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M. P. Harris 《Ibis》1966,108(1):17-33
Studies on the breeding biology of Puffinus puffinus were carried out in 1963 and 1964 at the large colony on Skokholm, Wales. During the six weeks before laying the birds spent up to a quarter of the days in the burrows, but the ten days immediately prior to laying were normally spent at sea. There is a prolonged laying period, with a marked peak in the first half of May. Details are given of a second egg being laid when the first was deserted immediately after being laid. The male took the first incubation spell. The incubation spells ranged from one to 26 days and averaged six. The incubation period was about 51 days. The frequency of visits to land by breeding birds, unlike those by non-breeders, was not affected by the moon. On hatching, the chicks grew rapidly and reached maximum weights of between 505 and 755 gm. sometime between 39 and 61 days. There was a variable desertion period, usually eight or nine days, before the chicks left the island about 70 days after hatching. During the feeding period the chick received about two feeds every three days. There is evidence that adults visited the chicks more frequently than this. There was no correlation between growth of the chicks, their feeding rates or fledging weights and the time of laying. There was a high survival (about 95 %) of chicks during the fledging period but some eggs were lost in disputes for burrows. Nine pairs in 1964 were unable to raise two young simultaneously. Parents altered their feeding rhythms to try to feed two young but did not themselves lose weight. It is suggested that the critical factor in the production of young is the availability of food for the young immediately after they leave the colonies.  相似文献   

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The distribution and behavior of mature (12.3–16.3 m) male sperm whales ( Physeter macrocephalus ) were studied on the Galápagos Islands breeding ground from April to June 1995. In contrast to previous research seasons when males were observed only in close spatial and temporal proximity to mixed schools of females and immature animals, in 1995 males were sighted in loose aggregations, separated by hours to days from our vessel's encounters with mixed schools. Only one of ten identified males was observed in spatial proximity to a mixed school.
Aggregations consisted of two to four (minimum estimates) mature males travelling within a range of a few kilometers and were characterized by consistency of heading among individuals. Aggregations moved over time. During encounters, one to three males were observed at the surface at the same time, with interindividual distances of less than 1,000 m. Synchrony of heading was apparent between spatial associates, and its extent appeared to be related to interindividual distance. Clustering (two or more individuals within 100 m) was observed on only two occasions. No agonistic behaviors were seen.
Functions of mature male aggregation on a breeding ground remain unclear. Possible explanations for our observations are local prey abundance, or some form of sociality mediated over spatial scales of hundreds to thousands of meters.  相似文献   

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The breeding strategies of 52 Galápagos Islands angiosperms from 30 families were examined. Controlled pollinations were performed to determine if self-incompatiblity was more prevalent than previously thought, thus acting as an enforcer of outcrossing, or if instead, both dioecism and self-incompatibility are poorly represented and self-compatibility is the rule. The plants tested were located in each of the seven major vegetation zones on the southern slope of Isla Santa Cruz. Fruit and seed yields were compared between tagged but uncovered flowers (controls) and others that were subjected to various manipulations. Of the 52 species studied, one was dioecious, 11 yielded inconclusive results, and the remaining 40 showed self-compatibility. All but three of the latter group also demonstrated automatic self-pollination. This study suggests that on the Galápagos Islands hermaphroditic and dioecious plants occur in relatively the same proportions as found in their mainland source areas. Of the two hermaphroditic breeding strategies considered in this study, self-compatibility and self-incompatibility, the former is highly represented in the Galápagos flora.  相似文献   

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C. St. C. Robinson 《Ostrich》2013,84(3):153-158
Counting Saddle-billed Storks in a study area the size of the Kruger National Park, at 2.2 million ha, is difficult because the birds are long-lived, sparse in the landscape and have large home ranges. Aerial surveys conducted to date provide an estimate with no measure of data dispersion, thence precision. The aim of this study was to estimate the population size within associated confidence limits using a modified mark–recapture field method. The vehicle survey, conducted shortly after rainfall in the area, did not produce results with known precision under these conditions. A repeat of this census in spring, after the peak breeding season and when surface water is confined to the larger rivers and dams, should yield different results. A photographic census technique yielded sufficient information to construct a population registration database. Individual identification profiles indicate that there are at least 40 adult Saddle-billed Storks in the southern part of the Kruger National Park. This is considered the minimum number of known-to-be-alive individuals in this area. In this paper, the Cormack–Jolly–Seber mark– recapture model was used to return an estimate of the population size for each capture occasion.  相似文献   

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白额鹱卵壳的扫描电镜观察   总被引:9,自引:2,他引:9  
本文报道白额鹱卵壳的壳膜、孔锥层、海绵层、表层等的超微结构,并对卵壳元素进行TN-5500能谱分析。  相似文献   

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Mrs. J. A. Scott 《Ostrich》2013,84(3):201-207
Scott, J. A. 1975. Observations on the breeding of the Woollynecked Stork. Ostrich 46: 201–207.

Little is known about the breeding of the Woollynecked Stork Ciconia episcopus in Africa. This paper discusses breeding, adult and nestling behaviour, nests and sites. Seasonal movements are discussed briefly. Eight nests were studied during 1970 to 1974. At one nest incubation was established at 30 to 31 days and the fledging period 55 to 65 days. No feeding of the young was observed at any time, though one eight hour observation period was undertaken. Few mating displays were seen and none away from the nest.  相似文献   

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J. H. Phillips 《Ibis》1963,105(3):340-353
The breeding distribution of the Sooty Shearwater and the dates of its breeding season are briefly reviewed.
Records from the Southern Ocean are summarised. It is concluded that they are accounted for by non-breeding birds feeding off the ice-edge in the Australian sector of the Antarctic during the latter part of the breeding season.
The great majority of Sooty Shearwaters spend the southern winter in the Pacific Ocean. Birds from the New Zealand colonies are probably mostly found on the feeding grounds off Japan: some may make a "circular" migration around the Pacific. Birds from the Cape Horn colonies spend the southern winter in the rich areas off the western coast of North America.
Some Sooty Shearwaters spend the southern winter off the South African coasts. A number of non-breeding birds remain there throughout the summer.
The Sooty Shearwaters "wintering" in the North Atlantic are probably numbered in tens of thousands only. The distribution of records is reviewed month by month and the records from Atlantic transects are summarised. The migrations in the North Atlantic are discussed in relation to prevailing meteorological and oceanographic conditions, and food supply. It is concluded that most Sooty Shearwaters in the North Atlantic make a "circular" migration, crossing the North Atlantic from west to east in June and July, and re-crossing about September further south in the northeast trades.  相似文献   

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黄腹角雉的繁殖生态研究   总被引:17,自引:0,他引:17  
报道了黄腹角雉(Tragopan caboti)的典型栖地、种群密度、配偶、求偶炫耀、巢与卵的特征、觅食区及雌鸟孵卵行为。为在原产地对野生种群繁殖习性的首次系统记述。  相似文献   

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