bluuebunny/crossref_metadata_2025_split huggingface dataset:
On the Position of the Genera Turdoides, Argya, Illadopsis, Neociehla, Ptyrticus, Maerosphenus and Pseudoaleippe in the Timaliidæ
Authors: Mackworth‐Praed C. W. , Grant C. H. B. 
Published: April 2008

Summary.Although in these five genera the long broad first primary and rounded wing agree with Timalia pileata, as does the profile of the bill of Argya fulvus and Argya rubiginosus, they do not do so in any other respect,. neither in their habits, nest and eggs, nor in the scutation of the tarsus. We therefore propose to remove them all from the Timaliidae and place them in two separate families, but leaving them in their present position in the classification as placed by Sclater in Syst. Av. Æthiop. ii. 1930.
Dimorphism in Stercorarius pomarinus (Temminck)
Authors: Southern H. N. 
Published: April 2008

SUMMARY.

Records from the literature are collected about the proportions of dark and pale forms of the Pomatorhine Skua.
The breeding range falls into two areas, one from Novaya Zemlya to north‐west Alaska, the other from the Mackenzie River to west Greenland. In both these areas dark birds are evenly distributed in the proportion of 1 in 5–20, though there is a slight suggestion that they. are less common in the second than in the first region.
This even, distribution contrasts with tile cline in dimorph‐ratio known to exist in the Arctic Skua.
Pomatorhine Skuas fluctuate in breeding strength from year to year. This is probably connected with the lemming cycle.
The Breeding Biology of Aquila verreauxi Lesson
Authors: Rowe E. G. 
Published: April 2008

Summary.The breeding behaviour of a family of Verreaux's Eagles at Mbulu, north‐central Tanganyika Territory, was watched, with the aid of African observers, for over 1000 hours during the later part of one breeding‐season and the whole of the next.These observations throw light on the extent of the hunting‐range, the breeding‐season, clutch‐size, incubation and fledging periods, the relative shares of the parents in incubation and in brooding and feeding the young, calls, enmity with a leopard, relations with other birds, the use of green twigs, maltreatment and death of the younger chick, the quantity and nature of prey and its preparation, the nestling's meals and fasts, the possible occurrence of the “starve‐out” process, the eaglet's preliminary efforts to leave the nest and maiden flight, and its early life on the wing until the disintegration of the family.
On the Systematic Position of the Starlings inhabiting Bulgaria and the Neighbouring Countries
Authors: Pateff Pavell , Stresemann. E. 
Published: April 2008

Summary.Ample material of breeding birds has shown that S. v. vulgaris and S. v. tauricus intergrade, through hybridization, over an area of considerable extent and that S. v. balcanicus is a hybrid between them.This result, combined with the conclusions reached by Stegmann (1935), considerably simplifies the problem of geographical variation in Sturnus vulgaris. Only six principal subdivisions can be maintained: (1) vulgaris (and its insular offshoots), (2) menzbieri, (3) caucanicus+nobilior, (4) taics+porphyronotus, (5) humii, (6) minor.Neighbouring races are connected by hybrid populations, some of which inhabit a large area. Among the names which have been bestowed on hybrids are S. vulgaris balcanicus = vulgaris×tauricus, S. vulgaris purpurascens=taricus×caucasicus, S. vulgaris poltaratzkyi = porphyronotus×menzbieri. S. vulgaris dresseri = porphyronotus×menzbieri, S. vulgaris dzungaricus=porphyronotus×menzbieri.Random combination of characteristics sometimes results in hybrids of different origin being almost indistinguishable (e. g.×dresseri and ×purpurascens, according to Sushkin, 1933).Within the area occupied by “pure” races there is rather slight individual variation in quality of iridescent colour. In S. v. vulgaris, for instance, two extremes of individual variation can be distinguished which are not evenly distributed over the whole range of the subspecies.
THE SIGNIFICANCE OF CLUTCH‐SIZE. Part III.—Some Interspecific Comparisons
Authors: Lack David 
Published: April 2008

Summary.

Average clutch‐size is characteristic for each genus and each family of birds in the same region.
In almost all families, clutch‐size is much smaller in equatorial Africa than in mid‐Europe.
In mid‐European small passerines, those with comparatively safe nesting‐sites tend to have larger average clutches and longer nestling periods than those building open nests.
Swifts and petrels have safe nesting‐sites and long nestling periods, but only small clutches, correlated with a scarce or uncertain food supply for the young.
In general, the length of the incubation period is correlated with the length of the nestling period in birds, probably because it is difficult to modify the rate of development except as a whole.
In nidifugous species, the specific differences in clutch‐size have not been accounted for, though food for the brood is thought to be the basic factor involved in most cases. The number of eggs that the hen Can cover is not a primary factor in most cases, but may sometimes provide a secondary limit.
NOTES ON THE ECOLOGY OF THE ROBIN
Authors: Lack David 
Published: April 2008

Summary.

In winter, in England, the Robin chiefly frequents cultivated land and the wood‐edge, but a few occur in the interior of woods. In summer, proportionately more frequent the interior of woods.
The Robin associates with man to a much greater extent in England than on the Continent of Europe. It seems first to have appeared round human habitations in winter, breeding being a later development.
The Robin suffers severely in hard winters, census figures being given in Table 2. During a cold spell, the woods may temporarily become empty of Robins, but it is not known whether most of these birds have died or moved out.
The Robin is “dimorphic”, some individuals migrating and others residing for the winter, the proportion in each class differing in different parts of Europe according to the severity of the winter. The activities of man have probably changed the proportion of residents to migrants in England.
Young Robins commonly disperse to breed between 1 and 4 miles from their place of birth, but only 5 per cent, have been found more than 8 miles from their birth‐place. Once a Robin has taken up a territory, it rarely moves more than a mile, only 3 per cent, being found 1–3 miles away and another 3 per cent, over 10 miles away.
The expectation of life for a Robin is about one year, and there is a suggestion that this figure is lower for north European migrants than for British birds.
The Robin eats a great variety of small invertebrates, which are chiefly detected from a perch as they move on the ground or litter below the bird. Seeds and fruits are also taken.
Particularly in hard weather, the Robin follows mammals or large birds which break up the ground, thereby rendering insects available to it.
In winter the Robin probably has no serious food competitors. In summer it takes many geometrid larvae, as do titmice and warblers, but this food is probably superabundant.
The Sparrowhawk is the only serious predator of the Robin.
The external parasites are listed.
More than 60 per cent, of adult Robins die each year. Winter food shortage is thought likely to be the chief mortality factor. Population control is briefly discussed.
There is no real evidence that territorial behaviour controls population density or that it is important in ensuring a food supply for the young.
SOME SUPPLEMENTARY NOTES ON THE BIRDS OF THE RHÔNE DELTA.
Authors: Yeates G. K. 
Published: April 2008

Summary.

The war has not affected the Camargue or its birds much.
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.
The early part of 1947 was unusually cold.
The following are the main changes since 1938:‐

Increases: Corvw monedula, Milvus migrans, Larus argentatus michahellis,
New breeding species: Merops apiaster.
Expansion: Coracias garrulus.
Decreases: Cettia cetti, Cisticola juncidis and Saxicola torquata (all three entirely gone); Remiz pendulimcs (slight); Gelochelidon nilotica (local); and, perhaps, Leucopolius alexandrinus.

Phmicopterus ruber bred in 1947. This species also nested successfully in 1942. Vanellus vanellus and, perhaps, Upupa epops and Athene noctua. 1500 pairs fledged about 2000 chicks.
THE FUNCTION OF THE HEAD‐COLORATION OF THE NESTLING COOT AND OTHER NESTLING RALLIDÆ.
Authors: Boyd H. J. , Alley Ronald 
Published: April 2008

Summary.Several hypotheses as to the function of the head‐coloration of nestling Coot are discussed with reference to the behaviour of the young. The evidence presented supports the view that the bright coloration serves to emphasize the signal‐movements employed by the young in obtaining food from adults.A review of the literature on the colouring of sixty other species and subspecies of the family Rallidæ reveals the prevalence of bright bill‐colours and the occurrence of bright head‐markings in several genera. It is suggested that bright bills represent the first stage in the development of emphatic coloration such as is highly developed in the Coot. Several intermediate stages have been described. Bright head‐markings are limited to those species in which the need for procryptic coloration is no longer paramount.
THE BLACK‐SHOULDERED KITE IN MASIRA (OMAN)
Authors: Green. Charles 
Published: April 2008

Summary.Some evidence is given to show that a small population of Elanus cæruleus has adapted itself to the desert environment of Masira Island by (a) substituting fish for rodents as staple diet, (b) nesting in caves in lava‐crags in default of suitable trees, and (c) having a much smaller brood.
BIRDS ON TENERIFE
Authors: Lack David , Southern H. N. 
Published: April 2008

Summary..1. A visit was paid to Tenerife in March 1948.2. Of 16 species common to Tenerife and Britain, all showed detectable differences in song or call‐notes. The differences were in some cases slight but in others very marked.3. Various species occupy broader habitats on Tenerife than in Western Europe, and this can in most cases be correlated with the absence of a related species which fills part of the habitat in Western Europe. For instance, on TenerifeParus cceruleusbreeds in conifers as well as broad‐leaved woods, andPhylloscopus collybitabreeds in low scrub as well as woods.4.Fringilla ccelebsis more restricted in habitat on Tenerife than in Western Europe. a fact which can be correlated with the presence of the relatedF. teydea.5. The bird fauna of the Canary Islands is recommended as a profitable field for ai detailed ecological study.
THE BREEDING SEASONS OF EUROPEAN BIRDS.
Authors: Lack David 
Published: April 2008

Summary.

In northern Europe, the northward movement of the sun in spring has so extensive an influence, that the food of all species of birds reaches its maximum at some time between late spring and early autumn. As a result, and in contrast to the tropics, nearly all species of birds lay their eggs in roughly the same period of the year.
A review of the breeding seasons of British birds reveals some interesting correlations between time of breeding and time of maximum food, and also many apparent puzzles, particularly as regards the marked differences in breeding season sometimes found between related species.
In Lapland, all species start breeding 1–2 months later than in Britain, and the breeding season is much less extended. As compared with Britain, the Corvidae and predatory birds of Lapland lay early relative to the small passerines, but among the small passerines, and also among the predators, the different species tend to breed in the same order relative to each other as they do in Britain.
Quantitative measurement of breeding seasons is much needed, and some examples showing the advantages of this method are given in Tables 1–3 and text‐Figs. 1–5.
It is considered that, through the action of natural selection, the breeding season of each species coincides with the time of year when offspring can be raised with greatest success. The major ultimate factor involved is, therefore, the food for the young birds (and hence the factors which determine the abundance and availability of this food). But there may be modifying ultimate factors concerned with the survival of the parents, of the nest and eggs, and of the juvenile birds in the period soon after they leave the nest.
Proximate factors provide a physiological timing mechanism whereby the gonads recrudesce, and eggs are laid, at such a time that, on the average, the young hatch at a season when there is sufficient food to raise them. In European birds, daylength seems the major proximate factor, but there are several modifying factors, perhaps including temperature.
NOTES ON THE LIFE HISTORY OF PICUMNUS MINUTISSIMUS IN SURINAM.
Authors: Haverschmidt By Fr. 
Published: April 2008

SUMMARY.A brood of Picumnus minutissimus was watched from October to March in Surinam.The circular nesting cavity in a dead branch of Erythrina glauca about 8 metres above the ground was carved by both birds. At first it was used as a sleeping place by two males and one female, but after incubation had been in progress for some time by only the female and one male.Incubation was shared by both sexes. They were very restless and peeped out of the hole at frequent intervals.There was only one youngster, to which both parents took food in the bill.The young bird left the hole when about 28 days old. Thereafter all three birds continued sleeping in it for at least 62 days.
DISCHARGE OF OILY FLUID BY YOUNG FULMARS.
Authors: Armstrong Edward 
Published: April 2008

SUMMARY.It is suggested that the squirting of oily fluid by the young Fulmar is a defence mechanism primarily against winged predators and that it has played an important part in enabling the species te extend its range from the Antarctic to the North Atlantic. The adaptation supports the view that the Fulmar is of Antarctic origin. The onslaught of air‐borne predators is so swift that any delay in squirting might involve disaster to the chick; consequently parents arriving within range are as liable as anything else to be received with a squirt. Apparently oil‐squirting evolved as a defence mechanism of the young bird and enabled the ancestral stock to abandon cavity‐nesting.
VARIATION IN THE SONG OF THE CHAFFINCH FRINGILLA COELEBS.
Authors: Marler. P. 
Published: April 2008

Summary.

A method is described for transcribing the song of the Chaffinch Fringilla coelebs, based on a division into two parts, the trill and the terminal flourish or phrase.
Songs from five separate localities—Pico in the Azores, the Seine Valley in N.W. France, the Thames Valley, N. Lancashire and the Scottish Highlands—are distinguished on the number and arrangement of note sequences, in the trill, and of notes, in the phrase.
Fourteen distinct types of trill were discovered and forty‐five types of phrase.
It is shown that both the trill and, more particularly, the phrase are highly variable even within one locality.
The numbers of possible phrase types which might be recorded by this method are calculated, and it is shown that most of these up to three notes have been discovered, that further investigation will quickly reveal more 4‐note and 5‐note types, but that the discovery of 6‐note and 7‐note types will be slow because of their comparative rarity.
It emerges that some song types are much more common than others. Trills of two or three sequences of descending pitch make up 83 per cent of the results and none of the other twelve types exceeds 3 per cent of the total.
In the phrase from 0 to 7 notes may be used, but those with 3–5 notes are most frequent. There is evidence for a preference for certain patterns within each number‐class.
It is shown statistically that geographical variation of song between the separate regions occurs and that the songs characteristic of any one area can only be described in statistical terms. The suggested existence of song types confined and exclusive to a particular region cannot be substantiated, although this condition is approached in one case.
From a comparison with data from Russia, it appears that the trills are similar to the Western European forms, but that the range of notes in the phrase is lower and that the mean number of notes per phrase is lower—1.99 as compared with 2.91.
The song variants are distributed as dialects, and it is shown that the formation of these can be understood in the light of work on song inheritance.
It is inferred from its phenotypic nature that the geographical variation of the Chaffinch song cannot still be regarded as an example of incipient speciation.
A CONTRIBUTION TO THE ORNITHOLOGY OF NORTH‐WEST AFRICA.
Authors: Snow. D. W. 
Published: April 2008

Summary.

Two expeditions were made to the forests of North‐West Africa in January‐February 1950 and April‐June 1951.
The mountains and forests are described. The discontinuity of the forests and the dry area of Western Algeria, where the forests are thin, are of particular importance in the distribution of the woodland birds.
It is shown that there is a close correlation between the rainfall of the different patches of forest and the number of species of resident woodland birds occurring in them.
An account is given of the bird populations of the different types of forest, as found by the writer in winter and spring.
The breeding seasons of the three Titmice in different habitats are summarized. There are differences of up to a month between the breeding seasons in different localities, but the order in which the three species breed is the same.
An annotated list is given of all the species obsened. R. regulus is added to the North African list.
THE BLACKBIRD IN SHETLAND.
Authors: Venables. L. S. V. and U. M. 
Published: April 2008

Summary.

The Blackbird Turdus merula has now bred on Shetland for about 70 years and colonized all but four of the inhabited islands. A few isolated territories occur in the hills.
Of 204 occupied nests 50% were inside buildings, 19% in stone walls and 18% in garden vegetation, all indicating man's importance as a precursor. Inside nests were used repeatedly; this may have survival value, enabling a third brood to be reared.
Breeding density, estimated over 9 square miles for three. seasons, was ca. 1 pair to 300 acres which would produce a total Shetland breeding population of roughly 1230 pairs. Territories were not usually contiguous and a breeding pair would often roam over ca. 40 acres.
The egg‐laying period (April‐July) is later than in England and breeding changes such as song and beak colour are correspondingly delayed. There is no autumn or winter song.
The average of 117 clutches was 4.32, which is significantly higher than the average (3.9) for 483 British nests. The origin of this difference is discussed. Average brood size, nesting success and breeding curves are given.
Of 403 nestlings ringed, 237 also carried colour rings. Returns and sight records over four years show that the young birds remain in or near the parent territory until 6–7 weeks old, then establish themselves in an area providing food and cover where they remain all winter. First‐winter returns are all within 5 miles of the nest. About March a further move is usually made to establish a breeding territory. Of eleven ringed birds located breeding, seven were within 1 mile of the parent nest, and in three cases the new breeding area was adjacent to the parent territory. Both sexes may winter in their breeding territory and isolated males often defend winter territory. As yet there have been no recoveries outside Shetland though birds over a year old have moved up to 31 miles to other islands in Shetland.
Dates and pattern of the spring and autumn passage are given, together with the ringing returns available. These show that Blackbirds from Norway and Denmark pass through to wintering grounds in Britain, while others from the same source remain in Shetland all winter.
Comparing the wintering population with that of summer we find a greater concentration round the crofting townships, total numbers are higher and the ratio is weighted in favour of males. Winter Blackbird figures from elsewhere in Britain suggest that this preponderance of males is more widespread.
THE WINTER WEIGHTS OF TITMICE.
Authors: Owen D. F. 
Published: April 2008

Summary

1500 weights of tits were obtained in the winter 1951–52 and in November and December 1952.
On average the birds weighed least in the early morning and most just before going to roost in the late afternoon. The increase in weight slackened off around mid‐day, corresponding with a decrease in feeding.
The average weights were inversely correlated with air temperature, owing to increased feeding on cold days.
Blue, Great and Coal Tits were on average heaviest in December (or possibly November) and weights then fell gradually.
It is suggested that the increase in weight by passerine birds in early winter is an adaptation for a potential shortage of food later.
COMMENTS ON ‘THE BIRD FANCYER'S DELIGHT’: TOGETHER WITH NOTES ON IMITATION IN THE SUB‐SONG OF THE CHAFFINCH.
Authors: Thorpe W. H. 
Published: April 2008

SummaryThe ‘Bird Fancyer's Delight’ (1717) is considered in the light of modern knowledge of the process of song‐learning in birds. Some conclusions (if Baron von Pernau (1716) as to song imitation are also discussed. A new example of the ability of the Chaffinch to incorporate song phrases from other species into its sub‐song is given. It is suggested that there is an important difference between its true song and its sub‐song in this respect and that this difference may throw light on the ability of some other finches to learn alien songs.
THE STRUCTURE OF THE FEATHERS IN CHLOROPHANES AND IRIDOPHANES (COEREBIDAE).
Authors: Aubek L. , Appleyard H. M. 
Published: April 2008

Summary.Structurally coloured feathers from the Coerebid Chlorophanes show atypical features. These may be connected with different conditions of compressibility during development, as compared with typical feathers and mammalian fibres; there, cortex is more compressible than medulla.The atypical cortex has a special function in connection with the structural shade. The conditions in Iridophanes are similar to those in Chlorophanes, but less marked. Close relationship between these two genera, as suggested by earlier authors, is therefore confirmed.
STRUCTURALLY COLOURED PATTERN MARKS ON THE INNER WEBS OF FLIGHT FEATHERS.
Authors: Auber L. , Mason Muriel V. 
Published: April 2008

Summary.Some Psittacidae and Coraciidae show the unusual feature of blue and green pattern marks restricted to reverse surfaces of flight feathers.The optical causes of the colours of these marks are identical with, and the morphological configurations similar to, those which typically cause these colours on obverse surfaces of feathers in the same families. The atypical marks may, however, have been evolved independently from the typically located colour.Colour patterns on flight feathers are discussed in relation to the mechanics of flight and to optical effect.