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Journal ArticleDOI

Supplementary notes on the biology of the large biros of prey of embu district, kenya colony

03 Apr 2008-Ibis (Blackwell Publishing Ltd)-Vol. 97, Iss: 1, pp 38-64
TL;DR: The fluctuations of population in an area of 146 square miles in Embu district, where a census of eagles was carried out in 1950, are described and discussed and the inter-relations of various species are discussed.
Abstract: Summary. 1 The present paper is supplementary to that in ‘Ibis’ 94 and 95. 2 The fluctuations of population in an area of 146 square miles in Embu district, where a census of eagles was carried out in 1950, are described and discussed fur 951–52. 3 The inter-relations of various species are discussed, particularly for Aquila wahlbergi and Lophaetus occipitalis. 4 General accounts of breeding biology are given for Sagittarius serpentarius, Aquila wahlbergi, Hieraaetus ayresi and Terathopius ecaudatus, and supplementary data for Aquila verreauxi, Hieraaetus spilogaster, Polemaetus bellicosus, Stephanoaetus coronatus, Lophaetus occipitalis, Circaetus cinereus and Circaetus pectoralis. These accounts are given under the following heads:— 1 General notes on adults. 2 Nests and nest-building. 3 The incubation period. 4 The fledging period: (a) general, (b) development of the young, (c) parental behaviour, (d) food. 5 The post-fledging period. 5 Special problems of breeding biology are discussed under the following heads: (1) Display; (2) Eagle-weaver-bird nesting-associations; (3) Feeding rates of female and eaglet; (4) Breeding seasons; (5) Breeding success and replacement rate.
Citations
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Journal ArticleDOI
01 Dec 1996-Ostrich
TL;DR: Herholdt, JJ, Kemp, AC & Du Plessis, D 1996 Aspects of the breeding status and ecology of the Bateleur and Tawny Eagle in the Kalahari Gemsbok National Park Ostrich 67:126-137 The nesting s
Abstract: Herholdt, JJ, Kemp, AC & Du Plessis, D 1996 Aspects of the breeding status and ecology of the Bateleur and Tawny Eagle in the Kalahari Gemsbok National Park Ostrich 67:126-137 The nesting s

10 citations

Journal ArticleDOI
01 Dec 1965-Ostrich
TL;DR: In this paper, some observations on the BATELEUR TERATHOPIUS ECAUDATUS (DAUDIN) Ostrich have been discussed and discussed.
Abstract: (1965). SOME OBSERVATIONS ON THE BATELEUR TERATHOPIUS ECAUDATUS (DAUDIN) Ostrich: Vol. 36, No. 4, pp. 203-213.

10 citations

01 Jan 2007
TL;DR: The diet of non-breeding period has proved to influence the healthy of birds, body condition and the reproductive output in the subsequent breeding attempt as mentioned in this paper, leading to a strong limitation of both density and survival of a number of bird species.
Abstract: raptors remains largely unknown since most of diet studies are usually restricted to a half of the year, the breeding season, probably due to the easiness for recovering food data related to the association of individuals to nesting sites. Contrary, during the non-breeding season birds are difficult to locate and information on diet is scarce, causing lack in overall knowledge and comprehension of feeding habits (Cramp and Simmons, 1980; del Hoyo et al., 1994; Ferguson-Lees and Christie, 2001). Because of food is one of the main limiting factors for birds of prey (Newton, 1979), this shortage in basic information during a long life-period of such species should be urgently addressed. In this sense, the diet of nonbreeding period have proved to influence the healthy of birds, body condition and the reproductive output in the subsequent breeding attempt (Newton, 1979; Gonzalez, 1991), finally leading to a strong limitation of both density and survival of a number of bird species (see a review in Newton, 1998). Hence the study on non-breeding diet in raptors, a group of species usually threatened (del Hoyo et al., 1994; Tucker and Heath, 1994), is not only an important aspect to promote the ecology knowledge but also a necessary tool to plan adequately conservation measures. The Bonelli s eagle Hieraaetus fasciatus is an endangered bird of prey (Tucker and Heath, 1994; Real, 2004) inhabiting the Mediterranean coast, Middle East and southern Asia (del Hoyo et al., 1994; Ferguson-Lees and Christie, 2001). Dietary studies on this species are frequently related to the breeding season and restricted around European continent (Jordano, 1981; Palma et al., 1984; Fernandez and Insausti, 1986; Real, 1987; Salvo, 1988; Simeon and Wilhelm, 1988; Rico et al., 1990; Real, 1991; Gil-Sanchez et al., 1994; Leiva et al., 1994; NON-BREEDING FEEDING ECOLOGY OF TERRITORIAL BONELLI S EAGLES HIERAAETUS FASCIATUS IN THE IBERIAN PENINSULA

10 citations

Journal ArticleDOI
01 Mar 1964-Ostrich
TL;DR: In this paper, the authors discuss the BROWN SNAKE-EAGLE CIRCAETUS CINEREUS and its role in the discovery of the Rainbow Serpent.
Abstract: (1964). OBSERVATIONS ON THE BROWN SNAKE-EAGLE CIRCAETUS CINEREUS. Ostrich: Vol. 35, No. 1, pp. 22-31.

10 citations

Journal ArticleDOI
01 Sep 1995-Ostrich
TL;DR: There was no correlation between pairs in occupancy of territory, productivity or development periods of young: this confirms the flexible breeding abilities of the Secretarybird Sagittarius serpentarius which are unusual for such a large bird.
Abstract: Summary Kemp, A. C. 1995. Aspects of the breeding biology and behaviour of the Secretarybird Sagittarius serpentarius near Pretoria, South Africa. Ostrich 66: 61–68. Secretarybirds in three adjacent territories were monitored from 1977 to 1988 on grass- and croplands near Pretoria, South Africa. Most observations of breeding biology and behaviour confirmed or extended previous studies. There was no correlation between pairs in occupancy of territory, productivity or development periods of young: this confirms the flexible breeding abilities which are unusual for such a large bird. Some aspects of breeding biology (egg shape and texture, watering of chicks) and behaviour (Wings open and Up-down greeting displays) may be homologous with storks and important in understanding the phylogeny and evolution of the Sagitariidae and other diurnal raptors.

9 citations

References
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Journal ArticleDOI
03 Apr 2008-Ibis
TL;DR: The observed timing of breeding seasons can be secured only by external factors regulating an internal rhythm, and in some communities and categories of birds the “reasons” for the observed breeding seasons are intelligible.
Abstract: Summary. 1 For the present purpose Africa is divided into everyreen, semi-arid and intermediate (deciduous) types of count?, all of which occur in all latitudes south of the Sahara. 2 “Breeding season” is limited to the months during which eggs are laid by the species concerned in the given area and all records are interpreted accordingly. As a basis for ascertaining the curve of breeding activity in a given area through the year the number of species laying in each month has been ascertained and calculated as a percentage of the total for all species for the whole year. 3 A definite peak in the curve of breeding activity is evident everywhere except in certain areas within about four degrees of the Equator. 4 In one part of this inner tropical belt there may be no distinct breeding season for must groups of birds (Congo), but in East Africa a double breeding season is the rule, with peaks coinciding with the two rainy seasons. 5 Even so close to the Equator as 5°s. the (single) breeding season in evergreen forest is as restricted as in other types of country and its time-relation to the rains varies locally. 6 In the “ intermediate” type of country characterized by 4–6 months drought each year the timing of the peak breeding season varies from the end of the rains, at Cape Town, to the start of the rains in Natal and several weeks before the rains in areas 23° - 10° S. 7 The key to this local difference is that at Cape Town the rains fall in the cold season, so that vegetation and insects are slow to flush. In the warmer conditions in which the rains begin in Natal the flush comes at once. And further north the dominant vegetation and its associated insects flush towards the end of the drought and well in advance of the rains. 8 From Natal northwards the breeding season for all birds combined shows a progressively less marked peak. The reason is that the seasons of certain ecological categories (1) water birds, (2) raptors and scavengers, (3) ground birds, (4) grass birds, (5) the other birds, tend to diverge. 9 The raptors and scavengers are everywhere the earliest breeders, the biggest species laying by the middle of the dry season. The water birds lay to a large extent towards the end of the rain, and after. The ground birds tend to lay as soon as the grass fires are over and before the heavy rains have induced a lush growth of herbage. The grass birds lay later than most-others, when the grass has grown high. 10 In semi-arid areas the breeding seasons are on the whole similar to the foregoing, with most birds breeding when the vegetation flushes, whether just before or after rain has fallen. But the “semi-and” birds are notably sensitive to rainfall; breeding that has begun is checked if the rains are interrupted. 11 In some communities and categories of birds the “reasons” for the observed breeding seasons are intelligible, the best food-supply or the safest nesting apparently being secured. In others the reasons are not obvious; and the degree to which the breeding seasons are restricted is often incomprehensible. 12 The observed timing of breeding seasons can be secured only by external factors regulating an internal rhythm. Day-length, rainfall and humidity, temperature and visual stimuli are each considered briefly. Each may be effective on some species in some areas, but no one generally.

123 citations

Journal ArticleDOI
03 Apr 2008-Ibis
TL;DR: The species of eagles occurring in Embu district are detailed, with general notes on the methods and scope of the study, and the inter-relations of the various species are discussed from the points of view of territorial agressiveness and competition for prey.
Abstract: SUMMARY. 1 The species of eagles occurring in Embu district are detailed, with general notes on the methods and scope of the study. 2 The vegetation and climate of Embu district are described, and their effect upon eagles is discussed. 3 Population and inter-relations. The actual population of eagles and of the Secretary Bird in an area of approximately 146 sq. miles is given and their remarkable local concentrations are described. The inter-relations of the various species are discussed from the points of view of territorial agressiveness and competition for prey. 4 Detailed accounts are given of the breeding biology of Sagittarius serpentarius, Aquila verreauxi, A. wahlbergi, Hieraaetus spilogaster, Polmaetus bellicosus, Stephano-aetus coronatus and Circaetus cinereus, and some information for Terathopius ecaudatus, Circaetus pectoralis, and Aquila rapax, Hieraaetus ayresi, Lophaetus occipitalis, and Cuncuma vocifer. The headings for each species include: “Nests and nest-building”, “Incubation period”, “Fledging period” (with special attention to food), and “Post-fledging period”. 5 The following special aspects of breeding behaviour are described and discussed: (1) Display, (2) Use of green branches, (3) Breeding seasons, (4) Breeding success, (5) Breeding frequency.

39 citations

Journal ArticleDOI
03 Apr 2008-Ibis

22 citations

Journal ArticleDOI
03 Apr 2008-Ibis
TL;DR: Breeding records in Tropical Africa show, when analysed with reference to egg-dates, that as a rule in each area the young get through their fledging period, or at least the later, unbrooded part, during the local cool dry season.
Abstract: Summary An account is given of one hundred hours of observations at a Bateleur'a nest in north-eastern Tanganyike Territory. The adults were a white-backed bird and a chestnut-backed, with a sub-adult; probably over three years old, in association with them. The youngster took 130 dap to fledge. During at least part of the time all its food was brought by the white-backed adult. When the fledgling was about one month old its feeds averaged about one in eight hours; during its last week in the nest feeds were nearly three times as frequent. Literature and unpublished data are reviewed in relation to special points of interest, viz.:— Slow development and maturation accords with longevity. Fledging period apparently longer than authentically recorded for any land bird. First wing-moult may have started before first flight. Tail length is greater in proportion to wing in juveniles than in adults. Proportion of white-becks to chestnut-backs differs in parts of Africa, being least in South africa. White-tailed birds seem confined to Sudanese semi-desert belt. Voice, flight habits and wing-noises seem to differ in parts of Africa. Food comprises both carrion and live prey, especially snakes, but not poultry or other birds. Claws are not less sharp than those of Stephanoaetus and Polemaetus. Breeding records in Tropical Africa show, when analysed with reference to egg-dates, that as a rule in each area the young get through their fledging period, or at least the later, unbrooded part, during the local cool dry season. Psychologically the Bateleur is most peculiar: in the wild it is shy of man, sociable with big birdv of its own and other species, and breeding birds tolerate sub-adults: in captivity it becomes unusually tame, has a grecting ceremony for friends and likes to be handled.

11 citations