Bird Distribution Dynamics - African black oystercatcher in South Africa

Abstract

This is another paper on bird distribution dynamics in Biodiversity Observations. The objective of this series of papers is to report on the ranges of bird species as revealed by the Second Southern African Bird Atlas Project (SABAP2, 2007 onwards) and to describe how their ranges have changed since the first bird atlas (SABAP1, mainly 1987 /- 1991), about two decades apart. The African Black Oystercatcher Haemetopus moquini is neither considered a Red-listed species globally nor regionally however, this endemic and iconic bird was expected to decline due to a variety of anthropogenic and natural influences hence, it received much attention from the scientific community. SABAP data supported the findings of some previous projects that looked at both oytsercacther distribution, dispersion and feeding ecology along South Africa's (SA) coastline as well as that of the alien Mediterranean Mussel Mytilus galloprovincialis. Possible reasons for a relatively recent and northern presence along the SA coastline could be due to southern populations experiencing food shortages during the breeding season that result in seasonal dispersion or carrying capacity on the mainland has been reached. Inside the /oystercatcher's breeding range, the alien mussel serves as an additional food source that probably explains the largest SABAP2 reporting rates along the southern regions of the coastline as this area coincides with the /mussel's distribution range.