of the species’ breeding range, oystercatchers may be benefiting from an increase in the extent of Marine Protected Areas as well as an improved food supply provided by an alien invasive mussel, Mytilus  galloprovincialis. The study reassesses the global population (last assessed in the early 1980s) and, where changes have occurred, to provide an explanation for these changes. Between the early 1980s and early 2000s the global population increased by c. 45% from about 4 600 to about 6 670 birds. On rocky and mixed shores, the presence of Mytilus and protection status explained most of the increase in oystercatchers. At 41 of the 129 study sites numbers of oystercatchers decreased, most probably on account of movement of birds out of areas that experienced human-induced habitat degradation, rather than unsustainable reproductive rates. Overall, there was undoubtedly an improvement in the species’ conservation status; given its current status and trends it may soon be possible to change the status to Least Concern on the IUCN Red List.

Keywords: African Black Oystercatcher, food supply, invasive mussel, population trends, protection