Waterbirds at the Theewaterskloof Dam, Western Cape, South Africa, 1993–2005

Abstract

With a perimeter of 82km, the Theewaterskloof Dam is the largest dam in the Western Cape. This paper, based on midsummer and mid-winter surveys between 1993 and 2005, assesses the importance of the dam for waterbirds. The median numbers of waterbirds in summer and winter were 3 086 and 1 321, respectively. Fifty-eight species were recorded, 35 of them on at least half of the summer or winter surveys. The proportion of Egyptian Geese Alopochen aegyptiaca in summer increased from 47% in the first four years to 88% in the final four years, and reached 94% in summer 2005. Numbers of most colonially-nesting waterbirds decreased over the period assessed; this is attributed to the ongoing decay of trees that were left standing when the dam was constructed. In 2005, 25 years after completion, Theewaterskloof Dam is considered not to have reached the ‘mature lake' phase, because species composition patterns remain unstable. Despite its size, the dam is of minor conservation importance to waterbirds in the Western Cape.

Ostrich 2006, 77(3&4): 170–174