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W. R. Siegfried

Bio: W. R. Siegfried is an academic researcher from University of Cape Town. The author has contributed to research in topics: Egret & Population. The author has an hindex of 17, co-authored 40 publications receiving 870 citations. Previous affiliations of W. R. Siegfried include Stellenbosch University & Percy FitzPatrick Institute of African Ornithology.

Papers
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Journal ArticleDOI
TL;DR: In this paper, the authors consider current efforts to rescue, clean and rehabilitate oiled seabirds as contributing little to conservation in real terms, even though the activity has an important humanitarian and educational function.

122 citations

Journal ArticleDOI
TL;DR: In this article, the location of noda of nature reserves aimed at protecting the floral diversity of Fynbos vegetation in the Cape Floral Region, in South Africa, using distributional data on the Proteaceae.

101 citations

Journal ArticleDOI
01 Mar 1972-Ostrich
TL;DR: In this paper, the authors discuss the breeding success and production output of the CATTLE EGRET, and present an overview of the evolution and production of the cow's genes.
Abstract: (1972). BREEDING SUCCESS AND REPRODUCTIVE OUTPUT OF THE CATTLE EGRET. Ostrich: Vol. 43, No. 1, pp. 43-55.

79 citations

Journal ArticleDOI
TL;DR: In this paper, it is suggested that the gregarious roosting of A. ibis has been evolved primarily in relation to the food situation, and that communal roasting can be viewed as an extension of this behavior.
Abstract: Summary Roosting birds generally have two main requirements: protection from predators and shelter from adverse weather. The paper summarizes the results of some preliminary investigation into the significance of these conventions as they apply to Ardeola ibis. Communal roosting in birds has been little studied, and the function of this phenomenon is not yet understood. In A. ibis the whole advantage of social roosting cannot be explained only in terms of protection from predators, shelter for adverse weather and/or conservation of energy at night. Data are presented in support of the claim that in A. ibis an important, if not the main, function of communal roosting is in assisting individuals to maintain contact with each other. The value of this behaviour rests in more efficient finding and exploitation of localized food resources. It is suggested that the gregarious roosting of A. ibis has been evolved primarily in relation to the food situation, and that communal roosting can be viewed as an extension...

60 citations

Journal ArticleDOI
TL;DR: The diet of cattle egrets feeding in man-made pastures in the south-western Cape Province, South Africa is reported on, finding irrigated pasture constitutes, by far, the species' most impor- tant feeding ground in the study-area.
Abstract: 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.

54 citations


Cited by
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Journal ArticleDOI
TL;DR: Some basic principles for conservation planning are emerging from recent systematic procedures for reserve selection, and these principles will help to link intention and practice.
Abstract: The intention and practice of conservation reserve selection are different. A major reason for systems of reserves is to sustain biological diversity. This involves protecting examples of as many natural features, e.g. species, communities or environments, as possible. In reality, however, new reserves have rarely been dedicated for their representation of features. Furthermore, the opportunism that has characterized the development of reserve systems can actually jeopardize the representation of all features in reserves through the inefficient allocation of limited resources. More systematic approaches are essential if reserves are to play their role in protecting biodiversity. Some basic principles for conservation planning are emerging from recent systematic procedures for reserve selection. These principles will help to link intention and practice.

1,028 citations

Journal ArticleDOI
03 Apr 2008-Ibis
TL;DR: Evidence is presented to support the hypothesis that communal roosts, breeding colonies and certain other bird assemblages have been evolved primarily for the efficient exploitation of unevenly-distributed food sources by serving as “information-centres”.
Abstract: Summary Evidence is presented to support the hypothesis that communal roosts, breeding colonies and certain other bird assemblages have been evolved primarily for the efficient exploitation of unevenly-distributed food sources by serving as “information-centres”. Predation-pressure is regarded as being the most important factor “shaping” the assemblages. The shaping involves the choice of inaccessible or otherwise safe sites, optimum dispersal, mutual awareness of attack and joint defensive tactics, and serves to minimise the vulnerability to predation which would otherwise result when birds mass together in conspicuous, and often predictable centres.

977 citations

Journal ArticleDOI
01 Jun 2015-Ardea

746 citations

Journal ArticleDOI
TL;DR: In this paper, the main reasons for land reservation persist despite clearly stated representation goals, improving data bases, and systematic techniques for reserve selection, and there are two main disadvantages of such ad hoc approaches to reserve planning: the bias in the content of regional reserve systems, leaving some species, communities, or ecosystems without protection, often the ones most in need of strict reservation.
Abstract: A major reason for land reservation has been the relative lack of value of selected sites for major commercial land uses or for human habitation. Other important reasons include scenery, recreation, tourist potential, the influence of lobby groups, and historical protection for uses such as hunting or water supply. There are two main disadvantages of such ad hoc approaches to reserve planning. One is the bias in the content of regional reserve systems, leaving some species, communities, or ecosystems without protection, often the ones most in need of strict reservation. The second is that ad hoc reservations can make the goal of representing regional biodiversity more expensive, reducing the likelihood of protecting many elements of biodiversity. Ad hoc approaches to reservation persist despite clearly stated representation goals, improving data bases, and systematic techniques for reserve selection. The main causes need to be understood and addressed if the potential value of reservation for protecting biodiversity is to be realized. La principal razon para la reservacion de tierras ha sido la falta relativa del valor de los sitios seleccionados para usos comerciales o habitacionales para el hombre. Otras razones importantes incluyen el panorama paisajistico, la recreacion, el turismo potencial, la influencia de grupos de lobby y la proteccion historica para usos tales como caza o provision de agua. Existen dos desventajas mayores de estas formas ad hoc de planificacion de reservas. Una es el sesgo dentro del sistema regional de reservas, dejando ciertas especies, comunidades o ecosistemas sin proteccion, muy a menudo aquellas con mayor necesidad de reservas estrictas. La segunda es que las reservas ad hoc hacen que el objetivo de representar la biodiversidad regional sea mas costoso, reduciendo la posibilidad de proteger muchos elementos de la biodiversidad. Los enfoques ad hoc de reservar persisten a pesar de objetivos de representatividad claramente delineados, el mejoramiento de las bases de datos y las tecnicas sistematicas para la seleccion de reservas. Las causas principales deben ser entendidas y consideradas si se quiere lograr el valor potencial de reservar y proteger la biodiversidad.

571 citations