bluuebunny/crossref_metadata_2025_split huggingface dataset:
FEEDING ECOLOGY OF TITS, WITH NOTES ON TREECREEPER AND GOLDCREST.
Authors: Gibb John 
Published: April 2008

SUMMARY

The feeding habits of the titmice, Treecreeper and Goldcrest were studied in a mixed broad‐leaved wood near Oxford, from April 1950 to August 1951, by means of repeated standard observations.
The proportion of time spent feeding varied inversely with the body‐weight of the species. A greater proportion of the time was spent feeding in mid‐winter, and in the breeding season when young were being fed, than in spring or autumn. Feeding intensity varied similarly.
Fighting for food was recorded most often in mid‐winter, and rarely in summer. Most attacks were intraspecific. Probably individuals gain or lose much food by fighting.
Although adult birds search for food most of the time when feeding young, they preen then as often as at other times.
The period and intensity of singing and calling was measured. This was often performed concurrently with other activities–mainly feeding–in the tits, least often by Great Tits, most often by Coal Tits.
Distant flight was more often recorded in winter than in summer.
The frequency with which the birds fed (a) in different species of trees and shrubs, and (6) at different feeding stations, varied significantly from month to month. The behaviour of the birds is described. The Parus species fed most diversely in autumn, and least diversely in early summer. Coal and Marsh Tits fed more diversely than Great and Blue Tits, which in turn fed more diversely than Longtailed Tits and Goldcrests.
The tit species were more distinctly segregated from each other by feeding habit in winter than in summer.
Food was especially short in mid‐winter and in the breeding season, and competition for food was most severe in mid‐winter. Hence mortality from food shortage is probably more density‐dependent in winter than in summer.
Although the several tit species have much in common, and often eat the same foods, each species has evolved characteristic methods of feeding, with corresponding structural adaptations; and each species occupies a more or less distinct feeding‐niche.
DURATION OF PARENTAL ATTENTIVENESS IN THE SOOTY SHEARWATER.
Authors: Richdale L. E. 
Published: April 2008

SUMMARYParental attentiveness in. the Sooty Shearwater Puffinus griseus was studied on Whero Island, near Stewart Island, New Zealand, in 1951‐52 and 1952‐53. In the first year 30 chicks were watched from 18 March until they left the burrow, and in the second year 57 chicks from 10 February (i.e. for practically the whole of the chick stage).The chief feature of the pre‐desertion period is the irregularity of parental attention (with wide individual variation). Inattentive periods range from 1 to 25 days (mean 4‐3), attentive from 1 to 11 days (mean 2–4).From 10 February to 31 March 1953, 13%‐65% (mean 37‐2%) of the chicks were visited nightly by parents; from 1 April to 18 April, 13%˜46% (mean 27'5%); and from 19 April to 4 May, 0 %–11 % (mean 3%). In the second period 43 chicks (76‐8%) were deserted by their parents, and in the third period all the remaining 13 chicks.Of 83 chicks which survived to leave the burrow in the 1951‐52 and 1952‐53 seasons, 58 (70%) left weighing more than 455 grams and 25 (30%) weighing less. Only the former group of chicks was believed to survive.Parents desert the breeding area in any given season apparently in answer to a migration urge, irrespective of the chick's age. Chicks hatched late therefore have little chance of survival.The length of time a chick remains in the burrow varies from 86 to 106 days (mean 97). The chicks leave the burrow apparently in answer to an internal urge, irrespective of the degree of parental attention.Before finally leaving the burrows, chicks may emerge at night and then return. Chicks more than 455 grams at departure emerged from 0 to 14 nights (mean 5–9 nights).The length of the desertion period is much shorter than we have been led to believe. For 58 normal chicks the period ranged from 0 to 27 days (mean 12 days). Chicks have been known to be fed just before departure and birds assumed to be parents have been known to enter the burrow after the chick has departed. If so, this means that these chicks departed in an inattentive period by the parent.The presence or otherwise of a desertion period in petrels depends on whether or not the species concerned is migratory. For example, as far as is known, migratory shearwaters have a short desertion period, but the non‐migratory Royal Albatross and other species have not.
DISPLAY OF THE HOUSE‐SPARROW PASSER DOMESTICUS.
Authors: Summers‐Smith D. 
Published: April 2008

Summary.Various forms of non‐communal display in the House‐sparrow are described. Pair formation is initiated by the male, which selects a nest‐site and displays beside it to attract a female. It is suggested that the display of a single male towards a female away from the nest is an intensive form of pair‐formation display and not, as has been suggested, an invitation to coition. The behaviour during coition, presentation and nest‐relief ceremonies, fledging behaviour, threat and aerial chasing are also discussed. The relationship between the displays and the posturings used in them is discussed.
THE BREEDING AND FEEDING OF JACKDAWS AND ROOKS WITH NOTES ON CARRION CROWS AND OTHER CORVIDAE.
Authors: Lockie J. D. 
Published: April 2008

Summary.

The nestling food and breeding of Jackdaws, Rooks, and to a lesser extent Carrion Crows were studied at Oxford from 1952 to 1954.
The average clutch‐size in the Jackdaw is 4–4 and in the Rook 4–3. Late clutches are significantly lower than early in the Rook but not in the Jackdaw. Annual variation in clutch‐size is small.
In both Rook and Jackdaw the survival of nestlings decreases as brood‐size increases. Predation, disease, and nest‐site are unimportant in producing this mortality; food‐shortage is very important.
In Jackdaws and Rooks the eggs hatch asynchronously and this is an adaptation to a variable food‐supply; by the speedy elimination of the small young in a brood when food is short, the brood is brought into closer correspondence with the food‐supply.
In the Jackdaw and Rook the brood‐size which effectively produces most young lies between four and five. This corresponds to the average clutch.
Rooks typically probe in grassland where they obtain earthworms which form the bulk of the food brought to nestlings. April is on average the best month for obtaining earthworms on grassland (or suitable alternative food) and this is the month when most young Rooks are in the nest. Jackdaws feed on the surface of open grassy places and have their young in the nest when many of the varied invertebrates in this habitat are most abundantly available. Carrion Crows feed partly in woods and partly on grassland. The nestlings are fed mainly on earthworms, nestling birds and small mammals.
The breeding season of the Jackdaw and Rook varies little from year to year. The food‐supply is unlikely to be a major factor in initiating ovulation since its season of abundance is variable.
TERRITORY IN THE THICK‐BILLED NUTCRACKER NUCIFRAGA CARYOCATACTES.
Authors: Swanberg P. O. 
Published: April 2008

Summary.

The main features of the territory in the Thick‐billed Nutcracker are:‐ (a) the territory is kept for life and inhabited throughout the year; (b) the special food, nuts, is stored in the territory; (c) song, copulation, nest‐site selection and nest‐building take place only in the territory; (d) territories examined were 11.2–14.9 hectares, averaging 32.7 acres, believed to be the normal size in Sweden.
There is no clear evidence that the territory has the function of securing more than a certain amount of food other than stored.
The territory is respected by other Nutcrackers as to its main functions, while simple visits by other Nutcrackers and ceremonial gatherings in the territory are tolerated.
Both territory‐holders attack intruders that try to take nuts but as they do not chase them out the behaviour is not regarded as truly territorial behaviour.
The territory is proclaimed by the calls, the song being exclusively sexual.
Unmated birds have not been recorded with territorial behaviour.
When the special food is limited and the nesting habitat ample, the population is limited by the amount of the special food; but when the special food is abundant and the nesting habitat limited, over‐crowding seems to be prevented by territorial behaviour.
It is suggested that the function of territory in the Nutcracker is to give the holders a well‐known refuge from predators, to serve as a food storing place, and by spacing out to prevent these positive qualities from reduction by overcrowding.
TERRITORIAL ACTIVITIES OF THE AMERICAN ROBIN TURDUS MIGRATORIUS.
Authors: Young Howard 
Published: April 2008

Summary.American Robins show territorial behaviour in the springtime by partially isolating themselves on areas and displaying intolerance of varying degrees towards intruders. Territories are established by the males; the females later help in maintaining the boundaries. These boundaries are not precisely defined, and claimed areas often overlap. Excessive trespass and frequent fights are characteristic in this species. Inter‐sexual combat occurs, and the males are dominant to the females. Possible functions of territory in this species include:helping to ensure a food supply, enhancing the opportunities for mating by dispersal of the males, and maintenance of the pair bond.
RECENT FIELD OBSERVATIONS FROM IRAQ.
Authors: Chapman E. A. , McGeoch J. A. 
Published: April 2008

SummaryThe paper includes an introduction to, and a systematic list of observations made in Iraq from August 1952 to August 1954. At least six species appear to have been added to the Iraq list, and at least six breeding species to the list of breeding birds in Iraq. The extension of breeding range, winter range, summer range and breeding seasons of several species is discussed. The migratory seasons of many species are noted and the westerly passage of Hirundinidae and Motacilla sp. in late summer is recorded.
A SPECIFIC CHECK LIST OF THE BIRDS OF GREECE.
Authors: Lambert Anthony 
Published: April 2008

Summary.This paper consists of a catalogue of all species known to occur in Greece. Indications are given of the status, distribution and relative abundance of all these (except rare vagrants and accidentals), in the north, centre and south of the country, and of the habitat or habitats in which they are generally found. The notes on each species are based on the studies mentioned in the list of references and on personal knowledge of the country gained during three years' residence from 1952–1955.
EXPERIMENTS ON BIRD ORIENTATION AND THEIR INTERPRETATION.
Authors: Kramer Gustav 
Published: April 2008

Summary.Among birds, the ability of sun‐azimuth orientation has been demonstrated experimentally in Starlings Sturnus vulgaris, Meadow Larks Sturnella magna, Barred Warblers Sylvia nisoria, Red‐backed Shrikes Lanius collurio and homing pigeons. Sun‐azimuth orientation consists in determining compass directions by the sun position regardless of time of day, hence mainly in the ability of correcting for the sun's daily azimuth displacementEvidence indicating the innateness of the underlying mechanism is not complete, but suggestiveThe estimation of the sun's speed must be considerably independent of personal experience. Individual Starlings differ in appraising the hourly angle of displacement in spite of their being constantly exposed to the natural sunThe internal clock which is normally in phase with the astronomical day‐night cycle can be controlled and shifted by an artificial light‐dark cycle. The bird shows the deviation of its personal clock by producing determinate direction choices. The direction choices are equal to those produced by birds kept in outdoor conditions if the artificial light‐dark change is synchronized with the astronomical day‐night cycle. They deviate in a predictable manner if the artificial cycle is shifted. A shift by six hours results in a final directional deviation of roughly 90°. An exposure of 4–12 days to the phase‐shifted light‐dark cycle is sufficient to attain the full shift of the internal clock, which demonstrates that its “rigidity” is limitedRecent advances in the problem of night orientation are reviewed. There is strong evidence of orientation by stars. The most convincing fact is oriented migratory activity under an artificial sky (planetarium)Recent facts are submitted supporting the ability of directed homing independent of familiar landmarks. At least in some areas the homing success depends upon the direction of displacementIn the winter months a marked weakening of the homing ability of homing pigeons is observed in Northern Germany, at distances of 14–50 milesOvercast skies handicap both homing success and initial orientation at distances down to 7‐5 milesDay‐to‐day variations in homing success are observed which cannot be explained in terms of traditional meteorologyNo direct evidence for bi‐coordinate sun‐navigation is available. The hypothesis of sun‐arc navigation, based upon the observation of very short sections of the sun's path, is criticized theoretically. The main supporting experiments are re‐analyzed; one of them has been repeated and could hot be confirmed. On the whole the evidence in favour of this hypothesis is considered insufficientThe explanation of homing orientation is still lacking. Prospects for a future experimental approach are discussed.
THE BREEDING OF THE BLACKBIRD TURDUS MERULA AT OXFORD
Authors: Snow D. W. 
Published: April 2008

Summary1. Breeding statistics are given for a garden population of Blackbirds, and less complete data for a woodland population. Comparison is also made with data provided by the British Trust for Ornithology nest‐record cards.2. The breeding season lasts from March to June. Temperature influences the timing of the start of breeding, and rainfall probably influences the ending of breeding. Yearling females tend to begin to breed later than old females and to stop a little earlier. Old females averaged 3·1 broods per year, yearling females 2·3. Breeding begins later in woodland than in gardens.3. Yearling females lay smaller clutches than old females. Clutches are on average smaller in gardens than in woodland. Smaller clutches are laid when the weather is cold and perhaps also when it is very dry.4. Incubation starts gradually while the clutch is being laid. Consequently hatching is usually spread over a period of a day or two. Hatching success was about 90% in gardens, old parents being more successful than yearlings. Hatching success in woodland was 92 to 95%.5. In gardens, nestlings are fed mainly on earthworms in the early part of the breeding season, later on a greater variety of food, especially insects. In droughts food is hard to find and many nestlings die. In woodland, nestlings are fed especially on green caterpillars and a variety of other invertebrates taken from the woodland floor, and few were found to die in the nest.6. The young grow from about 6 gm. to 70 gm. The last‐hatched are often much lighter than the first‐hatched. If food is short, the lightest young usually die one by one. The weight of eight‐day‐old nestlings is highest in the middle of the breeding season. Young from large broods are on average heavier than young from small broods. The flight feathers emerge at the age of seven or eight days, but may be delayed for up to two days by food shortage.7. Brood‐size at eight days has been higher in woodland than in gardens, partly because clutches are larger in woodland and partly because many nestlings die in the garden nests. Proportionately more young die in the nest from large than from small broods.8. After leaving the nest, the young are fed by the parents for about 20 days. Parents very rarely feed strange young, and do not always feed all their own. Especially the last brood of the season may be strictly divided between the two parents.9. The garden population has produced an average of 4·1 young per pair per year, and 66% of them have survived to independence. Post‐fledging survival seems to have no relation to weight at the age of eight days. It is probable that at least 62% of young that reach independence survive to the next breeding season. The woodland population has been much less successful on account of heavy predation.10. The adaptive nature of the breeding season and clutch‐size is discussed.
A CONTRIBUTION TO THE BIOLOGY OF THE CAPE PROVINCE WHITE‐EYES (ZOSTEROPS)
Authors: Skead C. J. , Ranger G. A. 
Published: April 2008

SummaryEvidence of the inter‐breeding of grey‐bellied Zosterops (atmorii) and green‐bellied (virens) at King William's Town, C.P. is presented.In habitat, behaviour, voice, and breeding biology no differences can be found between them.The roosting and flocking habits are discussed.Whereas both lay blue eggs, only the green‐belly (virens) has so far been found to lay white eggs.Incubation periods, ascertained to within a few hours, are mostly between 10 and 11 days.Details are given of the nestling and post‐nestling periods.Both insects and fruit are taken and fed to young. Z. pallida on the Orange River is very similar in habits. There is a noticeable difference in tonal quality of voice but the general patterns of the calls are the same.
THE BIRDS OF THE SANTA ELENA PENINSULA, S.W. ECUADOR
Authors: Marchant S. 
Published: April 2008

SummaryA systematic account is given of the birds of the Santa Elena peninsula in S.W. Ecuador, based on three years observations (1954‐7) and a collection of 425 skins. The status of individual species is decribed and the different elements of the avifauna discussed, viz. the Equatorial arid fauna, Nearctic migrants, sea‐birds, and other wide‐ranging forms and waterfowl. Seasonal movements of species of the Equatorial arid fauna are indicated in greater detail than has been previously known. The effect of a recently constructed reservoir on the bird life is mentioned. More detailed knowledge of the occurrence of species from the cold Humboldt current is provided. Several additions to the Ecuadorian list are given, and some birds recorded which were hitherto unknown or very rarely recorded from the west coast of S. America. Various matters of taxonomy affecting races of birds along the whole west coast of S. America are discussed.
THE RETURN AND DEPARTURE OF SWIFTS APUS APUS AT OXFORD
Authors: Lack David 
Published: April 2008

SUMMARY1. The return in spring and departure in autumn of resident Swifts was studied in six years, primarily by means of a nightly check of roosting birds.2. The mean date of return in spring has varied by nine days in different years. The return was delayed with a cold northerly airstream, but not otherwise.3. Soon after its return in spring, a bird sometimes spent a night or two away from the tower.4. Sometimes in spring, but hardly ever in autumn, a transient Swift spent one night in the tower; occasionally, three adults then roosted together.5. The number of residents in the tower at the end of May was about 90% of that in the preceding late summer.6. Members of the same pair usually returned and departed on different days.7. The mean date at which the adults departed in autumn depends primarily on the date when breeding started, and hence on the weather in May.8. The parents usually stayed for a few days after their young had left, presumably to put on fat. This interval was longer in those years in which the weather in July had been bad, and in one year it was longer for parents of larger than smaller broods, while it was shorter, irrespective of other conditions, late in the season. Occasionally one, but never both, parents departed before the last of their nestlings, chiefly in fine summers.9. Adults which laid eggs which failed to hatch tended to leave before the parents of young, but non‐breeding pairs (mainly yearlings) tended to leave later than parent birds that raised young.10. Autumn departures were held up by depressions, and occasionally by mist.11. After their mates had departed in autumn, a few individuals “kept company” with other residents, courting and roosting with them.12. In autumn the birds usually departed from the tower inconspicuously, but twice Oxford residents probably joined a large flock of passing migrants.
THE BREEDING SEASON AND CLUTCH‐SIZE OF THE ROOK CORVUS FRUGILEGUS
Authors: Owen D. F. 
Published: April 2008

Summary.

Annual variations in the breeding season of the Rook near Oxford could be correlated with mean air temperatures in the period prior to egg‐laying.
The most frequent clutch‐size was four to five, and in five out of six years, broods starting as five raised on the average more young than broods starting as four, even though not one brood of five was completely successful. In the other year, broods starting as four and five raised on the average the same number of young per brood.
THE COMPOSITION OF GOOSE POPULATIONS
Authors: Boyd Hugh 
Published: April 2008

Summary.Detailed knowledge of changes in the size and composition of goose populations is of importance in conservation. Long‐term inventories of goose numbers have so far been made only in the United States of America. American and European studies of movement, and of survival, have chiefly depended on the recovery of ringed geese. It has slowly been realised that direct observations of goose flocks can provide much of the information needed to determine the age‐structure of flocks, annual breeding success and mortality. Studies of goose populations employing all the available techniques are now being actively pursued in Britain as well as North America. Some examples are briefly discussed.
BIRD NOTES FROM ADEN AND OMAN
Authors: PAIGE J. P. 
Published: April 2008

SUMMARY1. Extensions are given of the recorded range (Meinertzhagen 1954) or periods of occurrence of certain species.2. Spring passage of waders at Aden was light except for Grey Plover Charadrius squatarola. There was a very noticeable passage of shrikes there 30 April‐12 May.3. Individuals of many species of northern‐breeding waders were recorded in summer.4. A light but steady S.W. movement of birds was noticeable at Aden from the beginning of July onwards. Waders began to increase in numbers by the middle of the month, and by the first week in August quite large flocks were present.