Browsing by Author "Broekhuysen, G J"
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- ItemOpen AccessThe behaviour of the bontebok Damaliscus Dorcas Dorcas, with special reference to territorial behaviour(1970) David, Jeremy Hugh Markham; Broekhuysen, G JFieldwork for this study was commenced during the end of January 1969 and terminated in mid-April. 1970. It was conducted on a full time basis and follow-up visits were made to the Park at intervals duririg the remainder of 1970. The study was carried on exclusively in the Bontebok National Park which contains by far the largest herd of bontebok in the country. Visibility in the Park is good and all observations were made from a vehicle with the aid of binoculars at distances ranging from about 30 m to over 400 m. Most animals were tolerant of a motor vehicle but there were one or two exceptions, particularly territorial males whose territories were situated away from the roads and who were therefore unused to being approached closely by vehicles. Females were on the whole more nervous than males and especially females with new born lambs were very nervous and would run from a vehicle at 100 m or more.
- ItemOpen AccessThe biology of the Cape Weaver Ploceus Capensis with special reference to its polygnous mating system(1973) Elliott, Clive Christopher Hugh; Broekhuysen, G JThe study of the biology of the Cape Weaver Ploceus capensis was carried out mostly in the winter rainfall area of the S. W. Cape in South Africa. This report shows that the species has conspicuous plumage dimorphism and some physical dimorphism in the sexes, and that the male only achieves full plumage at about 22 months old. The female reproduces at one year of age. Possible reasons for this deferred maturity in the male are discussed. It is concluded that the high competition for mates and the advantage to the young male in nest-building and territorial activities on the periphery of the colony are the main pressures for deferred maturity. A detailed investigation of breeding seasons in the species is reported and it is shown how aspects of the clutch-size and incubation strategy are apparent adaptations to polygyny and its concomitant fluctuating food source. The ultimate and proximate factors influencing the breeding season are also discussed. This study presents the first comprehensive study of moult in passerines in southern Africa. The more important findings are that moult is slower than in the northern hemisphere and that there are differences in the start of moult in different age/ sex classes. The food situation in the Cape Weaver is reported and it is shown how the species is adapted to a wide variety of insect and vegetable foods. The chicks are fed almost entirely on insect food except towards the end of the season. Weight fluctuations throughout the year are small and it is suggested that this shows that food fluctuations are smaller and present a much less difficult situation for the passerine in South Africa than in the northern hemisphere. Evidence is presented which shows a sex ratio of 1 : 1 in nestlings though there are some interesting tendencies revealed in the data. In full-grown birds, there is a slight excess of males probably throughout the year. It is pointed out that this is the opposite to what would be "required" by a polygynous mating system. Contrary to general theories, it is proposed that males do not suffer higher mortality than females during the breeding season. In fact it is suggested that females suffer higher mortality both in and out of the breeding season, partly as a result of their subordinate social position in all circumstances except at the nest. The territorial and courtship behaviour of the Cape Weaver are described and it is shown how aspects of the behaviours vary according to the time in the season and the pair-bond circumstances. A social hierarchy study on the species is discussed. Finally, the special aspect of the study, the unusual polygynous mating system is investigated in detail. A possible evolutionary sequence for the development of polygyny in passerines is proposed. This stresses the importance of the type of food source and the development of coloniality or gregariousness as the primary prerequisite. A feature of the thesis is the attempt to keep the theme of the adaptations to polygyny in mind through all the studies of the other parts of the Cape Weaver's biology.
- ItemOpen AccessBreeding behaviour and polygyny in the Red Bishop bird Euplectes orix (L.)(1973) Craig, Adrian John Fergus Knott; Broekhuysen, G JThe red bishop bird, Euplectes orix, is a widespread and locally abundant member of the weaver family, the Ploceidae. It is found over most of Southern Africa, and as, far north as Uganda in the Eastern savannah belt. Large flocks may be found in association with other seedeaters, and the breeding colonies in reeds or tall grass in marshy areas may contain from five to several thousand birds. Recently it has also been recorded as nesting in standing crops in some areas. The adult birds are sparrow-sized, 12-15 cm in length and weighing 20-30 gm. The wing-length in the males ranges from 70-83 mm, and in females from 64-72 mm. Mackworth- Praed and Grant (1962) mention that birds from the Cape are larger, and that there appears to be a decrease in size of birds further north; measurements taken in this study seem to confirm this. During most of the year, both sexes are a mottled light brown colour, with a pale streak above the eye, and the underside pale to almost white, with darker streaks. However, at the beginning of the breeding season the adult males moult into their striking nuptial plumage: the abdomen and face mask are black, while the crown, throat, breast, rump, upper and under tail coverts are scarlet. The mantle feathers are tawny, but the wings and tail remain brown. The bill colour also changes from flesh-coloured to black. Hall and Moreau (1970), whose nomenclature is used for all the passerine species mentioned, regard three species Euplectes orix, franciscus and nigroventris as comprising the "orix superspecies". All three retain the brown wings and tail in the male breeding dress, but show variations in the extent of the red and black plumage. There is no apparent overlap in their ranges, or any evidence of inter-breeding. Two further species, E. hordeceu and E. gierowii, differ in that the wings and tail of the male are also black during the breeding season. Although slightly larger, their plumage is in other respects very similar, and these five species are termed a "species group". There is surprisingly little published information on any of these species. Lack (1935) first described territorial behaviour and polygyny in Euplectes hordeaceus, and later Moreau and Moreau (1938) and Fuggles-Couchman (1942) compared the ecology of E. hordeaceus and E. nigroventris. Skead (1956) produced a valuable basic study of E. orix, and showed it to be polygynous. Emlen (1957) made observations on several Euplectes species in Rhodesia, but the species orix and hordeaceus are confused in his paper, and it is not always clear which he is referring to. Later studies dealing with E. orix by Brooke (1964), Schmidt (1968) and Woodall (1971) are primarily concerned with clutch size, breeding seasons and nesting success, rather than behaviour. However, Crook (1962, 1963, 1964) has produced an important series of papers comprising a comparative study of behaviour in the entire weaver family. He refers mostly to the genus Euplectes, but also quotes observations on individual species, including E. orix. Collias and Collias (1964) have described nest-building behaviour in the weavers, but also mainly at the generic level.
- ItemOpen AccessThe ecological life history of the Cape Bulbul(1970) Liversidge, Richard; Broekhuysen, G JThe study of the ecological life history of the Cape Bulbul Pycnonotus capensis was carried out in 20 hectares of coastal dune forest near Port Elizabeth, South Africa. Results from four years 1959 to 1962 are given in detail and only the number of breeding pairs present in 1958 have been used from observations that year. The Cape Bulbul is one of three closely related species of a predominantly tropical family. Intra specific breeding is rare and occurs only where man has altered the habitat. Distribution has altered slightly in 150 years where colonisation has occurred. Several conditions may influence distribution, the species is mainly limited to within winter or all year round zones of rainfall. Population of breeding pairs varies from nine to 19 pairs. It is the commonest species in the area. There is a 25% annual adult mortality with life expectancy of an adult about three years. Competition for food is negligible. Predators concern mainly the nesting cycle. Clutch size which is two or three is not regulated by food supply or population changes. Main changes are due to emigration and immigration which is apparently influenced by density-independent factors.
- ItemOpen AccessSome aspects of the biology of the tobacco beetle, Lasioderma serricorne (F), (Coleoptera : Anobiidae)(1951) Rayner, Vivienne Iris; Day, J H; Broekhuysen, G JSince about 1866 the "tobacco beetle," Lasioderma serricorne, has been recognized as a pest of considerable economic importance. In addition to cured tobacco, the larval stage attacks a great variety of other materials of both plant and animal origin. Much of the work done on the biology of this beetle is fragmentary and not precisely recorded. The present author has aimed at correlating as much of the available valid information as possible and supplementing it with original records. Further, most previous investigations have centred on control rather than bionomics. But a sound knowledge of bionomics is needed as a basis for an effective scheme or control. Therefore, as research had to be limited in some way, in this paper attention has been paid primarily to bionomics (with some relevant morphology). The section on control comprises only a few original observations, and this aspect offers a wide field for future research.
- ItemOpen AccessSome aspects of the biology, ecology and control of the Pine Brown Tail Moth, Euproctis terminalis, Walk(1955) Grobler, Johannes Hermanus; Broekhuysen, G J
- ItemOpen AccessSome aspects of the life history and bionomics of the Fig moth, Ephestia cautella (Wlk.), and some comparisons with the mediterranean flour moth, E. kuhniella (Zell) and the tobacco moth, E. elutella (Hb.)(1951) Newman, Patricia Ann; Day, J H; Broekhuysen, G JIn this paper, the morphological differences among the three common species of Ephestia have been confirmed by the present author, so that they may be easily identified. The life history of E. cautella has also been worked out, as well as some aspects of the life history of E. elutelle. and E. kuhniella. These three species have been found to differ at certain points of their life histories. Finally, the results of other authors have been compared with the findings of the present author.