摘要:

Moult data were collected during 1967–80 from some 6900 Little Stints in the southern Kenyan rift valley.Adults typically moulted from summer to winter body and head plumage during September and early October, soon after arrival. The complete pre‐winter wing and tail moult began in most adults between mid‐September and early October. Some birds finished by December, but others continued until February and March. Individual duration was usually between 100 and 150 days. Adults which completed this moult early often remoulted outer primaries between January and early April.Young birds acquired first‐winter body plumage during October and early November. Some 90% had a complete pre‐winter wing and tail moult. This usually began between December and early February, and finished during March or early April, taking about 70–100 days. In about 10% of young birds, flight feather moult was restricted to the outer primaries and inner secondaries. Birds adopting this strategy typically began moult late, during January or February. Short periods of suspension were common during pre‐winter wing moult, particularly in adults. The difference in moult speed between adult arid first‐winter birds was attributable in the primary, secondary and tail tracts to differences in numbers of growing feathers.Practically all birds completed a pre‐summer moult involving the entire body and head plumage, most of the tertials, some or all of the tail feathers and many wing coverts. Most birds began this moult between early February and late March, and finished between mid‐April and early May. It was typically later and more rapid in first‐year birds than adults. In late birds, the onset of pre‐summer moult was linked to the final stages of pre‐winter moult.The wing moult of the Little Stint in different wintering areas is discussed. First‐winter moult strategy is compared with that in

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1984.tb03659.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

A sophisticated radiotelemetry system was used to monitor continuously the temperature, relative humidity and the incidence of parental movement sufficient to admit light to, or turn the eggs in, the nest cup of (number of days recordings m parenthesis): Black SwanCygnus atratus(68); Barnacle GooseHrantal leucopsis(70); Whooper SwanCygnus cygnus(28) and Greylag GooseAnsev anser(26). The following features were common to all the nests: (1) a slow rise in the temperature of the nest cup with the onset of incuhation; (2) a temperature gradient in the vertical plane of the nest cup throughout incubation; (3) a diurnal rhythm in the temperature and humidity of the nest cup, this being caused by bird behaviour rather than the ambient environment; (4) nesting materials dried out during incubation thereby accentuating the steepness of the diffusion gradient between a real egg and the atmosphere of the nest cup; (5) the eggs, which were turned between 0.594.95 times an hour, were rotated mainly around their long axes.

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1984.tb03660.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

The number of spiders caught by caged Great TitsParus majorin a 10 minute test increased in a sigmoid fashion with ambient temperature between 2 and 13°C. In control tests with immobile preyCalliphorapupae there was no significant effect of temperature. These results indicate that increasing activity of arthropod prey with temperature (Kacelnik 1979b) renders them more vulnerable to predators. We suggest that one reason why small temperate‐zone birds such as Great Tits do not forage but sing when they get up in the morning is because low ambient temperatures reduce prey activity and hence the profitability of foragi

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1984.tb03661.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

In an area of south‐central England Mistle ThrushesTurdus viscivorusregularly defend fruit‐hearing plants (four kinds of tree, ivy and mistletoe) against intruders from autumn to early spring. HollyIlex aquifoliumis by far the most important of the plants defended. To be suitable for defence, a tree must be free‐standing and of moderate size. Observations were carried out over three winters, one mild, one very severe and one intermediate. During the mild winter hollies were successfully defended until the Mistle Thrushes gave up active defence with the onset of breeding activities. During the very severe winter nearly all defended hollies were overwhelmed by invading flocks of other thrush species during the very cold spells. Mistle Thrushes in possession of a fruit supply conserve it by feeding on undefended fruit near‐by if it is available, and to a large extent on the ground when conditions are suitable. Defended fruit trees are generally avoided by other species living in the vicinity. Hence depletion of fruit from defended trees is much slower than from undefended trees, and consequently the fruit may last for several months and provide a food supply in dry weather in spring and early summer for Mistle Thrushes and other species.Fieldfares and Blackbirds show similar, but less well developed, fruit‐guarding behaviour. Fruit‐defence is clearly related to the bird's size, but other physical and behavioural adaptations may be involved. The most important characteristic of holly fruit making it suitable for defence, apart from the dimensions and spatial relationship of the tree, is its ability to last for many months without significant de

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1984.tb03662.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Adult Blue Jays, Brown Thrashers, Northern Catbirds, American Robins, and Song Sparrows were offered fresh frozen and thawedBombus pennsylcanicusand its mimic,Mallota bautias, simultaneously withTenebrio rnolitorpupae. MealwormT. rnolitorlarvae were offered separately in pairs as controls. Most of the birds refused the model and mimic, but all of the Blue Jays and some of the Brown Thrashers had specialized feeding techniques to deal with the aposematic insects. These techniques and other feeding behaviours are described in detail. Beak wiping appeared to be a displacement behaviour in Song Sparrows and American Robins. Predator — prey relationships are discussed briefl

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1984.tb03663.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Information on the breeding biology of Neotropical swallows is scarce (Bent 1942, Ricklefs 1971, Ridgely 1976). The aim of this study was to determine some details of breeding biology of Neotropical swallows for comparison with temperate zone species.

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1984.tb03664.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Captive King Vultures were unable to find hidden food by smell: this species flies at high altitudes over forest, and it is suggested that they locate carcasses by watching the activities of theCathartesvultures below them.

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1984.tb03665.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1984.tb03666.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1984.tb03667.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1984.tb03668.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY