bluuebunny/crossref_metadata_2025 huggingface dataset:
FEEDING HABITS OF THE SOUTH POLAR SKUA CATHARACTA MACCORMICKI
Authors: Young E. C.
Published: April 2008

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

Ascension 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

Three 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

The 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

The 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.
RADAR AND VISIBLE MIGRATION IN NORFOLK, ENGLAND: A COMPARISON
Authors: Wilcock John
Published: April 2008

Comparison of radar and visible passage in Norfolk during autumn and spring is made. With following winds migrants fly high, well above visual range. With strong opposing winds migrants fly below the radar horizon. It is possible to detect high flying migrants by making observations lying supine, thereby adding useful data.
THE FAT RESERVES OF YELLOW WAGTAILS MOTACILLA FLAVA WINTERING IN SOUTHWEST NIGERIA
Authors: Ward P.
Published: April 2008

The 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

Minimal 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

Naive 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

The 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

The 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

Foot 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

The 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

Between 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

A 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‐granti

Columba arquatrix sjöstedti

Centropus monachus occidentalis

Apus affinis abessynicus

Motacilla clara chapini

Ixonotus g. guttatus

Andropadus I. latirostris

Alseonax adjustus obscurus

Erranornis longicauda teresita

Terpsiphone r. rufocinerea

Turdus libonyanus saturatus

Cossypha c. cyanocampter

Petrochelidon preussi

Cinnyricinclus l. leucogaster

Chalcomitra r. rubescens Cyanomitra oritis bansoensis Gymnoris d. dentata Quelea erythrops Spermestes bicolor poensis

The 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

Several 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.
TIMING AND SPACING OF BROODS IN THE BLACK‐HEADED GULL LARUS RIDIBUNDUS
Authors: Patterson I. J.
Published: April 2008

The nests of the Black‐headed Gull Larus ridibundus are closely aggregated into dense colonies and their use synchronized, these two phenomena together tending to produce a maximal clumping effect. Within such a colony however, nests were found to be spaced out to produce a non‐random uniform distribution. The commonest distance between neighbouring nests was found to be about one metre, in contrast to related species. This study was concerned with two aspects of this distribution pattern; its survival value and its behavioural causation.

It was found that pairs nesting just outside the colony had a much lower breeding success than those nesting in the colony and that nests on the colony fringe had a slightly lower success than those in the centre. Pairs laying during the peak laying period had a higher breeding success than pairs laying either earlier or later in the season. Since by far the most important mortality agent was predation, it seems likely that both clustering and synchronization of nesting function as antipredator systems and arguments in favour of this are discussed.

Variations in nest‐spacing within the colony were not correlated with variations in breeding success.

In the causation of the spacing between nests, territorial aggression was demonstrated to be an effective dispersion mechanism and the way in which this mechanism works was investigated in detail.

This spacing mechanism was not sufficient by itself to explain the observed densities, which were higher than one would expect from the aggression alone; there was also some tendency for birds establishing a new nest‐site to cluster close to others. The interaction between this, the territorial aggression of the residents and the subsequent avoidance responses of the settling birds, can explain the nest spacing pattern and probably also the observed densities.
ON THE BIRDS OF MOROCCO
Authors: Smith K. D.
Published: April 2008

Fifteen months were spent in Morocco. A few ecological aspects of the country are described, together with their influence on the dispersal of birds in winter. Some winter visitors are listed and discussed, several species were much commoner in the winter of 1962/63 than in 1963/64, in some cases presumably as a result of the cold weather in Europe, although in others not obviously so. Cold‐weather movements of gulls, Lapwings and Cranes were observed. Individuals of species that are normally trans‐Saharan migrants winter in Morocco in small numbers. Spring migration in southeast Morocco is excluded from discussion, but autumn migration in western Morocco is summarized and compared with existing data. The systematic list is devoted largely to winter visitors and passage migrants, but resident species are listed when new localities, breeding data or field notes warrant their inclusion. Six species not hitherto recorded in Morocco, were seen.
THE FOOD AND FEEDING HABITS OF SHELDUCK TADORNA TADORNA
Authors: Olney P. J. S.
Published: April 2008

The food and feeding habits of Shelduck Tadorna tadorna are described, based on the analyses of the viscera of 30 birds collected under special licence, and of 18 birds found dead or dying during the cold weather of 1963, on faecal material from eight incubating birds, on field observations and on the literature. The birds came from a number of different localities and from each month of the year, apart from July.

The mollusc Hydrobia ulvae (Pennant) was found in all 46 birds which contained food, and it is quite obvious, and this is confirmed by the literature and by faecal analyses, that this is the most important food item during much of the year and in many different localities. Other species eaten included the bivalve Macoma balthica, the amphipod Corophium volutator, the ragworm Nereis sp., the alga Enteromorpha, and occasionally the seeds of various plants.

The importance of H. ulvae is examined in the light of its distribution and numbers, which may be a strong controlling factor in concentrating Shelduck in certain areas at certain times of the year.

The feeding behaviour of Shelduck, and a number of other birds, is apparently closely related to the cyclic behaviour pattern of the main food species, H. ulvae.

It seems that Shelduck have a rather fixed type of feeding behaviour which exploits only one feeding niche and therein mainly one food item. Any event (prolonged gales or very cold weather) which prevents the bird from using that niche can be the cause of heavy mortality.
NOTES ON SOME RESIDENT BREEDING BIRDS OF SOUTHWEST KENYA
Authors: Betts F. N.
Published: April 2008

A description is given of the topography and climate of the Narok district of S.W. Kenya. The rainfall and its effect on the breeding of birds is discussed. A list is given of the avian biotopes of the district followed by a systematic list of breeding species with dates of breeding and altitudinal range of residence.
THE MOULT OF THE BULLFINCH PYRRHULA PYRRHULA
Authors: Newton I.
Published: April 2008

The distribution of feather tracts and their sequence of moult in the Bullfinch is described. The adult post‐nuptial moult, which is complete, lasted 10–12 weeks, and the post‐juvenile moult, which is partial, 7–9 weeks. Adult moult began with the shedding of the first (innermost) primary and ended with the replacement of the last. Variations in the rate of moult in the flight feathers were mainly achieved, not by changes in the growth rates of individual feathers, but in the number of feathers growing concurrently. The primaries were shed more slowly, and the onset of body moult delayed, in birds which were still feeding late young.

In 1962, the onset of moult in the adults was spread over 11 weeks from thc end of July to the beginning of October, and in the two following years over the six weeks, from the end of July to the beginning of September. The onset of moult was delayed by late breeding, which itself occurred in response to a comparative abundance of food in late summer, markedly in 1962. In all years, the first juveniles to moult started at the end of July, and the last, three weeks after the latest adults. Juveniles moulting late in the season retained more juvenile feathers than those moulting earlier.

During moult, adult and juvenile Bullfinches produce feathers equivalent to 40% and 33% respectively of their dry weights. In both, for much of the moult, an average of nearly 40 mgm. of feather material—some 0.6% of their dry‐weight–is laid down each day. The remiges of the adult comprise only a seventh of the weight of the entire plumage, and it is suggested that their protracted moult results not so much from their energy requirements, as from the need to maintain efficient flight. Variation in the rate of moult in the remiges was much less pronounced than in the body feathers. Bullfinches were less active during moult than at other times of the year. The weights of both adults and juveniles increased during moult.

The food during the moult period is described. In all years, most Bullfinches finished moulting just before food became scarce, even though this occurred at different times in different years. In one year, adults moulting latest in the season probably survived less well than those moulting earlier; the same was apparently true of the juveniles in all years. The timing of moult in the Bullfinch, and the factors initiating it, are discussed in relation to the breeding season and foodsupply near Oxford.
FURTHER EXPERIMENTS ON DISTANCE NAVIGATION IN THE ADELIE PENGUIN PYGOSCELZS ADELZAE
Authors: Penney R. L. , Emlen J. T.
Published: April 2008

Further experiments confirm our recently reported findings that Adelie Penguins Pygoscelis 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 migrations.
THE MIGRATION OF RAPTORS AND STORKS THROUGH THE NEAR EAST IN AUTUMN
Authors: Cameron R. A. D. , Cornwallis L. , Percival M. J. L. , Sinclair A. R. E.
Published: April 2008

Between 1963 and 1965 three expeditions have investigated the autumn migration of raptors and storks, on two occasions in southeast Turkey, and once in Lebanon.

Nearly all the soaring birds leaving Europe by the Bosphorus cross Asia Minor and turn south at the Gulf of Iskenderun. The commonest of these migrants are White Stork Ciconia ciconia, Honey Buzzard Pernis apivorus, and Eagles Aquila spp.

Other species such as Common Buzzard Buteo buteo are not usually seen crossing the Bosphorus, but occur in large numbers in the flocks seen south of the Gulf of Iskenderun. It is suggested that these are birds from Russia and north Turkey. Common Buzzards also occur on Cyprus in autumn, but their point of origin is not clear. Short‐toed Eagles Circuetus gullicus and vultures join the migration from their breeding grounds in Turkey and the Levant.

Different species tend to migrate at different times of year. White Storks, Egyptian Vultures Neophron percnopterus and Black Kites Milvus migruns move chiefly between late August and mid‐September, while eagles Aquilu spp. start in late September and continue until November. Other species are intermediate, or spread their migration out over a longer period.

The volume of migration at different times of day is discussed. No general conclusions are possible but in 1964 a correlation was obtained between cloud cover and the start of the migration.
BREEDING SUCCESS AND POPULATION GROWTH IN A COLONY OF HERRING AND LESSER BLACK‐BACKED GULLS LARUS ARGENTATUS AND L. FUSCUS
Authors: Brown R. G. B.
Published: April 2008

This paper describes the results of investigations into the factors affecting breeding success of the Herring and Lesser Black‐backed Gulls Larus argentatus and L. fuscus, in the large colony on Walney Island, northwest Lancashire, between 1962 and 1965. These investigations were concerned with the incubation period, and the first ten days after hatching.

The survival of chicks to ten days is 67% in Herring Gulls, and 56% in Lesser Black‐backs. Most of these losses occur in the period just after hatching and are due to “cannibalism” by other gulls. This form of predation does not appear to be masking any effects from starvation or disease.

The following factors contribute to egg or chick mortality:breeding too late (and, to a much smaller extent, too early); breeding in the open, as opposed to amongst cover; the facts that eggs in small clutches have a lower hatching success than those in large ones and that Herring Gull (but not Lesser Black‐back) chicks in small broods are less likely to survive to ten days than are those in large broods.

Chick mortality after the first ten days is not certainly known. About 30% of the eggs laid gave rise to fledged young— or about one fledged chick per pair.

In the Herring Gull, the average clutch size (2.56) is lower than that of the Lesser Black‐back (2.76). Both species show a seasonal decline in clutch size—this occurs earlier in the Herring Gulls than in the Lesser Black‐backs.

The Walney population, which stood at about 700 pairs in 1950, had reached 12,000 in 1957, and is at present about 18–19,000 pairs. It is suggested that this increase may be linked to the greater availability, or exploitation, of human garbage in the Morecambe Bay area. The population explosion between 1950 and 1957 must have been partly due to massive immigration and could not have come about through natural increase alone.

The possible influences of the gulls' behaviour on the population growth are discussed. There is no evidence of any “shock disease”, although the Walney colony is very crowded. “Cannibalism” is regarded, not as evidence of a failing food supply, but as an extension of the normal hunting behaviour of these omnivorous gulls; it will be an economical means of obtaining food only in a large, dense colony, such as Walney. It may be offset by increased breeding efficiency due to social factors.
INTERBREEDING OF LARUS NOVAEHOLLANDIAE SCOPULINUS AND LARUS BULLERI IN THE WILD IN NEW ZEALAND
Authors: Gurr L.
Published: April 2008

Five cases of interbreeding between the Red‐billed Gull Larus novaehollandiae scopulinus and the Black‐billed Gull L. bulleri in the wild in New Zealand are described. Captive hybrids from the wild population were shown to be fertile. Comparison between two years' observations in the same colony suggests that interbreeding occurs only when isolated individuals with a strong readiness to mate are prevented from mating with conspecifics. Other cases of interbreeding in Laws spp. support this conclusion.
FEEDING BEHAVIOUR AND DMNG RHYTHMS OF SOME NEW ZEALAND SHAGS, PHALACROCORACIDAE
Authors: Stonehouse Bernard
Published: April 2008

Records of the duration of the dives and resting periods of two species of Shags, which fish in the coastal waters of New Zealand's South Island, show the existence of an ecological segregation whereby each species is working within the limits of its greatest physiological efficiency. The smaller species hunts only in shallow water, the larger maintains efficient dive/rest ratios in deeper off‐shore water.
BIOLOGY OF THE IMMIGRANT CATTLE EGRET ARDEOLA IBIS IN GUYANA, SOUTH AMERICA
Authors: Lowe‐McConnell Rosemary H.
Published: April 2008

The success of the immigrant Cattle Egret Ardeola ibis in Guyana appears to be due mainly to its breeding biology, combined with man's activities in clearing and draining land for stock and by his selective shioting.

Long.‐established heronries are beine taken over bv the Cattle Egret. In Aurmst 1959 during the principal nesting season in the main rains 90% of the 1786 heron nests in the Botanic Gardens Georgetown, belonged to Cattle Egrets, the others to Little Blue Herons Hydranassa caerutea, Black‐crowned Night Herons Nycticorac nycticorux, Snowy Egrets Egretta thula, Tricolour Herons Hydranassu tricolor, and Streaked Herons Butorides striatus. In the December rains the same year another 1700 Cattle Egret nests were in use here, but no indigenous herons were nesting. These were, however, joined in January by Black‐crowned Night Herons, Snowy Egrets, Little Blue and Tricolour Herons.

In addition to having two peak nesting periods a year, instead of one as the indigenous herons generally have, the Cattle Egrets react faster to the onset of the rains and obtain the best nest‐sites, and they are helped by the tendency of the indigenous herons to display more aggressively against their own species than against the intruder; also now that Cattle Egret numbers are high they can find mates very rapidly. Both indigenous herons and Cattle Egrets have one to three young per brood in Guyana, and the nesting period lasts about two months.

The peak nesting time varies from year to year with the advent of the rains. Nesting appears to be stimulated by, and its success related to, rainfall. A cycle of wet years in Guyana preceded the arrival of the Cattle Egrets in North America in 1952. In Guyana their dispersal inland was restricted, probably by the forest, until 1961.
THE BIOLOGY OF OYSTERCATCHERS HAEMATOPUS OSTRALEGUS ON SKOKHOLM ISLAND, S. WALES
Authors: Harris M. P.
Published: April 2008

A population of about 50 pairs of Oystercatchers Haematopus ostralegus nesting on Skokholm Island, S. Wales, was studied between 1963 and 1965. Other information on Skokholm Oyster‐catchers over the last 25 years was also analysed.

The adults were trapped, colour‐banded and sexed by bill measurements. With few exceptions, birds kept the same mates and territories from one season to the next. Apparently the male is responsible for retaining the territory. Some Oystercatchers breed at three years but most do not do so until four or five. It seems that there is a high population pressure, preventing young birds from establishing themselves. The annual adult survival in the two years was 88% and 90% respectively.

The average clutch‐size on Skokholm is known for many years, and varied annually between 2.5 and 3.3. The number of c/4 varied greatly from year to year. There was a seasonal decline in mean clutch‐size and also in egg and nest success. Predation, especially by Lesser Black‐backed Gulls, was the main cause of egg loss.

In 1963, 36.7% of hatched chicks fledged and 59% in 1964. The larger clutches were more successful and produced more surviving young than did the more numerous smaller clutches. Early hatched young are more successful than later young.

The average yearly mortality of birds between fledging and breeding was 40%.
THE DELAY IN OVULATION PRODUCED BY pp'‐DDT AND ITS POSSIBLE SIGNIFICANCE IN THE FIELD
Authors: Jefferies D. J.
Published: April 2008

A significant correlation between pp'‐DDT intake by the female Bengalese Finch Lonchuro striata and delay in ovulation is reported. Linked with earlier work showing that pp'‐DDT can cause inhibition of the testicular growth and secondary sexual characters of cockerels, it is deduced that in this context the site of action of the pp'‐DDT is probably the pituitary or hypothalamus. Inhibition of the secretion of the pituitary hormones could explain the reported recent increase in egg breakages by predatory birds. It is also probable that organochlorine pesticides are responsible for the late breeding of several species of birds reported in the early nineteen‐sixties. This could affect a population in that large sublethal doses which double the time for egg laying could cause a double‐brooded bird to be out of phase with the food supply for the late broods.
PHOTORESPONSES OF THE WOODPIGEON COLUMBA PALUMBUS IN RELATION TO THE BREEDING SEASON
Authors: Lofts B. , Murton R. K. , Westwood N. J.
Published: April 2008

The gametogenetic response following photo‐stimulation was tested in Woodpigeons under controlled laboratory and aviary conditions. Subjects were wild‐caught adult or first‐winter birds or were hand‐reared from wild‐taken nestlings. The natural seasonal gonad cycle is described and experiments were related to this cycle.

Gonad recrudescence could be initiated in adults with regressed organs by exposure to summer photoperiods, while the normal vernal recrudescence could be prevented if birds were artificially kept on short (winter) daylengths. Thus Woodpigeons could be stimulated towards reproductive condition at seasons when the gonads of wild‐living birds remained inactive, viz. late September to mid‐February.

Juvenile males were unresponsive to extra photo‐stimulation until they were about six months old. This meant that some spermatogonial division could be procured in a few individuals in late February, but juveniles were not very noticeably affected by an extended photoperiod until mid‐late March. This is the time when juveniles first begin gametogenetic development in the wild, though spermatogenesis normally accelerates in April after which time the rate of gonad development is constant. First‐winter females were judged to resemble males in their photoperiodic responses but the sample examined was small.

The results confirm that the natural gonad cycle in the Woodpigeon is controlled (via gonadotrophic hormones) by seasonal changes in daylength. More important is the finding that the species appears to possess no post‐nuptial refractory period. Thus, at the end of the breeding season in September birds kept on summer daylengths were maintained in full reproductive condition until December. The testes of controls placed on winter daylengths regressed within one month, but they were immediately responsive to a summer daylength which stimulated spermatogenesis within a month.

The discussion argues that the avian refractory period is not a necessary period for gonad rehabihtation and reorganization and that it has not evolved as a fixed period serving to time the breeding season; views which until now have been current. Instead, it functions only as a safety mechanism, preventing unseasonal reproduction in those species for which natural selection favours seasonal breeding. In such species the evolution of sensitivity to a particular daylength could result in breeding taking place at the wrong time, for example spring responding species might also respond in the autumn. Because natural selection permits Woodpigeons to remain in breeding condition from March until September, without disadvantage, a direct response to natural daylength can regulate the cycle, and there is no need for a period of pituitary refractoriness. It is not known if some pigeons have lost the refractory period or whether they never possessed one.
SPRING MIGRATION AT THE BOSPHORUS
Authors: Collmait J. R. , Croxall J. P.
Published: April 2008

During observations made at the Bosphorus from 23 March to 6 April 1965, 3473 raptors were seen; the majority were Spotted/Lesser Spotted Eagles and Honey Buzzards. The migration of the main species is considered in some detail and attempts are made to correlate this with the prevailing weather. Comparisons are made with the records of observers both in spring and autumn at the Bosphorus and in spring at Gibraltar. Honey Buzzards pass in spring a month later at Gibraltar than at the Bosphorus. It is suggested that this is related to the timing of spring in the breeding areas to which these birds are returning. Notes on the observations of passerine movements and a night migration of Black Storks are also included.