摘要:

Summary..The theories which have been advanced to explain the origin of the various forms of distraction display are considered and found to be inadequate. It is suggested that distraction displays have arisen through the “displacement” of components from other behaviour contexts, particularly threat and epigamic display, which have become ritualized into new behaviour‐patterns with survival

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1949.tb02261.x

出版商:Blackwell Publishing Ltd    

年代:1949

数据来源: WILEY

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1949.tb02262.x

出版商:Blackwell Publishing Ltd    

年代:1949

数据来源: WILEY

摘要:

Summary.The birds of the Cocos‐Keeling Islands, in the Indian Ocean, are discussed in the light of specimens and data collected during a stay of eleven months in 1941. Seventeen species were found to be breeding. One of these was an indigenous land bird, four were land birds known to have been introduced, and the remainder were sea birds mostly confined to North Keeling. During this period examples of seventeen species of strays or visitors were taken, of which ten probably occur regularly though in small numbers, while the other seven are true vagrants. Eight of these birds have not so far been recorded from Christmas Island.Eleven birds listed from the islands by previous visitors were not present in 1941. Two of these were introduced but have failed to maintain themselves, and one,Egrctta garzetta nigripes, seems to be an occasional vagrant. The remaining eight records are all unsatisfactor

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1949.tb02263.x

出版商:Blackwell Publishing Ltd    

年代:1949

数据来源: WILEY

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1949.tb02264.x

出版商:Blackwell Publishing Ltd    

年代:1949

数据来源: WILEY

摘要:

Summary.1. At Amani, Tanganyika Territory, the Paradise Flycatchers use the softest moss for their nests and make them durable by oversewing the rim with cobweb. Sites are on the forest edge nearly always over water. Theree hours of observation were made at three nests in spells of about eight hours at a time.2. On the whole the males and females shared the care of the eggs and the young about equally, but there were wide differences in this respect from day to day3. The eggs were covered for over 90% of the observed time, and a high proportion of spells “on” were terminated by thc mate's arriving to take over. Duration of individual spells “on” varied up to two hours, but the favourite duration (nearly half of all the spells) was about 30–40 minutes. This applied both to spells “on” terminated by the initiative of the sitting bird and to those terminated by the arrival of the mate. The possibility suggests itself that an internal rhythm was operating, irrespective of whether a bird was on or off the nest. Nevertheless, out of 39 occasions (all short) when the eggs were uncovered through the sitter's departure without relief, the same bird returned on 18, which suggests that when off the nest both parents “keep an eye on it” and react to the situation “nest uncovered”.4. Brooding of the young amounted at first to nearly the same high percentage of time as the brooding o f the rggs, but was in much shorter spells. It stopped abruptly about the fifth day. others followed a parent.5. Each nestling of a brood of two in a nest received more food (largely butterflies) than each in two broods of three, 2.6‐5.4 feeds per hour compared with 14‐2.5 and 1.3‐1.8.6. Some of the young that wcre seen to fly left the nest in the absence of the parents, All left between dawn and noon. Nestling period about 11 days irrespective of

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1949.tb02265.x

出版商:Blackwell Publishing Ltd    

年代:1949

数据来源: WILEY

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1949.tb02266.x

出版商:Blackwell Publishing Ltd    

年代:1949

数据来源: WILEY

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1949.tb02267.x

出版商:Blackwell Publishing Ltd    

年代:1949

数据来源: WILEY

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1949.tb02268.x

出版商:Blackwell Publishing Ltd    

年代:1949

数据来源: WILEY

摘要:

Summary.Distraction displays of the Arctic SkuaStercorarius parasiticuswere studied in the Faeroe Islands in colonial nesters and a solitary pair. There are aggressive and passive forms.The aggressive flight against human intruders is common throughout the nesting cycle in the colony, but absent from the behaviour of solitary pairs. It is suggested that its development is correlated with an internal rhythm which requires a certain level of mutual stimulation not attainable by solitary or widely‐scattered pairs. A highly formalized version of the attacking flight was employed against a sheep, in which the pair showed a marked tendency to coordinate their movements.The lure display when eggs are fresh is markedly different from that employed nearer the hatching‐period and afterwards. A courtship posture appears as a substitute activity in the early period, but only in the presence of the mate.In the solitary pair development of the normal lure display was gradual, reaching its peak towards the hatching‐period: there is a marked tendency for the pair to perform together, deriving mutual stimulation. It is suggested that this factor is important in the colony, where several perform together in scattered groups, in ensuring the earlier development (and therefore increased survival value) of the lure display. The birds' movements emphasize contrasts in the plumage coloration, and therefore the pattern may have greater biological advantage for colonies of predominantly light‐phase birds in areas of fox predation.The various patterns are described, and also variations incorporating false‐brooding and drinking motions. The main components of the patterns are probably derived from the primitive food‐begging of the chick, and elaborated with actions from courts

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1949.tb02269.x

出版商:Blackwell Publishing Ltd    

年代:1949

数据来源: WILEY

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1949.tb02270.x

出版商:Blackwell Publishing Ltd    

年代:1949

数据来源: WILEY