摘要:

Summary.1In autumn in Norfolk, the main nocturnal departures are (i) S.S.E., especially in September, of British summer residents; (ii) E., of unknown species; (iii, iv) S.S.W. and W., chiefly in October, the onward passage of birds, mainly thrushes, arriving in these directions from over the sea. Rarely, there are small northward movements. The main diurnal departures are (i) S.E., chiefly from mid‐September to mid‐October, of British summer residents; (ii) W., chiefly in October, the onward passage of diurnal migrants from Holland.2The main immigrations are (i) S.S.W. from Norway, chiefly of chats, warblers, flycatchers and arctic waders in September, and of thrushes in October; (ii) S.S.E. from northern Britain, chiefly in September, of British summer resident night‐migrants drifted off‐shore by westerly winds; (iii) W. by both day and night from Holland, mainly of Lapwings and small night‐migrants in September and of Starlings, Chaffinches, thrushes and Lapwings in October; (iv) both nocturnal and diurnal migrants heading W.S.W. from Denmark, when drifted south by northerly winds, of the same species as in (iii).3All 9 nocturnal and 4 diurnal movements analysed were far commoner and denser with following than opposed winds. They occurred with cross and opposed winds mainly when the wind was light. They tended to be commoner in clear than cloudy weather, and in anticyclonic than disturbed weather. After allowing for wind‐direction, they were equally common in warm and cold weather.4Small passerine night‐migrants leaving England S.S.E. must change their heading to southwest somewhere around the south of France. Arctic waders arriving S.S.W. must have changed their heading in Scandinavia from one much further to the west.5Norwegian thrushes change their heading from S.S.W. to S.S.E. when over the sea after dawn, provided that they have also been drifted by easterly winds, but they change back to S.S.W.

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1963.tb02473.x

出版商:Blackwell Publishing Ltd    

年代:1963

数据来源: WILEY

摘要:

Summary.The food and feeding habits of Tufted DuckAythya fuligulaare described, based on field observations and on the analyses of the stomach contents of 95 birds, all but one of them having fed inland; 57 were collected from a gravel pit near London, 28 from Northern Ireland and 9 from a number of English inland waters, in the shooting seasons 1959‐60 and 1960‐61.The London birds in both seasons had fed primarily on molluscs, mainlyDreissena polymorpha.The Northern Ireland birds, whereD. polymorphadoes not occur, had a more variable diet, again mainly molluscs, but with some crustaceans, insects and plant seeds. The English birds had a similarly variable diet with the emphasis on crustaceans (Asellusspp.) and with some molluscs, insects and plant seeds. Brief information is given on the food of young birds.It is suggested that the spread ofD. polymorphamay be one of the factors explaining the recent spread of the Tufted Duck in certain areas. It appears that where one particular food such asD. polymorphais not plentiful a more variable diet is taken, though molluscs always figure prominently. The type of food taken depends on the type of habitat used, the availability and size of the food items and on the methods of feed

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1963.tb02474.x

出版商:Blackwell Publishing Ltd    

年代:1963

数据来源: WILEY

摘要:

Summary.Willow WarblersPhylloscopus trochilusat Wytham, Oxford (51° 46' N., 1° 15' W.), start to sing around sunrise, in late April to early June. In the continuous daylight at Neiden, East Finnmark (69° 42' N., 29° 25' E.), they do not sing all the time, but in late June to late July start singing between 22.45 and 01.45 hrs., the start becoming progressively later as the season draws on. At Neiden, nest visits start some time after song (01.00–02.30), and this is probably also true at Wytham.The influence of environmental variables on the starts of the two cycles is discussed. It is concluded that song starts at Wytham when light intensity has risen above a certain threshold level, and at Neiden, when it has reached a minimum value or has started to rise again. It is suggested that the Neiden birds react to the closest approximation of their light intensity cycle to that at dawn further south. The end of daily song at Neiden may be controlled by internal factors. It is suggested that the start of the Neiden nest‐visit cycle is controlled by light intensity, but modified by temperature effects. The possibility that the environment affects the bird indirectly, via its brood or food, can be ruled out. The functional significance of the retention of activity lulls in the continuous daylight of the Arctic summer is discussed.The daily song‐starts of the Garden WarblerSylvia borin, BramblingFringilla montifringilla, and YellowhammerEmberiza citrinella, follow the same pattern as those of the Willow Warbler. The RedwingTurdus musicusoften has no daily song lull; its nest‐visit lull begins and ends well before midnight. The significance of this i

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1963.tb02475.x

出版商:Blackwell Publishing Ltd    

年代:1963

数据来源: WILEY

摘要:

Summary.Part 1.Some action patterns of the Magpie Goose are clearly ritualized as signal actions, whilst others, although not so ritualized, are none the less characteristic of particular moods of the bird. It is considered that the action patterns form a simple language such that individual geese are aware and can often anticipate the actions of other geese.Particular attention is given to fighting actions, which appear on the second day of a goose's life, and to “concerting”, at first a threat display but later also used in pair maintenance, where it appears very similar in function to the triumph display of true geese.Part 2.The family, comprising the reproductive group and its offspring, is the fundamental entity in Magpie Goose flocks. Males may be paired to one or two females, but they dominate their mates and offspring and defend a “territory” around them from other geese.Magpie Goose flocks are built up of families, each of which acts independently except in an alarm situation, when the flock acts as an entity. Flocks build up at feeding, roosting and watering sites, and although constant in location are probably composed of a different combination of families each day. The flock behaviour of Magpie Geese closely parallels that of the true geese.No alarm stimuli have been found which are innately recognized by Magpie Geese. The fact that alarm stimuli are learnt, taken with the unstable nature of the flocks, suggests that it may be very difficult to produce a “magic wand” which effectively scares the birds from

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1963.tb02476.x

出版商:Blackwell Publishing Ltd    

年代:1963

数据来源: WILEY

摘要:

Summary.Under dietary conditions that experimentally prevented the accumulation of “pre‐migratory” depot fat, typical nocturnal migratory restlessness developed in the BramblingFringilla montifringilla.Subsidiary data are presented fromJunco hyemalisandZonotrichia albicollis.In captive controls, the rapid accumulation and subsequent utilization of body fat closely paralleled the onset and waning of nocturnal unrest.Although the Brambling accumulates fat reserves before both nuptial and contra‐nuptial flights, it would seem that the presence of such is not an essential element of the so‐called “total physiological state” necessary for the onset

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1963.tb02477.x

出版商:Blackwell Publishing Ltd    

年代:1963

数据来源: WILEY

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1963.tb02478.x

出版商:Blackwell Publishing Ltd    

年代:1963

数据来源: WILEY

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1963.tb02479.x

出版商:Blackwell Publishing Ltd    

年代:1963

数据来源: WILEY

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1963.tb02480.x

出版商:Blackwell Publishing Ltd    

年代:1963

数据来源: WILEY

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1963.tb02481.x

出版商:Blackwell Publishing Ltd    

年代:1963

数据来源: WILEY

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1963.tb02482.x

出版商:Blackwell Publishing Ltd    

年代:1963

数据来源: WILEY