bluuebunny/crossref_metadata_2025_split huggingface dataset:
PHOTOPERIOD AND THE REFRACTORY PERIOD OF REPRODUCTION IN AN EQUATORIAL BIRD, QUELEA QUELEA
Authors: Lofts B. 
Published: April 2008

SUMMARY

In a number of avian species in which testicular development can be evoked by increased daily photoperiods, it has been found that such development cannot be sustained indefinitely and that there is a period following each breeding cycle during which increased daily photoperiods are ineffective. This is the refractory period.
Gametogenesis ceases during this phase and its duration plays a critical role in the timing of the breeding cycles. The duration varies from species to species and in most temperate birds lasts some four months.
Some authors claim that the whole of the avian breeding cycle is under photoperiodic control and that the duration of the refractory period is determined by variations in daylength, short days dispersing it and long days prolonging it.
When the equatorial weaver finch, Quelea quelea, was placed under a 17‐hour daylength, the internal rhythm of reproduction was accelerated and the birds quickly passed into a premature refractory period.
During the refractory phase three weeks of short 8‐hour daylengths followed by a 17‐hour photoperiod had no effect on the duration of the refractory period, and birds displayed a recovery of spermatogenetic function at the same time as those maintained under a continuous 17‐hour photoperiod. In each case the refractory period lasted six weeks.
Birds maintained under an equatorial daylength of 12 hours also entered a refractory period and, again, pretreatment during the refractory period with shortened lengths of 11·25 hours had no effect on its duration.
Quelea which were maintained under a constant photoperiod of 11·25 hours during their refractory period showed a recrudescence of gametogenesis six weeks later, but under an 8–hour daylength the gonads remained regressed to the end of the experiment.
It was concluded that in this equatorial species a semi‐autonomous internal rhythm of reproduction operates and the refractory period is independent of photoperiodic fluctuations. There was no evidence of a premature dissipation of this period by a reduced photoperiod, nor was there a prolongation of refractoriness by long daylengths.
THE DISTRIBUTION OF BIRDS IN NORTHEAST GREECE IN SUMMER
Authors: Raines R. J. 
Published: April 2008

SUMMARYThe results of two expeditions to northeast Greece in May 1960 and 1961 are described together with records of a number of other parties of ornithologists who have recently visited the area. Observations include the first recorded breeding of Spur‐winged Plover Hoplopterus spinosus and Isabelline Wheatear Oenanthe isabellina in Greece, and of the Fan‐tailed Warbler Cisticola juncidis in north Greece; also the first recorded occurrence of Knot Calidris canutus and Spectacled Warbler Sylvia conspicillata in Greece. In the systematic list many discrepancies with previously published data are recorded for this relatively remote and ornithologically little known area of Greece. Observations are made on 111 species out of 219 recorded and on the migration observed.
MIGRATION ACROSS THE SOUTHERN NORTH SEA STUDIED BY RADAR PART 4. AUTUMN
Authors: Lack David 
Published: April 2008

Summary.

In autumn in Norfolk, the main nocturnal departures are (i) S.S.E., especially in September, of British summer residents; (ii) E., of unknown species; (iii, iv) S.S.W. and W., chiefly in October, the onward passage of birds, mainly thrushes, arriving in these directions from over the sea. Rarely, there are small northward movements. The main diurnal departures are (i) S.E., chiefly from mid‐September to mid‐October, of British summer residents; (ii) W., chiefly in October, the onward passage of diurnal migrants from Holland.
The main immigrations are (i) S.S.W. from Norway, chiefly of chats, warblers, flycatchers and arctic waders in September, and of thrushes in October; (ii) S.S.E. from northern Britain, chiefly in September, of British summer resident night‐migrants drifted off‐shore by westerly winds; (iii) W. by both day and night from Holland, mainly of Lapwings and small night‐migrants in September and of Starlings, Chaffinches, thrushes and Lapwings in October; (iv) both nocturnal and diurnal migrants heading W.S.W. from Denmark, when drifted south by northerly winds, of the same species as in (iii).
All 9 nocturnal and 4 diurnal movements analysed were far commoner and denser with following than opposed winds. They occurred with cross and opposed winds mainly when the wind was light. They tended to be commoner in clear than cloudy weather, and in anticyclonic than disturbed weather. After allowing for wind‐direction, they were equally common in warm and cold weather.
Small passerine night‐migrants leaving England S.S.E. must change their heading to southwest somewhere around the south of France. Arctic waders arriving S.S.W. must have changed their heading in Scandinavia from one much further to the west.
Norwegian thrushes change their heading from S.S.W. to S.S.E. when over the sea after dawn, provided that they have also been drifted by easterly winds, but they change back to S.S.W. over the land.
THE BEHAVIOUR OF THE WILLOW WARBLER PHYLLOSCOPUS TROCHILUS IN CONTINUOUS DAYLIGHT
Authors: Brown R. G. B. 
Published: April 2008

Summary.Willow Warblers Phylloscopus trochilus at Wytham, Oxford (51° 46' N., 1° 15' W.), start to sing around sunrise, in late April to early June. In the continuous daylight at Neiden, East Finnmark (69° 42' N., 29° 25' E.), they do not sing all the time, but in late June to late July start singing between 22.45 and 01.45 hrs., the start becoming progressively later as the season draws on. At Neiden, nest visits start some time after song (01.00–02.30), and this is probably also true at Wytham.The influence of environmental variables on the starts of the two cycles is discussed. It is concluded that song starts at Wytham when light intensity has risen above a certain threshold level, and at Neiden, when it has reached a minimum value or has started to rise again. It is suggested that the Neiden birds react to the closest approximation of their light intensity cycle to that at dawn further south. The end of daily song at Neiden may be controlled by internal factors. It is suggested that the start of the Neiden nest‐visit cycle is controlled by light intensity, but modified by temperature effects. The possibility that the environment affects the bird indirectly, via its brood or food, can be ruled out. The functional significance of the retention of activity lulls in the continuous daylight of the Arctic summer is discussed.The daily song‐starts of the Garden Warbler Sylvia borin, Brambling Fringilla montifringilla, and Yellowhammer Emberiza citrinella, follow the same pattern as those of the Willow Warbler. The Redwing Turdus musicus often has no daily song lull; its nest‐visit lull begins and ends well before midnight. The significance of this is discussed.
THE BREEDING BEHAVIOUR OF THE SOUTH POLAR SKUA CATHARACTA MACCORMICKI
Authors: Young E. C. 
Published: April 2008

Summary.At Cape Royds a small number of skua pairs nested at the penguin rookery and prevented other skuas from gaining any food there. Their territories were similar to those of the other pairs nesting near the rookery but which fed at sea. The birds occupied territories here from about mid‐November until early March.The first eggs were laid on 27 November and most were laid by the second week of December. Most hatched after 28–29 days incubation and all hatched within a narrow range. Male and female alternated at the nest, sharing incubation fairly evenly. Nest changes occurred at intervals of 1 1/2–3 hours. In pairs feeding at sea, the female is fed by the male during incubation.Chicks first flew when 49–59 days old but were fed by the parents for some time after this. Chicks fed on fish grew as rapidly as rookery chicks fed on penguin flesh, attained a heavier weight and grew more evenly. Length increase in primary feathers was a more useful index of growth than was gain in weight. It more nearly approached a linear relation with age and was not affected by fluctuations in feeding.Desertion and over‐cooling accounted for most of the eggs lost.Chick‐mortality fell within three categories: loss of the younger chick of the pair; loss of the older chick, or of a single chick after a period of slow growth“, loss of a single chick during normal growth. Most younger chicks were soon chased from the nest by the older chick and were killed later by cold or by adult skuas (a few were maintained by the parents for a short period away from the nest area). Only one pair reared two chicks to fledging; in other nests the older chick invariably survived longer. No chicks were lost on the territories after January.Only a small number of adult birds in any colony killed chicks and even these were only active if confined to their territories, and not able to feed at sea, through bad weather. No parents were seen killing their chicks but some ate their chicks and may have first killed them. There were numerous instances of birds adopting chicks or not harrying them. Non‐breeding birds were not important predators.The breeding success of pairs in different colonies varied from 0 to 38·5 % and averaged 23·2 % which is lower than that recorded in most other studies. Highest mortality was in territories outside colonies. This appeared to be correlated with a greater proportion of inexperienced birds in these situations. More chicks survived from rookery pairs than non‐rookery pairs. Feeding at the rookery allows both birds to be more often on the territory and there is less likelihood of food shortage during early chick‐rearing.The loss of one chick of the pair is related to the low tolerance to starvation of the older chick: a temporary food shortage causes it to chase the other from the nest area.
A COMPARATIVE ANALYSIS OF NEST STRUCTURE IN THE WEAVER BIRDS (PLOCEINAE)
Authors: Crook John Hurrell 
Published: April 2008

Summary.Ploceine nests are small globes with entrances at the side or below, with or without some extension into a spout or tube. The fabric of the nest is often remarkably strong and pliant.Nine main variables of structure and construction in the nests of 62 species are listed and discussed. The paper includes the first account of the remarkable nest construction behaviour of Malimbus rubriceps in which nest material is “prepared” for use in building before the bird takes it to the nest.Correlations are found between nest shape, materials used in construction, methods of attachment, stitching and fabric, and nest‐sites. The correlations reveal four fundamentally different modes (A‐D) of structural organization, divisible into nest‐types specialized to particular sites. A classification is provided.The survival values of nest characteristics are analysed in relation to weather, predation and inter‐individual competition for materials. Fabric and lining are considered products of environmental selection, the stronger fabrics occurring in sites imposing greater stress. The roofing layer (which is correlated with tube loss) of many African colonial savannah birds is an adaptation to rain shedding. An alternative adaptation to rain occurs in Ploceus philippinus in India and consists in thickening the nest wall by excessive stitching on the exterior throughout nest occupation. This also correlates with the remarkable abilities of the species to repair its nest, in part an adaptation to the stealing of nest materials by neighbours.The direction of evolutionary change in nest structure is considered. Shifts in type of nest‐site expose the structure to new interactions with environment and predation to which the resultant nest is an adaptive compromise. Discussion of the range of nests as a whole is complicated by cases of convergence and ignorance concerning the precise origin of the sub‐family. In general the strong fabric and suspended nest mark a major advance on the simple structure found in other Ploceidae. These features allow the adoption of sites providing additional security from predators. Modes A and D are held to be primitive; but while A has proved adaptable to many environmental circumstances and has given rise not only to four nest‐types but also to both Modes B and C., Mode D occurs only in a small group of birds successful within a restricted niche in Africa.
MIGRATION IN IRAQ
Authors: Marchant S. 
Published: April 2008

Summary.Migration in Iraq is discussed on the basis of three years' experience supplemented by data from other unpublished sources and the literature.The migration of certain passerine and near‐passerine species is considered, particularly as regards comparative numbers seen in spring and autumn, and the question of their passages between breeding quarters in the Palaearctic and winter quarters in Africa, in relation to weather, geography and ecology of the Middle East. Of about 50 species discussed, half are clearly more abundant in spring, and most of the rest probably are; thus supporting the idea that such species in autumn may make longer unbroken flights than in spring. For a number of these species the nearness of the breeding quarters to Baghdad is stressed.Exceptions are Streptopelia turtur, Alaudidae, hirundines and perhaps Motacilla flava, which are prominent, and even the only, visible daylight migrants among such small birds. These cross Iraq from east to west in autumn in vast numbers and are thought to migrate round the Fertile Crescent past Damascus, rather than fly direct towards Africa. Comparisons are made with the Mediterranean region and the rest of the Arabian peninsula, and some comments are added on the matter of broad‐front and narrow‐front migrations.In an appendix the most important aspects of migration of large non‐passerine birds in Iraq are discussed.
SUB‐FOSSIL BIRD REMAINS ON ASCENSION ISLAND
Authors: Ashmole N. P. 
Published: April 2008

SUMMARYBird bones and feathers found in phosphate deposits and fumaroles on Ascension during the B.O.U. Centenary Expedition were used to supplement the historical records in building up a picture of the original avifauna of the island. The remains which can be definitely identified provide strong circumstantial evidence that the sea‐bird colonies on the main island included at least the following species: Oceanodroma castro, Phaethon aethereus, Sula sula, S. dactylatra, Fregata aquila and Sterna fuscata: a skull apparently of Gygis alba was also obtained. No remains definitely referable to Phaethon lepturus, Sula leucogaster or Anous stolidus have yet been found, but it seems very likely that these species also nested in numbers on the main island of Ascension, while Anous tenuirostris, which still nests on the cliffs of the main island, doubtless also did so in the past.In addition to sea‐birds, a skull and a tarso‐metatarsus of a small rail, found in separate localities, probably represent the extinct flightless species described by Peter Mundy. The rail whose bones were obtained is provisionally considered as a new member of the genus Rallus.The only surviving species that is endangered locally is the Red‐footed Booby Sula sula: the history of this species on Ascension is discussed.
EGG DIMENSIONS OF SOME ASCENSION ISLAND SEA‐BIRDS
Authors: Stonehouse Bernard 
Published: April 2008

SUMMARYThe lengths and greatest diameters of over 2,000 eggs of ten species of sea‐birds were measured on Ascension Island and off‐lying stacks; some eggs were also weighed. Means with standard deviations and extreme measurements are presented, together with brief descriptions and a short discussion of egg shape, size, and variability within and between species.
NOTES ON ECUADORIAN BIRDS
Authors: Lévêque Raymond 
Published: April 2008

SummaryOccasional observations were made during 1960–62 mainly around Quito and Guayaquil, to supplement the works of Chapman (1926) and Marchant (1958). Three species are mentioned for the first time from western Ecuador and one from the Amazonian side; 34 North American migrants were seen. Data are provided for several tropical species ranging up to the Sierra. The existence of a large mixed heronry on the Guayas is also mentioned.
THE PECKING RESPONSE OF YOUNG ARCTIC TERNS STERNA MACRURA AND THE ADAPTTVENESS OF THE “RELEASING MECHANISM”
Authors: Quine D. A. , Cullen J. M. 
Published: April 2008

SummaryExperiments were made using models to analyse the stimuli evoking the pecking behaviour of young Arctic Terns, with comparative tests on Herring Gulls in one year. Some of the findings for the Arctic Tern may be summarized as follows. The chicks pecked at red, blue and silver more than at orange, yellow, green, black and white, and the response was increased by adding a contrasting spot to a beak. A plain red beak, the natural colour in the breeding season, was pecked less than one tipped with black, the colour in the winter. Chicks responded more to the beak models when a “fish” was attached (Fig. 1). Under natural conditions the chicks swallow their food, chiefly the sandeel Ammodytes, head first, and this is facilitated by the chicks pecking more at the head than the tail end of the fish. The stimuli by which head and tail are distinguished were found to be the pattern of the eye and tail‐fin rather than the shape of head and tail.The view that the selectiveness of the tern chicks is adapted specifically to the feeding situation is discussed critically, using the comparative results from the Herring Gull tests, and it is argued that while this is not the case for some of the stimuli effective in evoking the pecking (e.g. movement), whose adaptive significance concerns the general efficiency of the eye, it could well be responsible for some of the selectiveness found (e.g. high response to blue, low response to tail‐fin patterns). Comparison of the two species suggests that the Arctic Tern is specially adapted to respond to fish‐like objects attached to the beak. In the Herring Gull the ability to distinguish the head and tail of a fish appears to anticipate the time when the chick requires it.
THE BREEDING BIOLOGY OF THE SHELDUCK TADORNA TADORNA
Authors: Hori John 
Published: April 2008

SummaryBreeding biology of Shelduck was studied in England on the Isle of Sheppey, Kent. Virtually complete separation of breeding and non‐breeding sections of the population occurred and non‐breeders gathered at two feeding areas which were also the foci of the winter population.Pairing of first spring females usually occurs in the non‐breeding flocks and bonds are then of long duration.There is an excess of males throughout the year and during the winter, particularly in February, these attempt to pair up by breaking into established pair bonds. Some probably succeed.Flocks of adults in early April were demonstrated to be potential breeders: such flocks appear to provide mutual stimulation. Smaller, socially discrete groups of breeding adults were discovered and named “communes”. These nested together, held adjacent territories and remained in contact throughout the breeding season, even when most pairs had lost nests. They are considered to be the basic social unit of breeding populations, perhaps of all populations.Breeding birds were unevenly distributed such that the density of all nests was one per 230 acres, but the maximum was 6 per acre.Average clutch size of 10·1 and mode of 8 were found from nest records, compared with 8·8 and 9 respectively deduced from broods of ducklings less than three days old. Egg laying began at the end of April and lasted about 81/2 weeks.Incubation spanned some 10 weeks from early May; individual periods averaged 30 days. An automatic recorder showed that one female spent 87% of the available time incubating.Shelduck were found to be single brooded and no evidence of re‐nesting occurred.The brood period started in early June and lasted about 9 weeks. Crêching was considered to result mainly from desertion by parents, but over‐crowding was also a factor. Fledging takes approximately 61/2 weeks.In 1962 and 1963 approximately 54% and 59% respectively of the summer population attempted breeding. Success in getting broods to water (called duckling success) varied from 23·9% to 73·8% in the period 1960 to 1963. This represented a breeding success of 16% to 49·2%. Duckling losses appeared to be heavy.Shelduck generally breed first in their second spring, but some males may not breed until they are almost five years old.
THE FOOD OF SOME LARUS GULLS
Authors: Harris M. P. 
Published: April 2008

SUMMARYThe food of L. argentatus on Skomer and Skokholm Islands (Wales) was studied by the analysis of stomach contents, pellets and direct observation. L. argentatus is mainly a scavenger and exists for the most part on fish‐waste and garbage discarded by man. At Ncwborough Warren argentatus feeds more on arable land and on the shore than do the Skokholm and Skomer birds.Although argentatus frequently eats limpets Patella spp., there is little competition for food between them and Oystercatchers Haematopus ostralegus because the two species eat different sized limpets.A summary of previous studies into the food of argentatus is given. L. marinus is mainly a predator feeding on the young of other gulls, sea‐birds and Rabbits but it also eats carrion, offal and fish‐waste when available and during the winter. The numbers of Manx Shearwaters Procellaria puffinus killed on Skokholm and Skomer are discussed. L. fuscus obtains most of its food on the shore and on arable land. There appears to be little competition, at least in the areas studied, between .fuscus and argentatus for food.
THE BREEDING BIOLOGY OF THE BLACK‐FACED DIOCH QUELEA QUELEA IN NIGERIA
Authors: Ward Peter 
Published: April 2008

SUMMARYA study of the breeding biology of Quelea quelea in Nigeria, and particularly at a large breeding colony near Lake Chad, showed that losses of eggs and young were extremely small. 95% of eggs laid hatched successfully, and 87% give rise to fledglings. Nestling deaths were density‐dependent and apparently due to starvation.The incubation period was 10 days or less. By day, eggs were heated to 34°‐ 37° C. by the sun; at night the females incubated. The nestlings were initially fed mainly on insects, their diet gradually changing to one of seeds—mostly of the grass Echinochloa pyramidalis. The deep body temperatures of young birds were determined. It is suggested that the nestlings left the nest after, on average, 111/2 days to escape intolerable temperature conditions in the nest.Fat reserves were accumulated by nestlings and fledglings, and were utilized when the young became independent. The adults put on fat during the incubation period and lost it during the time spent feeding nestlings.It is concluded that the most common clutch‐size of Q. quelea, which is everywhere three, corresponds to the largest number of young the parents can normally nourish. This conforms to Lack's theory on the significance of clutch‐size, and gives no support to Skutch's opinion that the theory does not apply to tropical birds.