bluuebunny/crossref_metadata_2025 huggingface dataset:
BIRD MIGRATION AT ELAT, ISRAEL
Authors: Safriel U.
Published: April 2008

Several years' observations at the head of the Gulf of Aqaba are summarized. Migrants occur the whole year round, but most numerously in March‐April and September. Only a few of the 185 species recorded pass the winter at Elat. About 25 species are recorded more in autumn, whereas about 50 species are commoner in spring. The causes of these disparities are discussed. Thousands of soaring raptors pass through, mainly in spring. In spring only, thousands of Lesser Black‐backed Gulls stream through Elat, and many rest there for a short period. Mass migration of storks occurs too, more conspicuously in spring than autumn. An attempt is made to construct the routes of these birds between Eurasia and Africa, by analysing published sight records of raptors and storks and ringing recoveries of gulls. It is suggested that many of these birds move in autumn on a wide front, which may include Arabia, but that the core of the spring passage is shifted westward and part of it is channelled through the Rift Valley north of the northern end of the Red Sea and in the areas between the rift and the Mediterranean (Fig. 4). Supporting evidence is still needed from Arabia and the coasts of the Red Sea, especially from its southern end, where birds may be concentrated at the straits of Bab‐el‐Mandeb, as they are over the Bosphorus. Pelicans and a few other species perform very late southerly movements. These movements involve small numbers of birds, which may belong to late‐breeding populations.

About 45 other species of water and shore birds have been recorded, many of which occur in winter. With the expansion of areas of artificial water, some of them have become very common.

About 75 passerines, near‐passerines and other migrants pass through. The numbers involved suggest that the movement is on a broad front. Out of about 50 species whose passage is adequately recorded for seasonal comparison, 30 are more common in spring. Most of these are also commoner in other eastern Mediterranean countries and in Iraq in spring, md are presumed to perform a continuous overhead flight in autumn. Cases of “loop‐migration” among these species are rare.
PATTERNS OF GROWTH IN BIRDS
Authors: Ricklefs Robert E.
Published: April 2008

Parameters used to characterize the course of growth are described, and calculated growth parameters are presented for 105 species of birds of many taxonomic groups from a wide range of geographical localities.

Growth parameters are found to exhibit as much as 20% variation within a species with respect to geographic locality and time of the nesting season. There is also considerable local variation, irrespective of season and locality, which is related to nutrition and perhaps to an inherited variability. The application of curve‐fitting as a method of analysing intraspecific variation is discussed briefly, and the importance of comparative growth studies is emphasized.

Growth patterns are correlated with other parameters of the life‐history to evaluate the extent of diversity in the course of growth. Low rates of growth and prolonged growth periods occur primarily in species large for their families and in oceanic species. In most others, high rates of growth are maintained for longer periods of time. The shape of the growth curve is not related to the mode of development (i.e. whether precocial or altricial).

Overall relative, or weight‐specific growth rates, as measured by the constants of fitted growth equations, are most highly correlated with the adult body size of the species, changing as the ‐0–278 power of adult body weight. Smaller variations in the rate of growth appear to be correlated with differences in nesting success; open‐nesting passerines grow faster than hole‐nesting species of a similar size. Growth rate is further correlated with brood size. Oceanic species with single egg clutches and tropical land‐birds with small clutches have low growth rates.

The asymptote of the growth curve of the young (in relation to the adult weight) is related to the foraging behaviour of the adults. Aerial feeders generally have high asymptotes while those of ground feeding species are usually below adult weight. These differences are related to the need in the former for well‐developed flight at the time of fledging.

The diversity of growth patterns is related to evolutionary trends which are the result of (1) selective forces acting at stages of the life‐history cycle other than development, (2) factors which affect the survival of offspring during the growth period, and (3) adjustments made to balance the energy budget of the family group. The last trend is discussed in detail in relation to the correlations found in the analysis. Two hypotheses are presented. Firstly, in species which cannot gather enough food to support even one young at a normal growth rate, the pace of development is reduced to decrease the energetic requirements of the young. Secondly, in species with small clutches, where adjustments to feeding capacities are not readily made by changing brood size, growth rate may be adjusted to accomplish this. The lack of critical energetic data to test these hypotheses is emphasized as a major deficiency in our understanding of the breeding biology of birds.
THE AUTUMN MIGRATION OF SOARING BIRDS AT THE BOSPHORUS
Authors: Porter Richard , Willis Ian
Published: April 2008

The migration of soaring birds was observed at Küçük Çamlica at the southern end of the Bosphorus between 14 July and 8 November 1966. Simultaneous watches were also carried out at other points on the Bosphorus on a number of dates. The largest movements of birds of prey occurred on days of light northeasterly winds, the largest movements of storks on days of light winds with a southerly component. On most days the stream of migrants appeared to be concentrated over the southern end of the Bosphorus. Migration frequently occurred right throughout the day, though the peak period was usually not spread over more than three hours. Figures are given for the daily times of migration of the commonest soaring birds. Daily counts of soaring birds (storks, raptors and Cranes) migrating over the Bosphorus at Küçük Çamlica are given. The main species found migrating were (with total number recorded in brackets) White Stork Ciconia ciconia (207,145), Black Stork C. nigra (6,194), Honey Buzzard Pernis upivorus (8,997), Buzzard Buteo buteo (12,949), “Spotted” Eagle Aquila clanga/pomarina (4,309) and sparrowhawk Accipiter nisus/brevipes (5,224). The autumn migration of 1966 is discussed in detail in a systematic list. Buzzards B. buteo were recorded in large numbers for the first time at the Bosphorus, and were the commonest bird of prey. Cranes Grus grus were also recorded for the first time. Comparison is made between our results and those of previous workers, though differences of coverage rule out any firm conclusions.
BEHAVIOUR OF THE BLUE‐CROWNED HANGING PARROT LORICULUS GALGULUS WITH COMPARATIVE NOTES ON THE VERNAL HANGING PARROT L. VERNALIS
Authors: Buckley Francine G.
Published: April 2008

The maintenance activities of Loriculus galgulus and L. vernalis are described and discussed, and compared with the behaviour of the parrots of the genus Agapornis. Maintenance activities reveal some adaptations to the genus‐typical habit of resting and sleeping upside‐down. A peculiar defaecation posture ensures that the plumage of hanging birds is not soiled.

L. galgulus holds food either in the foot or in the bill, but L. vernalis seems not to use the foot in feeding:there is much regurgitation and remastication of food.

Scratching is indirect, as in the Agapornis species, though the foot is brought directly to the bill to be preened. Loriculus is more ready to bathe in standing water than is Agapornis, actually entering the water, and not merely splashing from the edge. There is some evidence that L. galgulus rain‐bathes hanging upside down, as does A. cana.

Agonistic behaviour is highly ritualized in Loriculus:some actions are identical with those of the more primitive species of Agapornis. Threat displays are described: the so‐called Super Threat Display combines all agonistic actions in one. There are three appeasement displays.

Group upside‐down pseudo‐sleeping as a response to the appearance of potential predators is frequent in both species: it is not certain if this is a displacement reaction or a normal escape reaction to the safety of an inaccessible refuge.

Little is known about reproductive behaviour in captivity and even less about behaviour in the wild. Pair formation appears to occur late in the period of attaining maturity, and to be initiated and maintained by courtship feeding: homosexual pairing is not unusual n flocks of captive birds. Of the courtship displays, one‐Strutting‐seems to be common to several Loriculus species.

Cutting of nest material is an activity of both male and female Loriculus. A maturing or learning process is seen in the cutting of little “bits” by inexperienced and immature birds, and by the cutting of straight or arcuate strips by those more experienced. In Loriculus galgulus, females were seen to tuck strips of nesting material in the throat and breast feathers, though they have been reported to tuck material into the rump feathers also: L. oernalis females tucked arcuate strips among the rump feathers only. Both male and female L. galgulus and L. vernalis investi‐ gated nest boxes, but none actually nested.

This study in general reinforces the ideas about the relationship of the genera Loriculus and Agapornis but more data on other Loriculus species are needed. At this stage of investigation it appears that both L. galgulus and L. oernalis are behaviourally closest to the more primitive species of Agapornis, namely, cana, tarantu and pullaria.
ORNITHOLOGICAL TRANSECTS IN THE NORTH ATLANTIC
Authors: Sage Bryan L.
Published: April 2008

An analysis is presented of observations made in the North Atlantic from 14 August to 10 September 1966, and comparisons are made with previously published data relating to this area. The majority of the records were obtained during transects along latitudes 55° N. and 58° N., but other data were collected in Labrador and Newfoundland coastal waters. During the period spent at sea 30 species were recorded, including five passerine species that came aboard ship. Manx Shearwaters were seen in Newfoundland waters where there have been few previous records. The record of a Balearic Shearwater appears to be the most northerly to date. Some evidence of correlation was found between the numbers of Great Shearwaters seen and the surface water temperature, but there was little evidence of correlation in the case of the Fulmar. Other points of interest are the records of moult in the Great Shearwater, and the records of Grey Phalaropes and Sabine's Gulls. An analysis of the skua movements suggests that the Arctic Skuas seen originated from Scandinavia, the Great Skuas from Iceland and the Pomarine and Long‐tailed Skuas from the Canadian arctic.
THE INFLUENCE OF BROOD SIZE ON THE ENERGY METABOLISM AND WATER LOSS OF NESTLING GREAT TITS PARUS MAJOR MAJOR
Authors: Mertens J. A. L.
Published: April 2008

At normal outdoor temperatures there is a distinct influence of brood size on the heat production of ten‐day‐old Great Tits. One ten‐day‐old nestling proved unable to maintain its body temperature at 12°C. Two ten‐day‐old tits together in one nestbox at 12Á°C were able to elevate the air temperature sufficiently to maintain homoiothermia. The same of course holds for tits in larger broods.

At an air temperature of 18°C, six or seven ten‐day‐old tits placed in a nestbox elevated the air temperature to a level at which they almost reached a state of hyperthermia: their metabolism was at the basal level. The basal metabolism of a ten‐day‐old tit was found to be slightly more than 0–1800 kcal/h. The metabolism intensity of 12 tits in a nestbox at 12°C was of the same order of magnitude.

Tits in broods comprising more than 12 or 13 nestlings at normal outdoor temperatures probably develop hyperthermia, which is unfavourable both for their energy and for their water balance.
THE MIGRATION OF PASSERINE NIGHT MIGRANTS ACROSS THE ENGLISH CHANNEL STUDIED BY RADAR
Authors: Parslow J. L. F.
Published: April 2008

An account is given of the migration of British summer resident small passerine night migrants across the English Channel in spring and autumn, as detected by radar.

The main times of passage of each species have been determined from the trapping records of Dungeness Bird Observatory.

The tracks of the migrants are consistent with the view that they always head about NNW in spring and SSE in autumn but may be drifted by a cross‐wind.

The wind‐direction and speed had a paramount influence on the volume of migration in both spring and autumn. Temperature had no effect in autumn, and though there was more migration with warmer than cold weather in spring, this need not have been due to the influence of temperature as such.

Small reversed movements occurred, with southerly winds in autumn or, more doubtfully, with northerly winds in spring.
A COMPARATIVE STUDY OF THE EGG WHITE PROTEINS OF SOME SPECIES OF THE AVIAN ORDER GRUIFORMES
Authors: Hendrickson H. T.
Published: April 2008

No agreement has been reached on the classification of the avian order Gruiformes as defined by Peters (1934) and Wetmore (1960). Starch gel electrophoresis of egg white proteins was therefore carried out in an attempt to obtain additional taxonomic data. Individual and intrafamilial variability was observed to be small, and the protein patterns thus seem to provide a basis for classification above the familial level.

These protein patterns, together with the historically conventional characters, suggest that a relationship exists between the Rallidae, Heliornithidae, Eurypygidae, Turnicidae, and Psophiidae; and that the Gruidae and Aramidae are not far removed from this assemblage. The Aramidae are thought to occupy a separate but intermediate position between the Gruidae and the rail‐like assemblage. The Otididae have a very different pattern which, together with the unusual combination of classical characters, suggests that the bustards should be removed from the order. The insufficient sampling from the Cariamidae and Rhynochetidae does little to clarify their systematic positions.
THE ENDEMIC BIRDS OF SEYCHELLES
Authors: Gaymer R. , Blackman R. A. A. , Dawson P. G. , Penny Malcolm , Penny C. Mary
Published: April 2008

A brief description of the islands is followed by an account of the 13 surviving endemic land‐birds, based largely on the results of the Bristol Seychelles Expedition 1964–65.

The whole of the Seychelles avifauna could possibly be derived from Madagascar, but anomalous distributions suggest that some species colonized the Seychelles from the northeast, either en route for Madagascar, or independently of the Madagascan colonists.

The Seychelles birds show insular evolutionary characteristics in colour and size, and some are extremes of their taxa.

Endemic and introduced birds are listed in the appendix, with a Summary of their present and former distributions. A list of vagrant land‐birds is included.
THE EVOLUTION AND SYSTEMATICS OF BEE‐EATERS (MEROPIDAE)
Authors: Fry C. H.
Published: April 2008

Behavioural and ecological characters are used in addition to structural ones in considering the systematics of the Meropidae. The two species of Nyctyornis are the most primitive extant forms. Meropogon is retained as a monotypic genus for forsteni, and all other bee‐eaters are placed in the single genus Merops, being ecologically and morphologically rather uniform except in details of wing and tail structure, which should be considered only of specific importance. M. breweri and M. oreobates are thought to be secondarily rather than primarily forest species.

With the submergence of Aerops and Melittophagus, and the monotypic genera Bombylonax and Dicrocercus, which are considered to be closely related to the pusillus species‐group, Merops is enlarged to 21 species which are uniform except in tail‐shape, wing formula and throat feather structure. These characters are of specific importance only, and have a mosaic distribution within the genus. Their use in the definition of the formerly recognized genera results in an artificial classification. The proposed delimitation of species‐groups within Merops differs somewhat from previous arrangements, and affinities argued in the text are summarized in Fig. 15, which shows superspecies and species‐groups. The species recognized are formally tabulated below.

The Meropidae probably originated in southeast Asian forest and spread through former forest to Africa. Only in Africa was the open‐country environment invaded, and speciation in the savanna was in two main directions, producing small sedentary and large migratory species. Representatives of both types returned to Asia in open country. From the present distribution of species it is inferred that speciation has proceeded under the main influences of (1) isolation of a population and its habitat in Pleistocene Africa and (2) isolation of migrants away from their breeding range. The distributions of species with wide or rather limited ranges are discussed in terms of physiological adaptation and ecological competition.

Opinion has not been expressed on the validity of subspecies, which have been discussed only in delimiting controversial species. In the following summary, the only subspecies named are those affected by changes from Peters' scheme (cf. Table 1). Superspecies are bracketed.

Nyctyornis amicta

N. athertoni

Meropogon forsteni

Merops guloris

M. mülleri

M. bulocki

M. bullockoides

M. pusillus

M. variegatus (?loringi, oariegatus, lafresnayii, bangweoloensis)

M. oreobates

M. hirundineus

M. breweri

M. revoilii

M. albicollis

M. orientalis

M. boehmi

M. viridis

M. superciliosus (persicus, chrysocercus, superciliosus)

M. philippinus (philippinus, salvadorii)

M. ornatus

M. apiaster

M. leschenaulti

M. malimbicus

M. nubicus (nubicus, nubicoides)
A REVIEW OF THE BIRDS OF GIBRALTAR AND ITS SURROUNDING WATERS
Authors: Lathbury Gerald
Published: April 2008

In compiling this new list, which is based on Howard Irby's ‘Ornithology of the Straits of Gibraltar’ (1895) but is confined to the area of Gibraltar itself and its surrounding waters, the results of three years' observations from 1965 to 1968 together with other recent records and literature have been used. Of the 198 species listed 118 are passage migrants and a further 36 winter visitors. The introductory sections of the paper contain a short description of the climate and topography of Gibraltar showing why the Rock can support only a small number of breeding species and why so few water birds find a place in the list. A few general observations and tentative conclusions on the migration of soaring birds and passerines in relation to weather conditions, particularly wind direction, are included as a background for the large number of passage migrants which figure in the list.
NOTES ON THE BIRDS OF EASTER ISLAND
Authors: Johnson A. W. , Millie W. R. , Moffett G.
Published: April 2008

Information on the occurrence and breeding status of sea‐birds at Easter Island has long been scanty and incomplete. In order to obtain accurate information and in particular to investigate reports of a supposed breeding site of a “brown‐plumaged petrel”, we spent three weeks on the island, including 12 days camping out on the uninhabited, waterless islet of Motu‐Nui.

The petrel proved to be the Christmas Island Shearwater Puffinus nativitatis, whose breeding range is thus extended by nearly 2,000 miles. Ten other species of sea‐birds were definitely identified and specimens, photographs and breeding records were obtained for most of them. It is shown that the bird species frequenting Easter Island are, like the human inhabitants, predominantly of Polynesian origin—in fact the American continents are not represented at all.

The paper opens with a brief outline of present‐day conditions on the main island, and concludes with an account of the “bird‐cult” rituals which are known to have been a feature of life in Easter Island for centuries.
THE SNARES ISLANDS PENGUIN EUDYPTES ROBVSTUS
Authors: Stonehouse Bernard
Published: April 2008

Recent visits to the Snares Islands (48o S, 166o E), 96 km south‐southwest of Stewart Island, New Zealand, have yielded new information about the endemic crested penguin Eudyptes robustus (Plate 1(a)). This paper, based on visits by University of Canterbury‐teams in January and February 1961 and 1967, discusses nomenclature and taxonomy, diagnostic characters, egg size, sexual dimorphism, and the dimensions of fledglings, yearlings and adult birds.

The Snares Islands Penguin Eudyptes robustus breeds only on the Snares Islands and is repro‐ductively isolated from Fiordland Penguins, which are its closest kin. Both adults and yearlings of the two species are morphologically distinguishable, although measurements from museum skins stress similarities rather than differences between the species. Measurements of live chicks, yearlings and adults show that chicks reach independence with feet and flippers almost fully grown; adult body length is achieved during the first year, and the large bill characterising the species develops subsequently. Breeding times differ from those of Fiordland penguins. There is a strong suggestion that, within normal clutches of two eggs, one is 20% smaller than the other and has reduced chances of survival.
THE NIGHTLY INITIATION OF PASSERINE MIGRATION IN SPRING: A DIRECT VISUAL STUDY
Authors: Hebrard James J.
Published: April 2008

The nightly initiation of migration of passerine birds was studied during a spring season in coastal Louisiana. A horizontally‐directed portable ceilometer placed on a tower illuminated birds as they took off from or landed in the trees. Daily censuses were conducted to supplement nocturnal observations. Local weather conditions were continuously monitored at the site of the study.

Appreciable numbers of migrants landed in the woods on the coast almost every day, the first birds usually appearing between 10.30 and 11.00 hrs, and the last about 16.00 hrs. On two occasions birds were seen landing after dark. The migrants usually became quiet by about 18.00 hrs and the first bird was usually seen leaving the trees just over an hour later. The exodus usually peaked between 19.10 and 19.15 hrs, 40 to 45 minutes after sunset.

The time of initiation of nocturnal migration was not significantly affected by immediate weather factors. The duration of the exodus varied widely, and was related to the number of individual birds in the census area.

On some occasions grounded migrants stayed overnight, but only when there had been an active cold front over the Gulf. No local weather conditions examined were found to be directly inhibitory to nocturnal migration.

Birds departed singly and without preliminary activity. Wind direction influenced the initial orientation of the migrants. With southerly winds, 57% of the birds seen flying across the beam initially headed toward the Gulf, while with northerly winds only 19% initially flew in this direction.
SEA‐BIRD OBSERVATIONS OFF SOMALIA
Authors: Bailey R. S.
Published: April 2008

The oceanography of the coastal waters of eastern Somalia was investigated by R.R.S. ‘Discovery’ during August and September 1964. The oceanographic findings are briefly described. Although upwelling was in progress north of 8oN, plankton, sea‐birds and other signs of a high rate of organic production were notably scarce.

Previous knowledge of the marine ornithology of the Somali coast is poor and some unpublished notes ot ine late M. E. W. North are given in full.

In 1964 both the warm Somali current and the upwelling area between Ras Mabber and Cape Guardafui supported few sea‐birds, though they were largely different species. The only area with abundant sea‐birds was at the boundary between the cool upwelled water and the warm water spreading from the Gulf of Aden. It is suggested that the former may sink before the final stages of the ecological succession are reached, so that food for sea‐birds is scarce.

Summaries of the distributions of each species are given and these are compared with previous observations.
LIFE HISTORY OF THE BRIGHT‐RUMPED ATTILA ATTZLA SPADZCEUS
Authors: Skutck Alexander F.
Published: April 2008

An adaptable and highly variable species, the Bright‐rumped Attila ranges across the whole breadth of tropical America and from sea level up to 6,000 or 7,000 feet. It inhabits not only rain forests and deciduous woodland but often enters plantations and clearings with scattered trees. It is usually seen alone, high in the trees.

Its diet includes insects, small lizards, tiny frogs, fruits, and arillate seeds. Sometimes it catches small creatures from pasture grass or low weeds in plantations. Occasionally it forages with army ants.

Both sexes deliver clear, melodious, far‐carrying songs or calls, in Costa Rica chiefly from February to April.

A nest found in the Caribbean lowlands of Costa Rica was a bulky open cup, situated 32 inches above the ground on a little shelf in the deep embayment between two high plank buttresses of a great tree at the edge of a cacao plantation. In 1967 this nest held four nestlings that flew on 24 April. A new nest built in the very same site in the following year contained four newly laid eggs on 13 March. They resembled the eggs of certain American flycatchers more than those of other cotingas.

Only the female incubated. During an all‐day watch, her sessions ranged from 63 to 111 minutes, her recesses from 13 to 60 minutes, and she covered her eggs for 67% of the time. When she returned to her nest she was escorted closely by her mate. While sitting, she often sang a long‐drawn, subdued nest song, or in a louder voice answered her mate with a song similar to his. The incubation period was no less than 18 days.

Newly hatched nestlings had flesh‐coloured skin shaded by dark grey down that was abundant for a passerine. The interior of the mouth was bright orange‐yellow. Even before they were feathered, these nestlings gave weaker‐voiced imitations of their parents' calls or songs, and soon they could reproduce much of the adults' repertoire. The nestling period was about 18 days.

Only the female brooded the nestlings, but the two parents took about equal parts feeding them, chiefly with small lizards, tiny frogs, and a few insects, brought one at a time in the parents' bills.

The parents defended the territory around their nest, vigorously attacking intruders of their own species.
THE FLYING ABILITY OF ARCHAEOPTERYX
Authors: Yalden D. W.
Published: April 2008

Estimates for the wing span, mass and wing area of Archaeopteryx lithographica are provided, and these are used to derive certain of the flight parameters. From the data available on the lengths of skeletal components, amplified by examination of casts of the specimens and full‐size enlargements of photographs, the wing span is estimated at 58–59 cm and the wing area as 479 cm2. To judge from animals of similar size, the mass was probably about 200 g. These figures give an estimated minimum flying speed of 7‐6 m/sec and a wing loading of 0–42 gf/cm2. These figures are, and must be from their method of derivation, comparable with those of similar sized modern birds,

These data are used to reconsider the possibility of flapping flight in this bird. It is suggested that the primitive anatomy of the pectoral skeleton has been somewhat over‐emphasized, and it is shown that the pectoral crest on the humerus was relatively very large compared with modern birds. The power required to fly would require muscular physiology outside the range of mammalian (at least, human) capability, but well within the modern avian range. It is felt that Archaeopteryx was capable of flapping flight, but that it was probably not long sustained.
LEARNING AND THE FORAGING PERSISTENCE OF WHITE‐CROWNED SPARROWS ZONOTRICHIA LEUCOPHRYS
Authors: Simons Spencer , Alcock John
Published: April 2008

Ten White‐crowned Sparrows Zonotrichia leucophrys took part in an experiment of 24 trials in which they foraged for food hidden in one of four blocks. Each block had six depressions covered with sunflower seed shells. On each trial three of the blocks were empty while one contained six sunflower seed particles. Initially the birds removed most of the covers from the empty blocks as well as from the baited blocks. However, as the experiment progressed, many of the birds learned to displace only a few covers from the empty blocks they encountered before leaving to search for the block with sunflower seeds. In other words, the sparrows proved capable of learning to adjust the time spent foraging in areas of identical appearance on the basis of the results of their initial “test” pecks. The ability to alter foraging persistence on the basis of test probes could contribute to the efficient exploitation of hidden food by bird predators.
EFFECT OF AGE ON THE FISHING ABILITY OF SANDWICH TERNS STERNA SANDVICENSIS
Authors: Dunn Euan K.
Published: April 2008

The fishing ability of first‐winter and older Sandwich Terns was compared at foraging sites used by both age‐groups on the coast of Sierra Leone between January and March 1970 when first‐winter birds were about 7–9 months old. The methods used for measuring various parameters of fishing ability are described. It was found that a significantly larger proportion of plunge dives by the older age‐group yielded prey although the difference between the two age‐groups was only slight.

There were no major differences between the age‐groups in diving rates or in size of fish captured. Older birds tended to dive from higher than first‐winter birds.

By driving shoals of small fish to the surface, predatory fish enhanced the fishing success of both age‐groups on certain days. Where man's beach seining operations yielded a superabundance of small fish near the tideline, these were captured equally well by both age‐groups.

First‐winter birds were not seen being fed by older birds, and although food‐begging behaviour was observed once in late January it is clear that the first‐winter birds were self‐sufficient for food by the time this study was made.

Some implications of the observed differences in fishing success are discussed. It is suggested that, after fledging, Sandwich Terns gradually gain the judgment and skill necessary to dive profitably from increasing heights and so learn to exploit prey in a greater range of water depth as they get older.
SOCIAL STIMULATION OF REPRODUCTION IN HERRING AND LESSER BLACK‐BACKED GULLS
Authors: MacRoberts Barbara R. , MacRoberts Michael H.
Published: April 2008

The date of the first egg laid and the position of nests were recorded for all pairs in 10 study areas within the mixed Herring and Lesser Black‐backed Gull colony on the southern end of Walney Island, Lancashire. The study areas differed from one another in density of breeding birds and in proportion of each species. These data were collected in order to determine if evidence could be found for synchrony of reproduction by social stimulation (the “Fraser Darling Effect”). The gulls in different study areas showed considerable variability in onset and spread of laying; however, attempts to correlate a number of variables, such as density of breeding birds in each area with median date or spread of laying, average nearest neighbour distance with median date of egg‐laying, and median laying date for one species with that of the other species in the same section of the gullery, failed to produce convincing evidence for inter‐ or intraspeciiic social stimulation of reproduction.
FLOCKING AND FEEDING IN THE GREAT TIT PARUS MAJOR–AN EXPERIMENTAL STUDY
Authors: Krebs John R. , MacRoberts Michael H. , Cullen J. M.
Published: April 2008

Some aviary experiments designed to investigate the survival value of flocking in the Great Tit Parus major are described.

An individual searching for a source of food is less likely to find it if he is on his own or in a pair than when in a flock of four. This is a result of local enhancement: with more pairs of eyes searching, some member of the flock is likely to come across the food sooner than would a lone bird, and once one finds the food, others in the flock more or less immediately assemble at the food source. Once the birds have found a source of food, dominance interactions play a role in determining which individuals obtain the most food.

If one bird finds a single item of food, both it and the other members of the flock rapidly alter their searching behaviour, concentrating their attention in the general area and /or type of place where the food item was found.

Even if a bird searches in a place and does not find food, the others in the group show some increase in searching effort in the same area or type of place. The extent to which they do this depends on whether they are used to finding food in clumps or dispersed.

The relevance of these findings to birds in the wild is discussed. It seems likely that local enhancement does occur in natural flocks, and the flocking in Great Tits is of benefit to the participants because they increase their effectiveness in finding food. However, the question of the survival value of mixed‐species flocks of titmice remains unresolved.
THE WINTERING AND MIGRATION OF PALAEARCTIC PASSERINES AT KAMPALA, SOUTHERN UGANDA
Authors: Pearson D. J.
Published: April 2008

Palaearctic passerines were observed and trapped over three seasons near Kampala, in southern Uganda. Passage migration and wintering are described.

Only 11 species were encountered at all frequently. Three of these were common as passage migrants only, the rest remained in numbers throughout the northern winter. Most migrants reached Kampala during October and November, but the majority of Acrocephalus warblers appeared later. Spring departure commenced at the end of March, and continued throughout April. Autumn passage was in progress from late September to December, but appreciable spring movement was confined to a period of a few weeks only.

Ringing revealed that most wintering warblers were highly sedentary, and that a high proportion of surviving birds returned to the same site in successive winters. No fewer than 12–5% of the 220 Acrocephalus warblers ringed during 1966/67 were retrapped during the following season.

Wing measurements were recorded for most migrants trapped. Plumage details were noted, and representative specimens of several species were subsequently compared with museum series. It was concluded that most migrant passerines which occurred at Kampala were of eastern origin.

Migration times were compared with those recorded for some other areas. The spring movement from southern Uganda to the Middle East tends to be more rapid than the return journey. Some species apparently spend weeks or even months of the autumn in northeast Africa before reaching the equator,
THE BIOLOGY OF THE WAVED ALBATROSS DIOMEDEA IRRORATA OF HOOD ISLAND, GALAPAGOS
Authors: Harris M. P.
Published: April 2008

As a nesting species, the Waved Albatross Diomedea irrorata is restricted to Hood Island in the Galapagos archipelago where 12,000 pairs bred in 1971. Outside the islands the species occurs over the northern parts of the Humboldt Current.

Two colonies were studied in detail (1970–1971). At the start of a season, males returned first to the colonies and defended a small territory. Copulation occurred without any elaborate ceremony and the female spent little time on land before laying. There was no fixed nest‐site, even within a season, and birds moved their eggs considerable distances. This resulted in heavy egg losses. Younger birds bred later than older birds and laid longer but narrower eggs. The average incubation spell varied from four to five days at the extremes of the incubation period to 19 days in the middle. The average incubation and fledging periods were 60 and 167 days respectively. Pairs which lost an egg sometimes adopted the abandoned egg of another bird and successfully reared the chick. Most pairs nested in both seasons.

Nesting success was extremely variable, both between years and between colonies. Between 1961 and 1971 at Punta Suarez, virtually no young were reared in four seasons. Even in 1970–71, where nesting success was good, some groups of birds deserted their eggs en masse whereas in neighbouring areas up to 80% of the pairs reared young.

The main foods of the young were squid and fish.

Birds did not moult wing and tail feathers at the breeding colonies, and about 50% retained some primaries for more than one season, suggesting that successful pairs had difficulty in fitting in a complete moult between breeding attempts. Old feathers were normally found among the inner primaries and at the next moult were preferentially replaced, though adjacent newer feathers were sometimes retained for another season.

Some birds bred in their fourth years, but most not until a year or two older. Immatures were present at the colonies late in the breeding cycle, the youngest returning latest and remaining until the last young fledged.

Survival of adults and young averaged at least 95% and 93% per annum over many years. Adults and young ringed in 1961 survived equally well.

The significance of the timing of the return of immatures and of the large‐scale desertion of eggs, apparently not due to food shortage or disturbance, is discussed.
SURVIVAL OF MANX SHEARWATERS PUFFINUS PUFFINUS
Authors: Perrins C. M. , Harris M. P. , Britton C. K.
Published: April 2008

The breeding success of Manx Shearwaters at Skokholm Island, Pembrokeshire, was followed in study burrows, and data on survival of the young were augmented by ringing large numbers as they were about to leave the island and recapturing them in later years.

The weight of the young at fledging and the date at which they leave affect their chances of survival; overall, as many as 30% of the young birds may survive to reach breeding age, which is thought to be normally about 5–6 years. Adult mortality varies between wide limits of about 5 and 20%, but juvenile survival appears to be of about the right order to balance adult losses.

The significance of the one‐egg clutch is discussed. At the normal time of laying the female may not be able to obtain sufficient food to form a second egg. A two‐egg clutch, laid at a later date, would not produce more surviving young since these would fledge too late in the season to have a good chance of survival.

The advantage of leaving the island at a heavy weight is discussed, and it is concluded that the fat stores laid down give heavy young a greater chance than light young of migrating a long distance without food. It is possible that the young may even reach their winter quarters (off Brazil) without having to feed on passage if they depart with enough stored fat.
BIRDS ON GRENADA
Authors: Lack David , Lack Andrew
Published: April 2008

Resident and transient birds seen on Grenada in 1971 are listed. Leptotila wellsi still persists. Apus apus is new for the West Indies. Nearly half the resident land birds are regular in both lowlands and highlands.
BREEDING ECOLOGY OF TURNSTONESARENARIA INTERPRESAT HAZEN CAMP, ELLESMERE ISLAND, N.W.T.
Authors: Nettleship David N.
Published: April 2008

Turnstones arrive on Ellesmere Island in late May or early June. Pair‐formation takes place during migration, or after arrival in courtship groups along the beaches, or on the nest territory, depending on weather conditions. Pair‐formation was not observed at Hazen Camp in 1966 as most birds were already paired when observations began on 3 June. The preferred nesting habitat wasDryas‐hummocked tundra closely associated with a marsh, stream, or pond. A census area of 240 ha supported 13 breeding pairs, possibly 14; the total number of pairs breeding in the Hazen Camp study area was estimated to be 70 (3.04 pairs/km2). Egg‐laying began on 10 June, with 46% of the first eggs laid 13–15 June. 62% of the sets were completed between 19 and 21 June. Both sexes incubated, the female regularly and the male sporadically. Hatching was also well synchronised; most clutches hatched between 7 and 14 July. Nest success was high (79%). After hatching territories dissolved and family groups moved freely over the tundra, concentrating at ponds where food was readily available for the young. Both adults attended the young during the pre‐fledging period, but the females apparently departed long before the young fledged. Males left once the young could fly and the adult fall migration was complete by early August with the exception of late breeders. Most of the young departed in the second half of August. Fall migration is complete by late August or early September.

The breeding season appears to be timed so that the young are raised when food is most abundant. Food supply (dipterous insects, especially adult chironomids) was highest from 8 to 12 July at the peak of the hatching period. While food supply for the young declined during the growing period, the early departure of half the adult population, and family movements over the tundra, appeared to reduce the food demand correspondingly.

Food appeared to influence the distribution of breeding pairs markedly, restricting them to the vicinity of marshes, streams, and ponds. Territoriality displayed by Turnstones is believed to be closely associated with the protection of the nest against predators and adult food requirements during incubation; it also seems likely that territory has at least a local effect in regulating the number of breeding pairs.
THE WINTER FEEDING ECOLOGY OF WIGEON AT BRIDGWATER BAY, SOMERSET
Authors: Owen Myrfyn
Published: April 2008

The feeding ecology of Wigeon wintering in the vicinity of Bridgwater Bay National Nature Reserve is described. The birds roost on mudflats in the Bay during the day and feed, mainly at night, on saltings and wet pastures in the surrounding area. Their food, ascertained from gut analyses, consists largely of grass leaves; with roots, stolons, bulbils and seeds of secondary importance. Analyses including gizzard contents much exaggerated the importance of seeds because they are retained in the gizzard for longer than softer items.

An investigation of Wigeon feeding behaviour and food preferences on salting pasture is described, using the density of the birds' droppings on different vegetation zones to assess usage, and faecal analysis to determine the composition of the selected diet. The technique of faecal analysis is discussed in relation to feeding studies on grazing wildfowl.

Disturbance is a very important factor affecting the availability of feeding habitat, and this can mask the birds' food preferences. Early in the winter, Wigeon select Puccinellia maritima in preference to Agrostis stolonifera and Festuca rubra. They do this initially by selecting the broad zone in which they feed, by selecting feeding sites within zones, and particular plant species from a mixed sward. The birds are more selective when feeding in less preferred zones. The mechanisms and reasons for food selection are discussed in relation to characteristics of the habitat and of the plants. It is concluded that the nutritional value of the plants is important in determining the birds' preference, but that other factors also play a part.

Wigeon are flexible in their feeding habits and are increasingly found on inland habitats. They are adaptable in using new roosts, and in modifying their behaviour in response to changes in food supply and changes in disturbance pressures.
SURVIVAL, PAIR BOND RETENTION AND NEST‐SITE TENACITY IN BULLER'S MOLLYMAWK*
Authors: Richdale L. E. , Warham John
Published: April 2008

Adult Buller's Mollymawks Diomedea bulleri banded in 1948 and 1961 at the Snares Islands south of New Zealand have been recovered between 1961 and 1971. Survival curves are presented which indicate the existence of a constant annual mortality rate of not more than 11.1 % with a mean expectation of further life at the time of banding of not less than 8.5 years.

Breeding birds show a strong tendency to retain both the pair bond and the nest‐site. One pair was still breeding in 1971 at the same nest at which it bred 23 years earlier. No re‐matings were recorded while the original partner was known to be still alive.

The dimensions of eggs laid over the years by particular females are presented. These enable some general indications to be given of the effects of the age of the female on the dimensions of the eggs which she lays.
A NEW SUBSPECIES OF ACROCEPHALUS BAETICATUS FROM LAKE CHAD AND A TAXONOMIC REAPPRAISAL OF ACROCEPHALUS DUMETORUM
Authors: Fry C. H. , Williamson K. , Ferguson‐Lees I. J.
Published: April 2008

A new population of African reed warblers, Acrocephalus baeticatus hopsoni, is described from Lake Chad. Its characters, together with those of unallocated material from Senegal, Eritrea and Tibesti, are intermediate between the Palaearctic A. dumetorum and other races of A. baeticatus. It is concluded that dumetorum is conspecific with A. baeticatus, and by priority becomes A. baeticatus dumetorum. The merits of A. palustris, A. scirpaceus and Hippolais pallida for inclusion in an A. baeticatus superspecies are considered, but allow no firm conclusion.
ADAPTATION IN THE GENUS PHYLLOSCOPUS
Authors: Gaston A. J.
Published: April 2008

The paper describes variation among species of the genus Phylloscopus in weight, relative wing‐, tail‐, tarsus‐, and bill‐length, tail/wing ratio and degree of roundness of the wing, wing formula, emargination, and plumage colour. This variation is compared with differences in niche preference within the genus, and relationships between niche, feeding strategies, and morphology are suggested. It is concluded that evolution within the genus has taken place mainly through the development of different feeding strategies, to suit the structural properties of different niches, without altering the range of size of the prey. The genus Sylvia is treated briefly in order to provide comparison, and other genera of Sylviinae are discussed where parallel adaptation seems likely.
THE PROBLEM OF CHICK LOSS IN THE SOUTH POLAR SKUA CATHARACTA MACCORMICKI
Authors: Procter Dennis L. C.
Published: April 2008

Hunger releases the aggressive behaviour commonly shown by the first chick of the two‐chick brood of the South Polar Skua Catharacta maccormicki. Hunger also releases aggressive behaviour in the second chick, but asynchronous hatching usually restricts this behaviour to the first chick.

The degree of hunger experienced by the first chick regulates the intensity of its aggressive behaviour, which in turn affects the second chick's survival. Aggressive behaviour restricts the second chick's access to the nest area and deprives it of parental attention, increasing its susceptibility to starvation, exposure and predation.

Weight and age differences between the chicks affect neither the release of aggressive behaviour, nor the survival of the second chick.