bluuebunny/crossref_metadata_2025_split huggingface dataset:
OBSERVATIONS ON THE ROOK CORVUS FRUGILEGUS IN SOUTHWEST CORNWALL
Authors: COOMBS C. J. F. 
Published: April 2008

SUMMARY

Observations on the breeding behaviour of Rooks were made between 1943 and 1955. The gonads of a series of Rooks from the same area and during the same period were examined (Marshall & Coombs 1957). The autumn sexual resurgence is comparable to early spring in both gonad condition and behaviour.
Display postures are described. A slow wing‐raising component, common to several postures, is very rare and perhaps absent when the testes are refractory. It might have a sexual significance.
Rooks use song posts, but song is not used in the establishment or defence of territory.
Copulation occurs most frequently between birds that are not paired to each other. It is usually interfered with, and in more than 90% of the incidents observed the female was incubating. Resemblances between the incubating position and the female soliciting posture may lead to this.
The territory is a small area round each nest: neighbouring territories may overlap. Rooks who are active in pilfering a neighbour's nest for building material, may establish some territorial dominance over it.
Nest sites are selected by both sexes and in both spring and autumn. Either sex can build a nest. Normally the male does most of the stick structure, and the female more of the cup and lining.
During incubation the female is fed on the nest by the male, and after the young have hatched for as long as he can provide food for her as well as the young. Droppings are removed by both parents, partly as a response to fouling of the nest.
Development of the gonads and of the behaviour of juveniles is described. A few birds reach breeding condition at one year old, the majority a year later. Expectation of life at one year old is probably four years.
Some data are given on the relationship with other Corvidae in the area and with some other species.
FURTHER OBSERVATIONS ON MIGRATION IN SOUTHWEST IBERIA
Authors: Henty C. J. 
Published: April 2008

SummaryDetails are given of autumn migration in southwest Iberia, observed at points from Sagres to Tarifa, 24 August‐23 September 1958.No ‘ rushes ’ of night migrants were encountered and an overall broad front movement probably occurs. Hirundines and raptors passed through daily only at Tarifa.Migration is discussed in relation to local and general weather conditions.
“NONSENSE” ORIENTATION IN MALLARD ANAS PLATYRHYNCHOS AND ITS RELATION TO EXPERIMENTS ON BIRD NAVIGATION
Authors: Matthews G. V. T. 
Published: April 2008

SummaryA strong tendency in non‐migratory Mallard to fly N.W. on release is described. This orientation is shown regardless of distance and direction of release, of season or of length of captivity. It is shown at any time of day by birds of both sexes and of all ages, and is unaffected by the topography of the release site. Head winds of moderate strength impart a wider scatter, otherwise winds have little effect. It appears to be a sun‐compass orientation.The orientation breaks down, probably quite quickly, and is replaced by random wandering. There are no indications of true navigational ability.It is suggested that the orientation may function to keep flocks together and be related to the northward post‐fledging movements of many birds.The existence of such a strong orientation and its presence in another non‐migratory bird, the pigeon, is considered to have caused confusion in experiments on navigation undertaken with the latter. Results obtained with pigeons in N. Carolina and Germany can no longer be considered conclusive. The conflict of their results with those obtained in England is resolved.
THE SONGS OF SOME FAMILIES OF THE PASSERIFORMES. I. INTRODUCTION: THE ANALYSIS OF BIRD SONGS AND THEIR EXPRESSION IN GRAPHIC NOTATION
Authors: Thorpe W. H. , Lade B. I. 
Published: April 2008

SummaryThe sound spectrograph, s an indispensable tool for the fuller objective analysis of animal vocalisation. It is particularly valuable in study of bird song. The sound spectrograms themselves, as produced by the instrument, contain, however, an excess of information which is not always relevant to the comparative study of specific songs. Moreover, the scale and delicate shading of the originals render them needlessly difficult for the field student of bird song to interpret, and needlessly expensive for journals to reproduce. A simplified and graphic notation, consisting of a series of conventional symbols, has been worked out. This, it is believed, largely overcomes these difficulties without the loss of any information essential for the field student.
COMPARATIVE BIOLOGY OF THE WHITE BOOBY AND THE BROWN BOOBY SULA SPP. ATASCENSION
Authors: DORWARD D. F. 
Published: April 2008

SUMMARYThe breeding cycles and related biology of the White Boorby Sula dactylatra and the Brown Booby S. leucogaster at Ascension were investigated between November 1957 and April 1959.In both species there were marked peaks of laying, with intervening periods of very few new clutches. In the White Booby, although only one full season was studied, an annual cycle was deduced; in the Brown Booby (two full seasons) the cycle appeared to be eight‐monthly. The breeding season (laying of eggs to fledging of chicks) was however roughly the same length in both species, namely six to seven months. Individuals of both species for the most part conformed to the breeding seasons of the population as a whole, i.e. if out of phase for some reason, had a longer or shorter “rest” period as necessary to bring them into phase again for the next season. These discoveries indicate that external factors are controlling the times of breeding. The proximate factors are not known; at Ascension there is no appreciable seasonal variation in day‐length or climate, and possible cycles in the surrounding sea could not be investigated.The two species' periodicity was such that, if maintained, every two years they would lay at almost the same time of year, July–August. The possible relation of these observations to a single underlying factor, perhaps annual variation in oceanic conditions with their origin in the seasonal melting of the Antarctic ice and consequent effect on the food cycles, is discussed.Details of incubation, desertion, feeding, care and growth of the chick are given. The regular death of the second chick as a result of asynchronous hatching, and experiments with twins are described. A low breeding‐success, and deaths of chicks from starvation, indicated that both species suffered a shortage of food over an ill‐defined period around August‐September 1958. Regurgitations of food examined throughout the study, and a few observations on feeding, indicated a big overlap in the two species' diets, mainly flying‐fish, but some differences did appear.Details of moult, mainly in the White Booby, are given. Shedding and re‐growth of the juvenile primaries began at about seven months of age, proceeding from the innermost outwards in three spaced concurrent cycles, this remarkable pattern continuing throughout adult life. A period of pause in the primary moult was correlated with the time when most birds had chicks, but some birds were known to be moulting their primaries while breeding. A prolonged moult with a pause during breeding was indicated by examination of some other Ascension species; the relevance of this to the availability of food and breeding seasons in tropical sea‐birds is discussed.
BEHAVIOUR OF BOOBIES SULA SPP.
Authors: Dorward D. F. 
Published: April 2008

SUMMARYSome previously undescribed behaviour patterns, mainly of the White Booby and Brown Booby, were observed in the course of 15 months' general study of the species at Ascension.The advertisement display of the male was similar to a posture described as a “taking‐off” one in the Gannet, but was clearly used by unmated male White Boobies to attract a mate; in the Brown Booby the same display was performed (and sometimes in flight) by males of established pairs. Two postures, both involving a turning‐away of the prominent facial features and therefore comparable to “Head‐flagging” in gulls, were similar in the two species, but again were seen frequently among unmated White Boobies but established pairs of Brown Boobies. One of these was similar to “Bill‐hiding”, a posture seen in attacked chicks. Others among the twelve behaviour patterns described are food‐begging of the chick (apparently similar to “Head‐wagging”, a movement seen during combats between adult White Boobies, but not Brown), and a remarkable sunbathing posture.It is suggested that some of the behavioural differences are related to differences in the two species' nesting habits at Ascension.
BREEDING DENSITY IN THE PEREGRINEFALCO PEREGRINUSAND RAVENCORVUS CORAX
Authors: Ratcliffe D. A. 
Published: April 2008

SUMMARYThe relative stability of breeding density in the Peregrine and Raven in certain inland districts is examined in relation to population limiting factors. Problems of cenus‐making are considered, particularly the use of alternative nesting places. Breeding populations of the Raven have not fallen below 15% of the maxima since 1945. While the Peregrine now shows signs of local decline, it had numeral stability equal to the Raven during the preceding period, and this is the state under consideration.Of possible controlling factors, food supply is unlikely to be directly limiting. For breeding to occur, cliffs suitable in altitude, vertical height, cover and presence of ledges are necessary. Alternative cliffs and ledges are used if available but are not essential to ensure regular occupation of a territory. Availability of suitable cliffs controls nesting density at the lower levels, but does not impose an upper limit.The Golden Eagle is a dominant competitor for nesting cliffs and perhaps for food, and when nesting space is limited Peregrines and Ravens may compete with each other for cliffs. Deliberate persecution can deplete adult populations temporarily and reduce breeding success, especially in the Peregrine, but does not limit breeding density over a period, except in unsuitable terrain. For both species, breeding success and/or migration are sufficient to maintain numbers in the study regions. When breeding success is high, no increase in nesting populations follows. The Raven has non‐breeding surplus populations during the breeding season but this is less certain for the Peregrine.Although direct evidence for its existence as defence of an area is scanty, territorialism is regarded as the factor controlling maximum nesting density by producing a “proximity tolerance limit” between adjacent nesting pairs. It is believed that such territorialism is not itself an ultimate limiting factor but has evolved in relation to food supply so that the numbers of predators are permanently balanced against this factor.
RADAR OBSERVATIONS OF BIRD MIGRATION IN CYPRUS
Authors: Adams D. W. H. 
Published: April 2008

SUMMARYObservations by radar were made of bird migration in Cyprus in October and November 1958 and March to May 1959.Migration was found to occur almost daily, usually beginning three‐quarters of an hour after sunset.The standard direction of migration in October was S. to S.S.E., but in November there were movements both S. to S.S.E. and S.S.W. to S.W.Most spring migrants flew tracks between N.N.E. and N.E., but about 10% flew N.W., including the largest single passage recorded.Some bird‐tracks were seen avoiding high ground and coasting at high altitudes by day, and once by night in bright moonlight.The significance of the results is discussed.
MIGRATION ACROSS THE SOUTHERN NORTH SEA STUDIED BY RADAR PART 5. MOVEMENTS IN AUGUST, WINTER AND SPRING, AND CONCLUSION
Authors: Lack David 
Published: April 2008

SummaryArrivals of gulls S.W. seem almost confined to late July.In August, the main movements are W. by day and night of Lapwings and S.S.E. by night of warblers. Sand Martins migrated at dawn directly from a large roost at 34 m.p.h.In midwinter, migration occurred in at least one direction almost every morning and night. “Hard‐weather movements” west or south are initiated primarily by easterly or northerly winds respectively, and not by cold. The corresponding return movements, which sometimes follow immediately, arc initiated primarily by westerly or southerly winds respectively, but warmth has an influence in February. In midwinter, various species are evidently ready to travel in either the autumn or the spring direction, and wind‐direction is the paramount factor determining which occurs.The big eastward departures in March and April occur mainly with westerly winds and in warm weather, both factors being important, but proportionately more departures occur against strong head or cross‐winds than in autumn. The general weather situation has no direct influence.Starlings migrated directly from their roosts on a few mornings each spring, normally at sunrise but on one occasion some did so much earlier.In late April and May the chief movements are N.N.W. arrivals and onward passages of British summer visitors, N.E. departures of shore‐birds, and N.N.E. departures of small passerines, presumably en route between Iberia and Norway. These movements occur mainly with southerly winds, but sometimes against the wind.“Reversed movements” W. or S.S.E. are much more frequent in spring than has previously been supposed. They occur exclusively with easterly or northerly winds respectively (like the midwinter movements).The frequency of each migratory movement throughout the year is summarized in Table 6.The main findings of the 5‐year study are reviewed under four heads in the Conclusion.
INTER‐SPECIFIC RELATIONS BETWEEN SOME ANDEAN BIRDS
Authors: Moynihan M. 
Published: April 2008

Summary.Four types of partly nectarivorous and partly insectivorous “honey creepers”, Diglossa lafresnayei lafresnayei, D. carbonaria aterrima, D. cyanea cyanea and Conirostrum cinereum fraseri are more or less common near Quito, Ecuador. They compete with one another to a very considerable extent, since their ranges are broadly overlapping, they occur in many of the same habitats, and they feed on many of the same flowers and types of insects in exactly the same places.The relations between these birds are so distinctive and so obviously specialized that they may be considered to form a special social group or “complex”. Some of the reactions between individuals of different species in this complex are quite different from both their intra‐specific reactions and their reactions to other species (not belonging to the complex). This differential responsiveness is shown in three ways.

Individuals of different species of this complex never (or almost never) come close together, due to the fact that they deliberately refrain from approaching one another. They also keep apart from other individuals of their own species (except members of the same family group), but they do this by defending territories against such individuals, not merely by refraining from approaching them. They do not refrain from approaching individuals of any other species.
Individuals of different species of this complex never (or almost never) become openly aggressive toward one another; but they do show such hostility toward most other individuals of their own species and (usually to a lesser extent) individuals of all other species.
Individuals of different species of this complex usually refrain from singing simultaneously. They do not show the same degree of restraint when other individuals of their own species are singing, and they usually ignore the songs of other species.

All the distinctive features of the behaviour of the different species of this complex toward one another seem to be adaptations (or the results of adaptations) to permit them to live in the same areas and habitats, during the same general periods of time, and still remain segregated from one another at any given moment. There is reason to believe that this type of segregation may be more advantageous than inter‐specific fighting.It seems likely that the members of this complex have been in contact with one another for a long time. Some of the morphological and behaviourial characters of lafresnayei, cyanea, and fraseri seem to be adaptations to the presence of aterrima. Theoretical considerations would suggest that there will be strong selection pressure against both further divergence and convergence of these forms as long as it continues to be advantageous for them to maintain the same interspecific relations with one another.
THE PELAGIC DISTRIBUTION OF THE SOOTY SHEARWATERPROCELLARIA GRISEA
Authors: Phillips J. H. 
Published: April 2008

Summary.The breeding distribution of the Sooty Shearwater and the dates of its breeding season are briefly reviewed.Records from the Southern Ocean are summarised. It is concluded that they are accounted for by non‐breeding birds feeding off the ice‐edge in the Australian sector of the Antarctic during the latter part of the breeding season.The great majority of Sooty Shearwaters spend the southern winter in the Pacific Ocean. Birds from the New Zealand colonies are probably mostly found on the feeding grounds off Japan: some may make a “circular” migration around the Pacific. Birds from the Cape Horn colonies spend the southern winter in the rich areas off the western coast of North America.Some Sooty Shearwaters spend the southern winter off the South African coasts. A number of non‐breeding birds remain there throughout the summer.The Sooty Shearwaters “wintering” in the North Atlantic are probably numbered in tens of thousands only. The distribution of records is reviewed month by month and the records from Atlantic transects are summarised. The migrations in the North Atlantic are discussed in relation to prevailing meteorological and oceanographic conditions, and food supply. It is concluded that most Sooty Shearwaters in the North Atlantic make a “circular” migration, crossing the North Atlantic from west to east in June and July, and re‐crossing about September further south in the northeast trades.
THE BIOLOGY OF THE WIDEAWAKE OR SOOTY TERN STERNA FUSCATA ON ASCENSION ISLAND
Authors: Ashmole N. P. 
Published: April 2008

SUMMARYWideawakes Sterna fuscata were studied on Ascension between October 1957 and April 1959. As shown by Chapin, breeding in this species occurs every nine and a half months on Ascension, and two complete breeding periods were observed. Some of the birds are close to the island even in the non‐breeding period, and many settle on the breeding ground at night during the two months before breeding begins, although they suffer serious predation from cats at this time.The Wideawakes breed in dense colonies, usually on rocky ground. The single egg is incubated by the parents alternately, in shifts which on Ascension last up to six days, probably indicating that food cannot be found quickly, close to the island. The fledging period is long, but the rate of development flexible: the young can survive long periods on very little food, but grow relatively fast when given more food. In spite of this adaptation many young died of starvation in the second breeding period observed, while those which survived took longer to fledge than the chicks raised in the previous breeding period. The chicks also suffered severe predation, from frigate birds when very young and from cats when older. Together, these factors resulted in strikingly low breeding success.Individual Wideawakes on Ascension breed at intervals of 41–51 weeks, and between successive breeding periods undergo a complete moult: they finish one moult before returning to breed, but may start the next moult before their chicks are full‐grown. The length of the interval (9 months) between the start of laying in successive breeding periods appears to be determined by the time required for breeding activities, a complete moult, and an assembly and courtship period during which social stimulation is probably important.In an appendix are listed the recorded times of breeding of Wideawakes in all parts of their range: previously undiscerned six‐monthly or non‐seasonal breeding is documented for several localities.
THE REGULATION OF NUMBERS OF TROPICAL OCEANIC BIRDS
Authors: Ashmole N. P. 
Published: April 2008

SUMMARYThe ways in which the numbers of tropical sea‐birds might be limited are considered; it is argued that food is the only factor likely to be generally effective in limiting numbers, but it seems improbable that food shortage could exert a density‐dependent control of the mortality of the birds outside the breeding season.Wynne‐Edwards' hypothesis that colonies of sea‐birds are able to keep their own numbers below the level at which food shortage would become acute, primarily by exerting control on the output of young, is rejected as unproven and improbable.It is suggested that colonies of tropical oceanic birds deplete the food in the waters round them, and that as the populations increase competition for food becomes more intense, and relatively fewer adults succeed in raising chicks. This would provide a density‐dependent control of the output of young and could regulate the numbers of the birds.The peculiarities of long‐lived sea‐birds (e.g. clutches of one, long fledging periods, deferred maturity) which Wynne‐Edwards suggests are adaptations evolved in order to lower the reproductive rate until it balances the mortality, apparently could not be evolved as such; they are more probably adaptations enabling the birds sometimes to raise single chicks in spite of competition for food that makes it impossible to raise more than one. It is considered that variation in the age of first breeding provides an important supplement to variation in reproductive success in regulating the numbers of long‐lived tropical sea‐birds.The possible applications of this hypothesis to sea‐birds breeding in higher latitudes are briefly considered, as are its implications in relation to conservation and exploitation of populations of sea‐birds.
THE LAYING DATES OF SOME ST. HELENAN SEA‐BIRDS, 1958‐59
Authors: Stonehouse Bernard 
Published: April 2008

SUMMARYLaying dates of six species of sea‐birds on St. Helena were determined in the spring and summer of 1958–59 by members of the B.O.U. Centenary Expedition on two visits from Ascension Island. Laying dates of the same species on Ascension Island are compared. Only two species showed close seasonal agreement between the two islands.