首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
C. J. Vernon 《Ostrich》2013,84(2-3):89-94
Vernon, C. J. 1976. Eighteenth ringing report for southern Africa. Ostrich 47:89-94. A report on ringing activities in southern Africa from July 1974 to June 1975 is presented. A total of 47 777 birds of 475 species were ringed. This information is examined according to distribution of ringers, species ringed and recovery rates.  相似文献   

2.
C. J. Vernon 《Ostrich》2013,84(3-4):106-109
Vernon, C. J. 1977. Nineteenth ringing report for southern Africa. Ostrich 48:106-109. A report on ringing activities for southern Africa from July 1975 to June 1976 is presented. A total of 36 016 birds of 419 species was ringed. The trends follow the general decline in ringing activities sinze a peak in 1970/71.  相似文献   

3.
4.
E. H. Ashton 《Ostrich》2013,84(2):106-112
Craig, A.J.F.K. &; Hulley, P.E. 1994. Sunbird movements: a review, with possible models. Ostrich 65: 106–110.

Based on current fieldwork, we propose four possible models to explain the winter influx of sunbirds which we have observed: the birds may be (1) “winter residents”, which move annually to a wintering area and remain there; (2) “shoppers”, which periodically investigate feeding areas within their home range and feed opportunistically where nectar is most abundant; (3) “tourists”, which successively visit a series of sites on a regular itinerary; (4) “nomads”, which move unpredictably to new areas whenever food supplies decline. and have no home base. Current data on sunbird movements are reviewed, and in a few cases the winter resident model is unlikely, but generally it is not yet possible to eliminate any of the hypotheses. Moult cycles based on both field and museum studies may provide additional information, as movements are unlikely while active wing-moult is in progress; some species show interrupted wing-moult, which may be associated with long-distance flights.  相似文献   

5.
6.
J. W. H. WILSON 《Ostrich》2013,84(2):108-111
Steyn, P. &; Grobler, J. H. 1981. Breeding biology of the Booted Eagle in South Africa. Ostrich 52:108-118.

The Booted Eagle Hieraaetus pennatus is a breeding visitor to the Cape Province of South Africa, wintering mostly in Namibia on present knowledge. Palaearctic birds probably also reach the Cape but arrive later. Two nests in different localities in the Cape were studied. The birds breed soon after arrival. Both sexes build the nest on a cliff ledge. Incubation, which lasts 40 days, is done mostly by the female. The female spends most of her time on the nest during the first four weeks of the nestling period, but considerably less time thereafter. The male provides nearly all the prey until near the end of the nestling period, and helps to feed the young. Details of nestling growth and behaviour and of parental care are given. The nestling period was 50 and 54 days in two cases. Post-nestling dependence is about two months. Prey preferences in the two study areas were very similar: 54% birds, 33% lizards and 13% rodents. Breeding biology in South Africa is basically the same as that of Palaearctic populations, with the main differences being the habitat and cliff nest site.  相似文献   

7.
8.
A. C. Kemp  J. C. Snelling 《Ostrich》2013,84(3-4):154-162
Kemp, A. C. & Snelling, J. C. 1973. Ecology of the Gabar Goshawk in southern Africa. Ostrich 44:154-162.

Observations on the plumage types, moult and general ecology of the Gabar Goshawk Melierax gabar are considered, and special attention is given to the hunting behaviour and prey of this species. The habit of nest-robbing is particularly important.  相似文献   

9.
Badenhuizen , N. P. (U. Toronto, Ont., Can.), and E. N. Lawson . Lethal synthesis in Cynodon dactylon growing in southern Africa. Amer. Jour. Bot. 49 (2) : 158–167. Illus. 1962.—Both cultivated and wild forms of Cynodon dactylon are characterized in southern Africa by the random production of chlorotic shoots. Some properties of these shoots were typical of chlorotic shoots in general: increase in water and soluble nitrogen content, and inhibition of protein synthesis, chloroplast development and catalase activity. Others, such as sterility and enhanced respiratory activity, were more characteristic of plants treated with streptomycin or amitrol. Allantoin could be demonstrated in the chlorotic shoots and was found to produce chlorosis after being applied to Cynodon plants. Additional characteristics included decreased total and “active” iron content, accompanied by an increase in citric acid. So far, the weight of evidence, including the ultrastructure of the plastids, is not in favor of a mutation, a virus, a fungus, or iron deficiency as the ultimate cause of chlorosis in Cynodon. There appears to be a tendency towards the production of allantoin which may be triggered off more frequently under certain conditions of environment, until a concentration is reached when it irreversibly inhibits stages in the development of the chloroplasts.  相似文献   

10.
SUMMARY

The length mass relationship for a Labeo capensis population is described by the equation M = 0,0134 L2'999 where 2,999 represents a constant the value of which indicates isometric growth. There is very little difference between the length/mass relationship for males and that for females and this is similar to the results found by Mulder (1973) for L. capensis in the Vaal River. The length/mass relationships for gravid males and females are different from that of the population as a whole indicating that maturity does result in a change of the body form which is in accordance with the results of Mulder (1973).

A modified formula to take into account, small length intervals of an age group, is used to calculate the relative condition factor for Labeo capensis from the Caledon River for a consecutive “winter” and “summer” period. The results show that the conhd1t10ni for Labeo capensis of the 0+, 1+ and 2+ age groups is better in the summer period than in the winter period, whereas in the older age groups 3+ to 5+ the condition in winter is better than in summer. This can be attributed to the attainment of sexual maturity at the age of 3+ years and the presence of large quantities of fat deposited in the body during the winter months, which are then utilised for the development of the gonads prior to spawning. These results are similar to those obtained for the same species by Mulder (1973) in the Vaal River and by Bloemhof (1974) in the Hardap Dam.  相似文献   

11.
12.
PRELIMINARY REPORT OF AMPHIBIA FROM SOUTHERN YUNNAN   总被引:1,自引:0,他引:1  
The specimens for the present study were collected in 1957 from Sze-mao, Pou-wen, Meng-yang, Yun-ching-hung and Meng-hai, by Academia Sinica and the Biology Departments of Sze-chwan University and Yunnan Universidy. Thirty-two species belonging to 13 genera, 8 familiesand 2 orders were obtained: 11 old provincial records, 10 new provincial records (including a new  相似文献   

13.
14.
15.
16.
Peter Steyn  J. H. Grobler 《Ostrich》2013,84(1-3):151-156
Steyn, P. & Grobler, J. H. 1985. Supplementary observations on the breeding biology of the Booted Eagle in Southern Africa. Ostrich 56:151-156

Further observations on the biology of the Booted Eagle Hieraaetus pennatus in southern Africa are presented. Several nest sites in trees are described, and details of behaviour during the incubation and early nestling period are given. The down colour of nestlings is discussed. One juvenile returned to its natal area the following breeding season. In ninepair-years the replacement rate was 1,0 young/pair/year. Prey records confirm that birds predominate. The implications of the recent discovery of breeding in mid-winter in Namibia are discussed; there may be three Booted Eagle populations in southern Africa.  相似文献   

17.
SUMMARY

Five new Arrenurus spp, from Southern Africa are described: A. amoenus sp. nov. from Natal, A. agnewi sp. nov., A. curtipalpus sp. nov., A. pedatus sp. nov. and A. cavatus sp. nov. from Botswana. The species from Natal came from an older collection belonging to the National Institute for Water Research. The species from Botswana were collected recently by Dr J.D. Agnew1

The water mite fauna of South Africa is only partly known. Therefore it is important that collectors should know that alcohol and formalin are not suitable fixatives. Fixing and storing is most successful in the following mixture: 5 parts glycerin, 2 parts glacial acetic acid and 3 parts water.  相似文献   

18.
Changes in gonadal histology were used to determine the reproductivecycles of three trochid gastropods commonly found along theTranskei coast. They were dioecious, the sexes being evenlydistributed both in terms of numbers and size. Despite someasynchrony, Monodonta australis had a distinct reproductivecycle with a short inactive period during the winter, gonadaldevelopment coincided with increasing sea temperatures and spawningtook place from late summer to autumn. Both Oxystele tabularisand O. variegata exhibited asynchronous intermittent spawningthroughout the study period. However, intensified spawning activityby O. tabularis was noted between April and September. The reproductivecycles and mechanisms of these trochids are compared with thoseelsewhere. (Received 20 January 1986;  相似文献   

19.
《Ibis》1952,94(1):128-132
Trapping and ringing of non–resident birds in Egypt in 1949 and 1950 are recorded and details of re–trapping after migration and of one foreign recovery are given.  相似文献   

20.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号