bluuebunny/crossref_metadata_2025_split huggingface dataset:
FEEDING HABITS OF THE SOUTH POLAR SKUA CATHARACTA MACCORMICKI
Authors: Young E. C. 
Published: April 2008

Summary.This paper compares the feeding habits of two groups of skuas breeding at Cape Royds. Six of the many skua pairs nesting in the area were able to obtain food at the penguin rookery while all others fed at sea. Observations are recorded establishing the reality of this division and how little most skuas were attracted to the rookery. Neither the order of settling of the skua colonies nor the flight paths used by the breeding birds to the feeding grounds were influenced by the location of the rookery. Non‐breeding birds settled in one rookery territory in late summer but obtained little food there.Courtship feeding was commonly observed and the food often identified. The male usually fed the female immediately on return to the territory after foraging flights and less commonly at other times after being begged for food. The female was fed in this way until the chicks hatched and again if the eggs or chicks were lost. Both birds foraged while the chicks were being reared. The female of rookery pairs was less often fed by the male as food could be taken on the territory.The most common fish taken by the skuas was Pleurogramma antarcticum. Large fish were swallowed head first.The feeding habits of the two groups of birds were only partly different. Birds feeding at sea flew to the feeding areas, mainly to the north of Cape Royds, at least twice daily throughout summer. Rookery pairs gained food from the penguins, but except for a short period when penguin chicks could most easily be taken they also fed at sea. There was little food at the rookery before mid‐November, in early December and after late January. From late January all skuas fed at sea. Even 400 nesting pairs of penguins did not provide sufficient food for a skua pair.It was concluded that the two species were not closely associated in breeding, the timing of which is related to the short span of suitable conditions rather than to the requirements of feeding at the rookery. The maximum amount of available penguin food does not coincide with the time of maximum requirements of young skuas; in fact, at that time it is almost exhausted. Moreover, skuas are little adapted for preying on penguins.
THE FRIGATE BIRD FREGATA AQUILA OF ASCENSION ISLAND
Authors: Bernard  , Stonehouse Sally 
Published: April 2008

SUMMARYAscension Island Frigate Birds (present population 8,000–10,000 breeding adults) were studied on Boatswain Bird Island between November 1957 and April 1959. Eggs were laid throughout the year, but a breeding season of eight to nine months (April to November or December) was apparent in 1958 and there was evidence of a similar season in the previous year. The birds tended to nest in groups, at densities varying from one or two to over 60 per area of 50 square metres; some nested at densities of two or three per square metre. Nesting success was highest among early breeders, out‐of‐season breeders and those breeding in low‐density groups, and was very much lower in the areas of dense nesting; greatest losses were among eggs and young chicks, and a nesting success of 15°‐20° is indicated for the population as a whole. Courtship, nesting and growth of the chicks are described.
NOTES ON THE BIOLOGY OF THE BROWN NODDY ANOUS STOLIDUS ON ASCENSION ISLAND
Authors: Dorward D. F. , Ashmole N. P. 
Published: April 2008

SUMMARYThree colonies of Brown Noddies on stacks north of Georgetown, Ascension Island, were visited 24 times between November 1957 and April 1959. During this period there were two main breeding seasons, about a year apart, but in each season there was both an early and a late peak of laying: rollers washing over the stacks may have been partly responsible for this. The moult cycle of the Brown Noddies was probably an annual one, but on Ascension there appeared to be no tendency for moult to stop during breeding: this situation contrasts with that found in other populations of the species. A small number of food samples were obtained, which showed that the diet of the noddies included a variety of fish and some squid. Young Brown Noddies in many parts of the world show a polymorphism in down colour which is still very poorly known; on Ascension most chicks are almost white, about a sixth more or less dark. Diagrams showing the growth of young noddies are given. The age and state of development at which young Brown and Black Noddies and Fairy Terns first fly are considered, and the reasons for the differences between different species and populations are briefly discussed.
FACTORS INFLUENCING CLUTCH‐SIZE AND CHICK GROWTH IN THE NORTH ATLANTIC GANNET SULA BASSANA
Authors: Nelson J. B. 
Published: April 2008

SummaryThe Gannet lays only one egg, and replacements are common. In 1962 in Scotland the Gannet was shown to be capable of hatching two eggs and rearing two young of the same age. If one of the brood of two was younger it did not survive. In striking contrast, S. leucogaster and S. dactylatra hardly ever manage to rear two young even though they normally lay two eggs.The results of artificial “twinning” showed that hatching success was as high for two eggs as for one, though the incubation period was two days longer, and that fledging success was 83% against 94% (of eggs hatched). This gave the parents of twins a 76% greater output than singles. The twins grew almost as well as singles, though weighing slightly less than a single of the same age, and taking on average four days longer to fledge. These figures refer only to twins of approximately the same age.The twin growth curves are compared in detail with normal single‐chick curves and with twin‐Shag growth curves, The results are discussed in terms of a possible causal mechanism related to feeding behaviour, since, though twin Gannets grow equally as well as each other, and, in the later stages, as well as singles, they are always slightly behind due to a lag which occurred early in growth when the actual amount of food consumed was extremely small.The results are thus apparently at striking variance with the theory that the Gannet rears the maximum number of young that it can feed; but it is still necessary to know how well the twinned Gannet young survive to breeding, and whether the rearing of an extra chick imposes a real strain on the adults (signs of which were beginning to show by the time the young fledged) which in long‐lived birds might offset the reproductive advantage of producing twins. It is suggested that, particularly in sea‐birds, this problem is worth exploring more systematically than has yet been done. Catastrophic years are thought unlikely to weed out twins, since to offset the 76% reproductive advantage would require such years to occur improbably often.Finally, the results are discussed in terms of the Gannet's social behaviour, in particular its well‐developed aggression, which is concerned with site‐defence, and affects the Gannet's food gathering power by requiring constant site attendance by one or other parent throughout the nestling period. In this sense, aggression may partially act as a population control mechanism. The relevance of these results to Wynne‐Edward's theory of animal population control mechanisms is briefly considered.
THE GOLDEN EAGLE IN RELATION TO ITS FOOD SUPPLY
Authors: Brown Leslie H. , Watson Adam 
Published: April 2008

SummaryThe population of Golden Eagles was assessed in four different areas of the Scottish Highlands. The average area per pair varied from 11,400 to 17,884 acres, excluding country that was not used by the eagles.Eagle food in these areas consists largely of Red Grouse, Ptarmigan, Mountain Hares and Rabbits, and also dead Red Deer and dead sheep.The numbers and biomass of the four main species of living prey were assessed by representative counts in three main types of habitat; and of dead deer and sheep partly from counts but mainly from published data on stocking densities, mortality and weights.The annual food requirement from a home range was estimated at 249 kg. of meat, calculated from data on the food consumption of eagles, allowing for known breeding success and for the presence of some immature eagles and unmated adults; and this was compared with the total food potential in the four Study Areas, allowance being made for the inedible portions of carcases.The average food potential in all areas is greatly in excess of the requirements. In the three western areas living prey is very scarce, but amounts of carrion are large and the eagles in these areas depend mainly on carrion. Large differences in food potential between areas do not correspond with differences in eagle density. Two examples are cited where a drastic reduction in food supply had no effect on eagle density, which remains remarkably constant in spite of seasonal and annual fluctuations in food supply.Golden Eagle nest‐sites are used over many years, and the home ranges are big enough to supply a more than adequate food supply at all times of year. Evidence is provided of territorial or home‐range defence, which generally takes the form of display flights but occasionally involves more overt aggression. The home‐range size is fixed so high that a critical food level is probably very rarely reached.
THE FAT RESERVES OF YELLOW WAGTAILS MOTACILLA FLAVA WINTERING IN SOUTHWEST NIGERIA
Authors: Ward P. 
Published: April 2008

SummaryThe fat contents of 85 Yellow Wagtails wintering at Ibadan, southwest Nigeria, have been determined. The mean fat value remained fairly constant at around 5% of their body‐weight from October till March, with a rapid increase in April to 20–30%, and a maximum recorded value of 30·6%. These fat deposits are of similar proportion to those found elsewhere in long‐distance migrants about to make a sea or desert crossing, though the initial 800 km. of the northward journey made by Ibadan birds is over country where food and water is plentiful.The pattern of fat acquisition, plumage characters, and other considerations suggest that the population sampled must breed in the belt where the ranges of Motacilla f. flava and M. f. thunbergi overlap, probably in Scandinavia.
ASPECTS OF THE BREEDING BIOLOGY OF THE GULLS
Authors: Harris M. P. 
Published: April 2008

SummaryMinimal weights of testes in Larus argentatus, L. fuscus and L. marinus were found to occur during November and December, and minimal ovary weights between August and January. Details are given of the changes in gonad size in relation to the breeding cycle.L. argentatus on Skomer Island (Wales) nests in colonies mainly on the cliffs, fuscus has colonies on flat vegetated areas, whilst marinus is normally a solitary nester.In all three species the third egg of a clutch is usually much smaller than the other two.Weights of embryos of known age were collected and growth curves are given. The overall increase in weight from laying to hatching is 2·6 gm. per day for embryos of marinus and 2·0 gm. per day for those of argentatus. The rate of growth is not uniform, however, being greatest up to the 15th day. From 8 to 15 days the rate of growth for embryos is approximately 25% per day.Series of growth curves for young of each of the species were obtained. It appears that the number of chicks in a brood does not effect the rate of growth but rather the fledging weights, b/1 young weighing more than chicks from b/2 or b/3.Details are given of a pair of argentatus successfully fostering a strange chick, about 21 days old, when they had lost one of their brood of two.It was shown by experiments in gulls fostering young of other species that there is more than enough food available for maximum growth.In 220 argentatus nests followed from the laying of the first egg to hatching or failure, the average clutch size was 2·8 and average brood size 1·8. It is suggested that argentatus nearly always lays a c/3. c/2 is less successful than c/3 in hatching.The young of about 360 pairs of argentatus were followed as far as possible during development. About 30% fledged successfully giving 0·6 chicks per pair.79 pairs of fuscus in an experimental area laid an average of 2·7 eggs per pair and hatched 1·8 young per pair. It was not possible to follow the fate of the chicks after hatching but the success rate seemed to be at least 50% of the chicks hatched.The causes of death in young gulls are listed and discussed. Predation and cannibalism are the main reasons for the loss of chicks of argentatus and fuscus on Skomer. Parasites, lack of food and disease are unimportant.
THE SWALLOWING OF FISH BY YOUNG HERRING GULLS
Authors: Hunt G. L. , Smith W. J. 
Published: April 2008

SummaryNaive Herring Gull chicks seize and swallow fish by the head end. In experiments with 16 hand‐raised chicks it was determined that the choice is made simply by recognition of the wider or thicker end of the fish. The position of the eyes, fins, gill opercula, etc., appeared to be ignored. Speculations are advanced about the possible adaptive significance of swallowing fish head first.
THE TAXONOMIC STATUS OF THE AFRICAN SILVERBILL
Authors: Harrison C. J. O. 
Published: April 2008

SummaryThe taxonomic status of the African and Indian Silverbills, cantans and malabarica, was examined. The characters used to isolate these birds in a separate genus, Euodice, are not generically valid, and the birds agree in morphology and behaviour with species of the genus Lonchura. The two silverbills show a general similarity in appearance and behaviour but differ in plumage pattern and colour. The call notes are similar but the songs are distinctly different in form, although they appear to share a common basic pattern. In captivity the two forms show evidence of preferential mating and lack of recognition which suggests that they would maintain their identity if sympatric. On this basis they are regarded as two species, Lonchura cantans and L. malabarica.
THE FLEDGING OF THE GUILLEMOT URIA AALGE WITH NOTES ON THE RAZORBILL ALCA TORDA
Authors: Greenwood Jeremy 
Published: April 2008

SummaryThe chicks of the cliff nesting auks go to sea when only one‐third the weight of the adults and before the flight‐feathers are fully grown. Sea‐going occurs in the evening (except in the high Arctic) and the advantages and disadvantages of this timing are discussed.In the Guillemot, the behaviour which occurs on the ledges before the first‐flight consists of ritualized intention movements, serving to synchronize the behaviour of parent and chick so that when the latter jumps from the ledge the parent follows it.The “water‐call” is made by all chicks when they arrive on the water (many of them make it on the ledges just before flighting). It serves to direct the adult to the chick.A parent and chick swimming out to sea may receive mock attacks from adults unaccompanied by chicks on the water below the cliffs. These birds direct their activities mainly to chicks whose parents have not joined them on the water, but do not adopt them and they ultimately perish.High winds and rough seas depress fledging activity. Low temperatures and rain seem to have no comparable effect. The number of chicks whose parents do not join them on the water is proportionately higher on rough, windy evenings.The fledging of the Razorbill follows a very similar course to that of the Guillemot.Predation, mainly by gulls, of auk chicks at the time of fledging may be high, though fewer chicks perish as a result of predation alone than as a result of desertion by their parents.
USE OF THE FEET IN FEEDING BY THE GREAT TIT PARUS MAJOR
Authors: Yince M. A. 
Published: April 2008

SummaryFoot preferences in the Great Tit were investigated (1) in holding small food terns and (2) in the more complex “string‐pulling” situation. Consistent preferences were found, which were more obvious in the simpler situation. These preferences were then used to supplement scoring methods in investigating the development of the use of the foot in feeding in hand‐reared Great Tits from the time of fledging to about three months of age. Two feeding patterns were distinguished: a one‐footed pattern when insect food was held, and a two‐footed pattern for holding seeds. The results show that (a) attempts to hold food with the feet are discernible almost immediately after fledging; (b) during the first few days after fledging the two‐footed pattern for holding seeds becomes distinguishable from the one‐footed pattern for holding mealworms; (c) considering means only, changes indicating the development of greater stereotypy with age are evident for about six weeks when seeds are held, and for about seven or eight weeks when mealworms are held and eaten, although a more detailed investigation into “skill” in the holding of mealworms shows development possibly beyond three months after fledging.A problem also considered was whether the skilled use of the feet in feeding depends on the maturation of a species specific pattern of behaviour alone, or on learning. Four experiments were carried out. The results indicate (1) that all the hand‐reared birds, whether reared with or without access to objects which could be held by the feet, manifested some approximation to the customary one‐ or two‐footed feeding patterns as soon as they were given the opportunity to do so; (2) that birds reared with a minimum of access to small portable food (or other objects which could be held by the feet) for 12, 22 and 35 weeks responded to seeds with an abnormally high intensity as soon as these were provided: (3) that birds restricted as in (2), but tested on rare occasions during the 35 weeks of restriction, showed a process of development in the use of their feet similar to that of birds reared under unrestricted conditions, but much less rapid; and (4) that birds reared under normal caged conditions but deprived of mealworms until two months after fledging then dealt with mealworms less skillfully than a control group given a few mealworms daily from the time of fledging. It is concluded that the use of the feet in feeding by the Great Tit is an example of species‐specific behaviour which depends on learning for its detailed normal development in the individual.
BREEDING AND FEEDING HABITS OF THE BLACK WHEATEAROENANTHE LEUCURAIN SOUTHERN SPAIN
Authors: Richardson Frank 
Published: April 2008

SUMMARYThe breeding and feeding habits of the Black WheatearO. leucurawere studied in an arid, rocky canyon region near Almería in southeastern Spain from October 1961 to May 1962. Strict territoriality appears to be absent in the species except around nesting sites and birds foraged in extensive and overlapping areas without intraspecific reactions. The rock‐carrying habit of the species is its most unusual characteristic. Great numbers of rocks, each one often weighing over half the weight of the bird (the largest rocks found weighed 28 gm.; a male wheatear weighs about 38 gm.). are used in building a foundation for the nest usually placed in holes or cracks in caves or on cliffs. This habit has probably taken on the function of an advertising display and may be continued even at inappropriate nest‐sites as a compulsive pattern of behaviour. Even thousands of rocks accumulate over the years under some nest‐sites. Incubation was approximately 16–17 days, and only the female incubated. Attentive and inattentive periods of incubation were recorded. Fledging took 14–15 days.Most feeding by Black Wheatears was on the ground, but fairly frequent flights, sometimes rather long, were taken to catch insects in the air. Some feeding was done on bushes and in caves or dark rocky recesses. Sardinian and Dartford Warblers and Chiffchaffs were seen a number of times to follow and feed near wheatears for no apparent reason. Large body‐size, relatively long beak, and bristly modifications of feathers in the beak region aid the Black Wheatear in successfully and safely handling large or poisonous insects and lizards and obtaining food in thorny bushes.Analyses of droppings and pellets showed that the most important food was beetles, of which eight families were identified, especially Chrysomelidae (Chrysomela affinis, the most common species), Scarabeidae, and Tenebrionidae. Ants of several species were also a frequent food in all months. Honeybees were an important item. Millepedes were occasionally taken, andAsparagus acutifoliusfruits. Masses of insect exoskeletal parts are disgorged as well‐formed pellets, presumably formed in the strong muscular gizzard. Such pellets are not strictly comparable to raptor pellets containing large indigestible parts.
THE SEA‐BIRDS OF GOUGH ISLAND
Authors: Swales M. K. 
Published: April 2008

SUMMARYBetween November 1955 and May 1956 continuous observations were made on the sea‐birds of Gough Island. These have been augmented by further occasional observations during seven subsequent years, and are compared with all previous published records for the island.A check‐list of 30 species of sea‐birds has been compiled and substantiated, as far as possible, by a series of skins of 20 species.Nearly 900 sea‐birds cf 20 species were caught and measured, considerably more than at any previous time there; in the case of eight species, these are analysed in detail and some are compared with those from other populations.The relative status of each species was estimated, together with total breeding populations where possible. In same cases the distribution of nests was mapped.A detailed sound and photographic record, of 14 and 16 species respectively, was made.Numbers of Wandering Albatrosses Diomedea exulans dabbenena and skuas Catharacta skua hamiltoni were ringed and colour‐marked respectively to enable a more detailed study to be made of them.General observations were made on the nesting seasons, breeding behaviour and moult of various species which are treated systematically.
A THIRD CONTRIBUTION TO THE ORNITHOLOGY OF THE BRITISH CAMEROONS
Authors: Serle William 
Published: April 2008

SUMMARYA collection of over 1, 900 skins made in Southern British Cameroons 1955–1957 is described. The range of many forms is extended.The field habits of many forms are described and there are observations on the nidification of the following:Francolinus bicalcaratus ogilvie‐grantiColumba arquatrix sjöstedtiCentropus monachus occidentalisApus affinis abessynicusMotacilla clara chapiniIxonotus g. guttatusAndropadus I. latirostrisAlseonax adjustus obscurusErranornis longicauda teresitaTerpsiphone r. rufocinereaTurdus libonyanus saturatusCossypha c. cyanocampterPetrochelidon preussiCinnyricinclus l. leucogasterChalcomitra r. rubescens Cyanomitra oritis bansoensis Gymnoris d. dentata Quelea erythrops Spermestes bicolor poensisThe stomach contents of several hundred specimens are noted and recorded in such general terms as fruit, seeds, or insects. Taxonomy. The following races are regarded as invalid: Streptopelia vinacea savannae, Gymnobucco calvus major, Bradypterus barratti youngi, Anthreptes fraseri cameroonensis.The following controversial races are upheld: Tympanistria tympanistria fraseri, Pedilorhynchus comitatus camerunensis. Megabyas flammulatus is regarded as a species without races.
THE FAT CONDITION OF SOME ISLAND BIRDS
Authors: Grant P. R. 
Published: April 2008

SUMMARYSeveral resident passerine species of birds on the Tres Marias islands, Mexico, are in a fatter condition than their mainland counterparts just prior to, and at the beginning of, the breeding season. At least two non‐passerine species on the islands are also fat at this time of the year. The significance of the fat reserves of the island birds is discussed, and it is concluded that the fat may serve the functions of energy‐storage and possibly water‐storage, to be used later at the climatically most unfavourable time of the year.