摘要:

SummaryBewick's Swans were identified individually at Slimbridge from 1968‐69 to 1975‐76, both within one winter and from one winter to the next, by bill markings or large numbered leg rings. Units, rather than individuals, were used for analysis, each unit being placed into one of two categories (New, Experienced), and into one of four classes (family, pair, single, yearling).The Experienced category arrived proportionally earlier, had fewer one‐day attendances, stayed longer, were absent less, and departed later than the New category. Experienced families were absent more than the other Experienced classes and, in the early part of the winter, left proportionally ahead of them. Arrivals of the New classes were at different rates: yearlings built up quickest, followed by singles, pairs and families. Families had more one‐day attendance than yearlings and singles, and pairs were absent more than the other classes. The departures of the New classes, except of families, were closely synchronised.The different behaviours of the classes which determine length of stay are discussed. The birds most likely to return were those with a long attendance in a previous

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1980.tb00883.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

SummaryThe avifauna of Tasmanian temperate rainforest consists of 21 species, more than hitherto reported. Eleven species are very common, six are common and a further four species that have large home ranges are uncommon. Other species occur occasionally or accidentally.The structure of the Tasmanian rainforest community was determined from measured overlaps in horizontal habitat selection, vegetation layer utilization and foraging site distribution. This demonstrates the existence of guilds, the members of which react more with each other than they do with members of other guilds. Niche differentiation is shown in each guild in the breeding season. However, adaptations enabling survival during the non‐breeding season may be important in the seasonal Tasmanian environmen

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1980.tb00884.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

SummaryForaging and breeding behaviour of Seychelles Sunbirds Nectarinia dussumieri was studied for a total of four months on six islands in the Seychelles.Birds obtained nectar from indigenous and introduced plants directly (inserting the bill into the corolla‐tube), perched or hovering, or indirectly (piercing the corolla). Direct methods were used in plants with corolla‐tubes less than 20 mm (the length of birds' bills) and indirect methods in most longer flowers. Flowers with longer corolla‐tubes appeared to be preferred. In feeding groups, birds fed more rapidly if not involved in aggressive interactions, which may reflect defence of feeding areas.Insects were taken from the foliage of indigenous and introduced trees, using a variety of techniques. Flycatching was most prevalent in small‐leaved species, and upright probing in large‐leaved species. In Calophyllum inophyllum, which held very high densities of insects, hovering was used only in saplings, while other methods were used in both mature trees and saplings.The percentage of nests that were active declined from September to December‐January, suggesting a peak of breeding during this period, the first part of the northwest monsoon season. Examination of live birds and museum skins showed that wing‐moult occurs chiefly from January‐May, but males on Praslin also moult in August‐September.Nests varied in conspicuousness, being best hidden on Mahé and Silhouette, the only islands with populations of Seychelles Kestrels Falco araea. Males contributed to the earliest stages of nest building, but all later building, as well as all incubation and most feeding of young was done by females. Both sexes defended the nest area against other birds, especially those attempting to steal nest material. Males advertized by song from prominent perches near nests; females also sang occasionally.Males are larger in most dimensions than females, but no inter‐island differences were found. The species may have evolved duller plumage and larger size than related species, but this remains uncertain without further evidence on its origins. The clutch of one egg only represents a reduction from the normal clutch size of loca

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1980.tb00885.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

SummaryIn the Caribbean lowlands of Costa Rica, rainfall is moderately seasonal, although even in the driest month over 100 mm of rain usually fall. Flowering of hummingbird food plants shows a peak in the dry season (February‐April) and another in the early wet season (July‐September), with a severe flower shortage at the end of the rains (November‐December). The dry season peak involves largely canopy epiphytes, the wet season peak large herbs of light gaps and edges and forest understory plants. This study examines the responses of the associated community of 22 species of hummingbirds (of which 13 breed, and 12 are common for at least parts of most years) to these spatial and temporal patterns of resource availability. Nearly all common breeding species show a peak of reproductive activity in the dry season, coinciding with the first flowering peak, followed by a discrete moulting season that coincides with the wet season peak of flowering. Of the three species with extended breeding seasons, the two species of hermit,Phaethornis, show moult‐breeding overlap to varying degrees on an individual basis. In a number of species moult and breeding appear antagonistic. The annual peak of body weight and fat deposits in all species occur during the second flowering peak, approximately corresponding to the moult. The annual minima of body weight and fat occur in the lean season and the breeding season respectively. The lack of concordance of these two possibly reflects the use of muscle protein as a nutrient source during the lean season. Several species show pronounced habitat shifts through the year, with the sexes sometimes occupying different microhabitats, especially during the dry season. At least five species show pronounced seasonal migrations, largely or entirely leaving La Selva for part of the year. Overall hummingbird numbers are greatest early in the rainy season, lowest in the lean season, with the non‐hermits (Trochilinae) showing a more pronounced annual cycle of numbers than the hermits (Phaethorninae). Comparisons with other tropical lowland hummingbird‐flower communities are made with respect to the roles of flowers as proximate and ultimate factors regulating the annual cycles and affecting the population biology o

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1980.tb00886.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1980.tb00887.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1980.tb00888.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1980.tb00889.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1980.tb00890.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1980.tb00891.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1980.tb00892.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY