摘要:

Mendelsohn, J. M. 1983. Social behaviour and dispersion of the Blackshouldered Kite.Ostrich54: l–18. Colour-marked Blackshouldered KitesElanus caeruleuswere studied at Settlers in the Springbok Flats, South Africa. Males usually established territories where females joined them as mates after moving around between territorial males. There were always more resident males than females. Territories were exclusive nesting and hunting areas. The number of territories decreased, but mean territory size increased during the study. Unpaired kites held smaller territories than other residents. Males usually established territories when occupied areas fell vacant, but females usually paired when most other pairs were starting to breed. Both sexes abandoned territories when food supply was poor. Unpaired males deserted more frequently and had longer temporary absences than paired or breeding males. Most kites (86%) were resident for periods of less than 100 days. Females spent either most or very little of their time breeding. The longer males were resident, the greater the proportion of their time spent paired and breeding. Population size varied between 19 and 35 kites ([Xbar]=26); about 13% of the population was replaced each half-month. More nomads visited the study area when feeding and breeding conditions were good. After deserting territories, males usually became nomads while females probably moved to new territories. The social organization of Blackshouldered Kites is discussed with reference to food supply (Mendelsohn 1982), population dynamics, and breeding biology (Mendelsohn 1981).

ISSN:0030-6525    

DOI:10.1080/00306525.1983.9634437

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Geldenhuys, J. N. 1983. Morphological variation in wing-moulting South African Shelducks.Ostrich54:19-25. Male and female South African ShelducksTadorna canalose 25,6 and 28,2% of their pre-moult weight during the flightless period. Juveniles (3–5 months old) do not take part in the wing-moult aggregation. Subadults (15–17 months old) cannot be distinguished from older birds in wing-moulting populations on the basis of the bursa of Fabricius, penis structure, colour of the wing feathers, foot colour and the size of the culmen and tarsus. It is suggested that the catabolism of body tissue during wing-moult has little effect on the survival of the species.

ISSN:0030-6525    

DOI:10.1080/00306525.1983.9634438

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

ISSN:0030-6525    

DOI:10.1080/00306525.1983.9634439

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Hockey, P. A. R. 1983. Aspects of the breeding biology of the African Black Oystercatcher.Ostrich54:26-35. Fifty-five pairs of African Black OystercatchersHaematopus moquinibred at Marcus Island in 1979–1980. Sixteen pairs laid replacement clutches: the mean interval between loss of the fist clutch and laying of a replacement clutch was 22,2 days. Mean inter-nest distance was 19,4 m. The modal clutch size was 2, with a mean of 1.74. Mean dimensions of 105 eggs were 60,7 × 40,l mm and mean fresh egg mass was 55,s g. There were differences in egg mass and dimensions between eggs in one- and two-egg clutches. Rate of egg loss was high, due mainly to depredation by Kelp GullsLarus dominicanuspromoted by human disturbance. Fledging success was lower at a disturbed site than at undisturbed sites, with highest chick mortality occurring in the first week of life. Mortality of first-year birds of eight days and older was estimated at 48% and 69% in two successive seasons. All juvenile birds dispersed from the natal sites, and were resighted up to 168 km away. Dispersed juveniles were concentrated at the edge of an area of high oystercatcher density.

ISSN:0030-6525    

DOI:10.1080/00306525.1983.9634440

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Earle, R. A. 1983. Foraging overlap and morphological similarity among some arboreal insectivorous birds in an Eastern Transvaal forest.Ostrich54:36-42.

ISSN:0030-6525    

DOI:10.1080/00306525.1983.9634441

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Dyer, Michael. 1983. Effect of nest helpers on growth of Redthroated Bee-eaters.Ostrich54:43-46. The effect of nest helpers on the growth of Redthroated beaters was studied at Samaru, northern Nigeria. Nestlings in broods raised by pairs with helpers grew heavier and faster than in those raised by unassisted pairs. The most significant improvements in growth were found in late-hatched nestlings of larger broods. Possible benefits of heavier and faster growth are considered in terms of prefledging development and postfledging survival.

ISSN:0030-6525    

DOI:10.1080/00306525.1983.9634442

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Hamed, D. M. & Evans, S. M. 1983. Breeding habits and nesting success of the Redcheeked Cordon-bleuOstrich54:41-49.

ISSN:0030-6525    

DOI:10.1080/00306525.1983.9634443

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

ISSN:0030-6525    

DOI:10.1080/00306525.1983.9634444

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

ISSN:0030-6525    

DOI:10.1080/00306525.1983.9634445

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

ISSN:0030-6525    

DOI:10.1080/00306525.1983.9634446

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor