摘要:

SummaryThe breeding community of petrels on the Chatham Islands has previously seemed curiously poor compared to that of analogous stations in the Indian Ocean or South Atlantic (14 species compared with 18 in the Tristan‐Gough group). Examination of subfossil deposits from the Chatham Islands probably dating from the early stages of human colonization which occurred within the last few hundred years reveals remains of at least 20 petrels, all of which except one may well have bred in the past, without including storm petrels, of which two species are still known to breed while others may also have bred in the past. The grand total of at least 21 breeding species, many apparently in vast numbers, would probably make the archipelago the most important breeding station for petrels in the world at the time of the first human colonization. It seems possible that in addition to the present breeding species the following may have bred: at least one endemic species of gadfly petrel, the Magenta PetrelPterodroma magentae, and local populations of at least two other gadfly petrels, two shearwaters of the genusProcellariaand two of the genusPuffinusand a sooty albatross of the genusPhoebetria. Small populations of these, and perhaps other undetected species as well, may still survive in inaccessible place

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1967.tb00001.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

SummaryStomach contents of 34 Purple MartinsProgne subisand 90 netted samples of flying insects were analysed taxonomically and quantitatively and compared with one another. Insect food sources tend to become more abundant, taxonomically variable, and larger in size late in the season (August). Maximal availability of food thus coincides with maximal energy requirements of Purple. Martins, which then are at peak numbers, initiating moult, accumulating fat and beginning migration.

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1967.tb00002.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1967.tb00003.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

SummaryHamerkops were studied in Uganda, mainly in the vicinity of Kampala, during January‐August 1964. Behavioural observations were made of nest‐building pairs, as well as of non‐breeding birds.Locomotion and feeding behaviour are described. Diving take‐offs and landings, essential for entering or leaving a completed nest, are sometimes seen in other situations as well. Birds sometimes forage while on the wing, in addition to the more usual method while wading.The most frequently seen comfort movements and maintenance activities are described. Hamerkops do not excrete onto their legs when over‐heated as do the storks. The resting posture of sitting completely down on horizontal branches, which is common among Hamerkops, apparently is not known in any of the herons or storks.Primarily hostile (Upright and Forward Threat) and primarily sexual (“Yip‐purr”, Nodding and False Mounting) social displays are described. During False Mounting, birds mount their partners repeatedly without making any attempt at copulation; reverse mountings, in which the other partner assumes the top position, are frequent.The large, hollow nest and its construction are briefly described. During the 6–7 week building period at one nest, at least 8000 loads of material were added to the structure. Both members have an equal role in nest‐building, and generally work independently of each other. They showed no stick‐exchange displays as do herons and storks.When all known aspects of the Hamerkop's behaviour are considered, there appears to be little similarity with either the herons or the storks. In fact, present behavioural evidence does not seem to indicate a particularly close relationship with any other

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1967.tb00004.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

SummaryThe habitats and foods of ten species of finches studied near Oxford, England, are described in detail, and differences in feeding habits between them are related to differences in bill‐ and leg‐structure, body‐weight and behaviour. The Hawfinch, Siskin, Redpoll and Crossbill live primarily in woodland, the Greenfinch, Linnet and Goldfinch primarily in farmland, while the Bullfinch and Chaffinch breed, and occur throughout the year, in both these habitats. Habitat differences between species were probably more marked in primeval England than now, and the problems of studying animals in man‐modified environments are discussed in this context.Diet was studied by observation and by gut‐analyses of live and dead finches. Before roosting, finches usually accumulate food in their gullet, which is expandable but otherwise undifferentiated (the term “crop” is thus inappropriate). The Lesser Redpoll, the smallest species studied, can store up to about 0.8 c.c. of food in its gullet, but the Greenfinch, one of the largest finches, up to 2.5 c.c. Among theCarduelisfinches, the Greenfinch lives mainly on the large seeds of various trees, cereal crops and agricultural weeds; the Goldfinch on the seeds of Compositae; the Siskin on alder and conifer seeds; the Lesser Redpoll on birch and other small seeds; and the Linnet on the seeds of various weeds of farmland. The Hawfinch and Bullfinch eat a greater proportion of buds and seeds from fleshy fruits than do other finches; but the Hawfinch prefers larger ones than does the Bullfinch. The three European crossbills feed almost entirely on conifer seeds; specializing on different tree species. In summer, the Chaffinch and Brambling live largely on invertebrates but in winter on beechmast or small seeds taken from the ground. In winter, Chaffinches reaching Britain from northern Europe tend to feed in large flocks in open areas and to roost communally, while residents tend to remain near their breeding places and roost singly.The migrations and distribution of finches in Europe are described briefly. At any time of winter, closely related species with similar feeding habits are often concentrated in different parts of a common wintering range. Furthermore, in some species, such as the Goldfinch and Chaffinch, the sexes winter mainly in different areas.In Oxford, food was least readily available during hard (winter) weather and there was then complete segregation in diet between different species, but at other times their diets often overlapped considerably. The overlap was much more pronounced in the species living in farmland (which is an artificial habitat) than in those living in natural or seminatural woodland; some tentative explanations for this are offered.The fringilline finches, the Chaffinch and Brambling, feed their young entirely on invertebrates, are territorial in the breeding season and collect food mostly within their territories. The cardueline finches, on the other hand, feed their young mainly, or entirely, on seeds, often nest in “loose colonies” and usually gather food communally at some distance from their nests. The fringilline finches carry food in their bills to the young, which therefore receive small, but frequent, meals; whereas the carduelines feed their young by regurgitation and at longer intervals. Among the carduelines, the Hawfinch is exceptional in that seeds are first swallowed and regurgitated to the nestlings, whereas insects are carried in the bill. The Bullfinch develops in the breeding season special buccal pouches in which food is carried to the young. In general, most finches select diets for their young which differ from their own diets in the breeding season. The Crossbill and Linnet often feed their young on seeds alone, and some other species may do so occasionally. The breeding of these carduelines is therefore independent of a supply of invertebrates, but always coincides with an abundance of seeds. They breed at seasons when other birds do not; the most extreme cases are the three crossbills, which, given an abundance of suitable seeds, will nest at any time of year.The process of seed‐husking is described; the strength of the jaws, the extent of the gape and the width of the palatal grooves limit the size and hardness of seeds which a given species can take. No two species have bills of the same shape and size, and differences in diet between species are connected with differences in the structure of their bills and the way the bill is used. In general, the deeper the bill of a finch, the more numerous the types of seeds in its diet.The Greenfinch, Linnet and Redpoll have relatively short broad bills and feed more than do otherCarduelisfinches from plants whose seeds are relatively exposed (e.g. grasses) or enclosed within pods or capsules; they also pick up many fallen seeds from the ground, but each species concentrates on different sizes of seeds. The Goldfinch and Siskin have reIatively long, narrow bills and obtain much of their food by probing into cones and into the seed‐heads of Com‐positae; unlike other finches, they also use a gaping movement while feeding. The Goldfinch has a longer bill and eats more Compositae seeds than the Siskin, while tlie latter eats more tree seeds than the Goldfinch. Further, male Goldfinches have slightly longer beaks than females, and hence can obtain teasel seeds more efficiently; females feed only rarely from these plants. The Bullfinch and Hawfinch obtain much of their food by crushing fruits, seed‐heads, etc. in their bills and peeling off the outer layer to get the seeds. The methods used by the crossbill species to open cones of varying degrees of hardness are described in detail. The Chaffinch and Brambling obtain almost all their food by rapid pecks; they show none of the behaviour patterns used by carduelines to open various types of seed‐heads.Species also differ in the proportion of food obtained from the ground, from vegetation, or on the wing. These differences are related to the various positions in which each species is able to feed. Those species (Goldfinch, Siskin, Redpoll and Crossbills) which are most adept at clinging and hanging feed mainly from trees and herbaceous plants, while those that are least adept at this (Chaffinch and Brambling) obtain almost all their food from the ground or from firm horizontal twigs. The remaining species are intermediate in the proportion of time spent feeding from the ground or from vegetation; and only the Chaffinch, Brambling and Bullfinch obtain an appreciable amount of food on the wing. Differences between species in the frequency with which various positions are adopted during feeding can be related to differences in their average body weights, and (to a lesser extent) in their leg‐structure; the most agile species are either light in weight or have relatively short strong legs. Body‐weight, leg‐proportions and bill‐size (and hence feeding habits) may vary considerably between different populations of the same species. In Appendix 2, the leg‐proportions of certain English finches are compared with those of their German and Russian counterparts.Some finch species use their feet in coordination with their bill to obtain food. The extent to which various species do this in the wild is discussed in relation to the ease with which they can be taught experimentally to pull up food suspended on the end of a long thread.The ecology, structure and behaviour of finches is discussed in relation to some current ideas on speciation and the ontogeny of feeding behaviour. The young of several species of finches respond initially to a similar range of potential food‐items (both in size and appearance) and all attempt to deal with them in similar ways. However, each individual soon learns to concentrate on those foods it can obtain most efficiently with its own particular structures and behaviour patterns. It is thus the structural and behavioural differences between closely‐related species which lead the individuals of each to prefer different foods. Further, some of the behaviour patterns themselves probably develop mainly asture, so that some of the behavioural differences between species that affect food‐choice are in turn dependent on structural differences. This implies that, from an evolutionary viewpoint, two forms need diverge only in structure (and not necessarily “psychologically”) for some ecological segregation to be achieved. There are, however, certain differences in feeding behaviour between the fringillines and carduelines that cannot be attributed merely to structural differences between the two groups, so presumably some “psychological factor” is also important in the development of these particular behaviour patterns.A close relationship between the structure, feeding behaviour and food of an animal is usually taken for granted, but it is often difficult to decide which of these came first in evolution. Among finches, however, there are sometimes indications that a structural change was necessary before a new behaviour pattern or feeding habit could evolve, though further modification of structure may then occur through adaptation to the new foods thereby made available.Some evolutionary trends among finches are described, and the role of competition in the evolution and maintenance of ecological differences between species is discussed.The effect of social experience on feeding behaviour is also discussed, and some examples are given of the spread of novel food‐habits among finches, and of presumed traditional differences in feeding behaviour between different populations of the same species. Finally, some recent changes in food, and habitat‐selection by finches are discussed in relation to problems of

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1967.tb00005.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

SummaryFurther experiments confirm our recently reported findings that Adelie PenguinsPygoscelis adeliae, transported from rookeries on the coasts of Antarctica to remote release points, consistently select a departure direction to the N.N.E. with respect to their home meridian. New releases were made at the South Pole where sun altitude is constant and in the offshore pack ice where the initial N.N.E. departure direction led the birds directly away from their home.Birds imported from the Mirnyy coast, 85° of longitude to the west of Cape Crozier selected a departure direction to the N.W. After being held in an open pen at the new position for three weeks, however, Mirnyy birds revised their orientation to match the N.N.E. departures of a comparably held group of Crozier birds.Juvenile penguins taken from creches and from the beach at Cape Crozier selected the same departure direction as adults.Several lines of evidence suggest that the mechanism used in initial direction selection may be different from that used in course maintenance.The consistent northward or outward departure orientation is discussed in terms of escape to offshore feeding grounds. The easterly component of this orientation is discussed in terms of compensation for a westward drift imposed on outward‐moving birds by coastal currents. A circadian rhythm in phase with conditions at the longitude of the home rookery is regarded as serving to guide a displaced bird back to its home coast. A circadian rhythm reset to the solar cycle of a new longitude is regarded as serving to guide a displaced bird to the nearest coast.The return of displaced birds to their home rookery, after initial orientation in other directions, emphasizes the fact that the departure response observed in these studies is only one part of a complex navigational mechanism, which guides the Adelie Penguin through its seasonal migratio

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1967.tb00006.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1967.tb00007.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1967.tb00008.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1967.tb00009.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1967.tb00010.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY