摘要:

Summary.1 Qualitative knowledge of the food of many birds is fairly complete, but on the quantitative aspects of the problem there is little exact information.2 The materials available for the study of bird foods include not only stomach contents and pellets, but also dung, the rejectamenta of meals, accumulated stores, the field notes of observers and photographs.3 The sampling in many studies has been irregular or inadequate. In a number of species the collection of statistically satisfactory samples of stomach contents from any one locality or habitat may be impossible.4 Foods may be assessed by frequency of occurrence, by enumeration, by weight or by volume. The weights or volumes may be measured “as found” or by approximations to the weight or volume of the food at the time of ingestion. There is no one ideal method, and the food of each species or group of species should be investigated and assessed by the methods which seem to be most appropriate.5 Published records and summaries should be in such form that they can readily be combined with the results of other investigations.6 The lack of fundamental ecological knowledge makes it impossible to pronounce upon the “economic status” of any species, save in a few

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1948.tb01700.x

出版商:Blackwell Publishing Ltd    

年代:1948

数据来源: WILEY

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1948.tb01701.x

出版商:Blackwell Publishing Ltd    

年代:1948

数据来源: WILEY

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1948.tb01702.x

出版商:Blackwell Publishing Ltd    

年代:1948

数据来源: WILEY

摘要:

Summary.Bird‐plant communities are described. Moorland: effect of incomplete forest barrier in extending population as compared with Kilimanjaro. Upland grasslands: four subdivisions with distinctive avifauna tabularly compared. Upland bushland: two subdivisions. Evergreen forest. Upland waters. Intermediate scattered‐tree grasslands: lodgment of distinctive populations. Ground‐water forest. Lake and swamp: comparison between populations of Lakes Natron, Manyara and Embagai; analysis of migrant movements and biotic preferences among waterfowl.Breeding seasons: contrast between upper and lower zones, in some cases implying biological races of common species.Evolutionary significance of population; probable recent development of the four or five endemics; very mixed affinities of the remainder, which include forms associated with Kilimanjaro, Chyulu, Kenya Highlands, Lake Victoria basin, Uganda and S.W. Tanganyika, considered to indicate rather recent colonization, but in some instances survival from an earlier epoch.Systematic notes on 23 species of special interest, including a review of the East African races ofColius striatus, field‐notes on newly described races ofPinarochroa sordidaandCisticola hunteri, and a first account of the nesting ofNectarinia jo

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1948.tb01703.x

出版商:Blackwell Publishing Ltd    

年代:1948

数据来源: WILEY

摘要:

Summary.1 The war has not affected the Camargue or its birds much.2 The dry period 1938 to 1946 caused great drops in water levels, and has adversely affected such species as Cisticola juncidis, while others have been restive and capricious, notably Egretta gazetta, Nycficorax nycticorax and Ardea purpurea. The wet winter of 1946/47 greatly improved water levels. The chief victims have been Cettia cetti and Saxicola torquata.3 The early part of 1947 was unusually cold.4 The following are the main changes since 1938:‐(a) Increases: Corvw monedula, Milvus migrans, Larus argentatus michahellis,(b) New breeding species: Merops apiaster.(c) Expansion: Coracias garrulus.(d) Decreases: Cettia cetti, Cisticola juncidis and Saxicola torquata (all three entirely gone); Remiz pendulimcs (slight); Gelochelidon nilotica (local); and, perhaps, Leucopolius alexandrinus.5 Phmicopterus ruber bred in 1947. This species also nested successfully in 1942. Vanellus vanellus and, perhaps, Upupa epops and Athene noctua. 1500 pairs fledge

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1948.tb01704.x

出版商:Blackwell Publishing Ltd    

年代:1948

数据来源: WILEY

摘要:

Summary.1 The Olivaceous PiculetPicumnus olivaceuswas studied in the basin of E1 General in southern Pacific Costa Rica. It inhabits shady pastures and plantations, second‐growth vegetation and the forest edges from sea‐level to at least 3000 feet. It feeds chiefly in very slender dead branches and twigs, to which it clings without using its rounded tail for support. Ants and their immature stages form an important part of its diet, which includes also other insects and larvae.2 The neatly rounded cavities, used both for nesting and for sleeping at all seasons, are carved in dead trunks of very soft wood (Heliocarpusa favourite) or in decaying fence‐posts, at 3 to 12 feet above the ground. Male and female share the task, each working in the absence of the other. One hole was completed in four or five working days.3 The piculet nests chiefly during the dry season, January to March inclusive, but laying continues until at least May. Three, or less often two, pure white eggs are laid on consecutive days.4 During the whole period of laying, incubation and rearing the nestlings, male and female sleep together in the breeding nest, and also sometimes for two weeks or more, before the eggs are laid. By day they sit alternately for from a half to nearly two hours at a stretch. One often enters the hole before the other comes out (a difference from most woodpeckers); and they may then remain inside together for a few minutes. A pair watched for an entire day kept their nest constantly occupied. The eggs tend to hatch on successive days after about fourteen days.5 The nestlings at birth are naked (pink) and blind. At eight days the pin‐feathers are becoming prominent and the eyes partly open. The feathers begin to unsheath at about 16 days, and two days later the nestlings are fairly well clad. They begin when three weeks old to look through the doorway, and they emerge at 24 or 25 days.6 The nestlings are fed and brooded by both parents. Food is brought in the bill and mouth rather than regurgitated. Immature stages of ants appear to form the bulk of the nestlings' diet, especially when they are younger. Later, mature ants and larvæ of other kinds are added. The parents keep the nest scrupulously clean.7 The nestlings take food with a forward thrust of the head and grasping movement of the bill. This is continued after they have received all that the parents have for them, and greatly annoys the latter.8 After their first flight the fledglings are led back to sleep in the nest‐cavity with their parents, and may continue to do so for at least three or four months. The family retires early, especially on rainy evenings, and emerges late in the morning, after most birds of other kinds.9 During the second half of the year piculets are most often found sleeping in pairs, occasionally in threes, rarely one.10 A nest of Lafresnaye's PiculetPicumnus lafresnayeiin the eastern foothills of the Andes of Ecuador contained two eggs. A male and two birds in female plumage slept in the hole with the eggs. By day the male, and at least one female, took turns at incubation. They spent much time

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1948.tb01705.x

出版商:Blackwell Publishing Ltd    

年代:1948

数据来源: WILEY

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1948.tb01706.x

出版商:Blackwell Publishing Ltd    

年代:1948

数据来源: WILEY

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1948.tb01707.x

出版商:Blackwell Publishing Ltd    

年代:1948

数据来源: WILEY

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1948.tb01708.x

出版商:Blackwell Publishing Ltd    

年代:1948

数据来源: WILEY

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1948.tb01709.x

出版商:Blackwell Publishing Ltd    

年代:1948

数据来源: WILEY