共查询到20条相似文献,搜索用时 15 毫秒
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L. G. Grimes 《Ibis》1974,116(2):165-171
During the northern spring of 1970 and 1971, wader departures were tracked by radar from saltpans on the coast of Ghana near Accra. All but one of the departures headed northeast, and none were directed along the coast. There was a statistically significant difference between the mean heading of April departures (28°± 10°), and May and June departures (41°± 14°). Projected on great circles, all headings were directed towards the known breeding ranges of the wader species wintering at the saltpans.
In ten species, the dates of the first returning birds to the saltpans in 1966, 1968 and 1970 were about three weeks earlier than dates recorded in Senegal. It is likely that those reaching Senegal follow a coastal route, whereas waders wintering at the coast of Ghana and eastwards to Nigeria evidently make a crossing of the Sahara both in autumn and spring. 相似文献
In ten species, the dates of the first returning birds to the saltpans in 1966, 1968 and 1970 were about three weeks earlier than dates recorded in Senegal. It is likely that those reaching Senegal follow a coastal route, whereas waders wintering at the coast of Ghana and eastwards to Nigeria evidently make a crossing of the Sahara both in autumn and spring. 相似文献
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Cooper, J. 1975. Primary moult, weight and breeding cycles of the Rock Pigeon on Dassen Island. Ostrich 46:154-156. The primary moult season of the adult Rock Pigeon Columba guinea on Dassen Island is spread over at least nine months. Individual duration is estimated at eight months. Adult birds were heaviest in the winter months outside the breeding season. Overlap between the breeding and moulting seasons occurred and evidence was obtained of incubating birds with active primary moult. Juveniles were lighter than adults. Adults fed on the mainland and probably made daily flights there. 相似文献
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K. D. Smith 《Ibis》1965,107(4):493-526
Fifteen months were spent in Morocco. A few ecological aspects of the country are described, together with their influence on the dispersal of birds in winter. Some winter visitors are listed and discussed, several species were much commoner in the winter of 1962/63 than in 1963/64, in some cases presumably as a result of the cold weather in Europe, although in others not obviously so. Cold-weather movements of gulls, Lapwings and Cranes were observed. Individuals of species that are normally trans-Saharan migrants winter in Morocco in small numbers. Spring migration in southeast Morocco is excluded from discussion, but autumn migration in western Morocco is summarized and compared with existing data. The systematic list is devoted largely to winter visitors and passage migrants, but resident species are listed when new localities, breeding data or field notes warrant their inclusion. Six species not hitherto recorded in Morocco, were seen. 相似文献
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Russell G. Rhodes 《Journal of phycology》1972,8(1):117-119
Porterinema fluviatile (Porter) Waern has been found, as a microscopic filament on a culm of Spartina from a tidal marsh on the Atlantic coast of Virginia. This represents the first report for Porterinema from a marine site in North, America. 相似文献
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Schmitt. M. B. & Whitehouse, P. J. 1976. Moult and mensural data of Ruff on the Witwatersrand. Ostrich 47: 179–190 During a five-and-a-half year study 1 600 Ruffs Philomachus pugnux were captured on the southern and eastern Witwatersrand, South Africa. Mensural data for these birds are given and the moult cycle discussed. Birds in the study area appear to moult much later than elsewhere, but the moulting sequence appears similar. Recaptures and leg colour are discussed. 相似文献
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A new species of Haminaea from the Southern Iberian Peninsulais described. Haminaea templadoi is characterized by the presenceof a penis with an apical semispherical crest provided by tensmall transverse folds and a well developed lateral lobe. Theshell has a sculptured surface with growth lines crossed bysmall transverse folds. (Received 20 October 1990; accepted 24 January 1991) 相似文献
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褐马鸡雏鸟的换羽研究 总被引:1,自引:0,他引:1
对我国特产珍禽——褐马鸡雏鸟的羽毛生长及脱换即“稚后换羽”进行了观察研究。褐马鸡有小翼羽4枚,初级飞羽10枚,次级飞羽13枚,三级飞羽4枚,尾羽22枚。稚后换羽是飞羽和尾羽全部脱换,仅第一枚初级飞羽当年保留。 褐马鸡羽毛的脱换规律是:飞羽是先生长者先脱换;尾羽是由外向内的“向心型”。 相似文献
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THE MOULT OF THE BULLFINCH PYRRHULA PYRRHULA 总被引:1,自引:0,他引:1
The distribution of feather tracts and their sequence of moult in the Bullfinch is described. The adult post-nuptial moult, which is complete, lasted 10–12 weeks, and the post-juvenile moult, which is partial, 7–9 weeks. Adult moult began with the shedding of the first (innermost) primary and ended with the replacement of the last. Variations in the rate of moult in the flight feathers were mainly achieved, not by changes in the growth rates of individual feathers, but in the number of feathers growing concurrently. The primaries were shed more slowly, and the onset of body moult delayed, in birds which were still feeding late young. In 1962, the onset of moult in the adults was spread over 11 weeks from thc end of July to the beginning of October, and in the two following years over the six weeks, from the end of July to the beginning of September. The onset of moult was delayed by late breeding, which itself occurred in response to a comparative abundance of food in late summer, markedly in 1962. In all years, the first juveniles to moult started at the end of July, and the last, three weeks after the latest adults. Juveniles moulting late in the season retained more juvenile feathers than those moulting earlier. During moult, adult and juvenile Bullfinches produce feathers equivalent to 40% and 33% respectively of their dry weights. In both, for much of the moult, an average of nearly 40 mgm. of feather material—some 0.6% of their dry-weight–is laid down each day. The remiges of the adult comprise only a seventh of the weight of the entire plumage, and it is suggested that their protracted moult results not so much from their energy requirements, as from the need to maintain efficient flight. Variation in the rate of moult in the remiges was much less pronounced than in the body feathers. Bullfinches were less active during moult than at other times of the year. The weights of both adults and juveniles increased during moult. The food during the moult period is described. In all years, most Bullfinches finished moulting just before food became scarce, even though this occurred at different times in different years. In one year, adults moulting latest in the season probably survived less well than those moulting earlier; the same was apparently true of the juveniles in all years. The timing of moult in the Bullfinch, and the factors initiating it, are discussed in relation to the breeding season and foodsupply near Oxford. 相似文献
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