1971/08/01 by W. R. Siegfried · 4 citations
Environmental Science · #Avian ecology and behavior
paper · doi:10.2307/2402882
openalex publication_date 1971/08/01 · openalex created_date 2025/10/10 · openalex updated_date 2025/11/06
incidents. Often it is based on descriptions of 'unusual' predatory behaviour, or of examination of numerically small and unrepresentative stomach-content samples. Ex- ceptions were the investigations carried out in Egypt by Kirkpatrick (1925) who examined 139 stomachs, and Kadry Bey (1942) who examined 498. This paper reports on the diet of cattle egrets feeding in man-made pastures in the south-western Cape Province, South Africa. The study-area was located near the town of Stellenbosch (330 57'S, 180 50'E). For the evaluation of the food of independent, free-flying egrets, specimens were ob- tained by shooting. They were collected in 10 out of every 12 months over a period of 3 years, within a radius of about 30 km of Stellenbosch. No birds were collected in October and November because: (a) egrets were relatively scarce in and around Stellen- bosch in those months; (b) the birds breed during those months and disturbance to breeders near their nesting colonies, and the imposed artificial mortality, would have affected the results of concurrent investigations, aimed at determining the species' reproductive success; and (c) stomach contents obtained from adult birds with young might have led to a distorted picture of the adults' true diet, since adults might have been purposely selecting food items particularly suitable for feeding to their nestlings. Most of the samples were obtained from birds collected whilst feeding in one type of habitat, viz. dairy-cattle paddocks, primarily planted with kikuyu grass (Pennesetum clandestinum). These pastures are irrigated in summer, either by overhead sprinklers or by gravitational flooding, or both. The advantage of concentrating collection in this way was basically twofold. Firstly, irrigated pasture constitutes, by far, the species' most impor- tant feeding ground in the study-area. Secondly, a comparative analysis of the food resources of this habitat and the diet of the birds and their numbers could be studied (Siegfried, in preparation). A limited number of food samples were obtained from birds frequenting feeding places other than stock-grazing pastures.