bluuebunny/crossref_metadata_2025_split huggingface dataset:
BODY WEIGHTS IN LAYSAN ALBATROSSES DIOMEDEA IMMUTABILIS
Authors: Fisher Harvey I. 
Published: April 2008

SummaryMale Laysan Albatrosses are heavier (3300 gm.) than females (3000 gm.) upon arrival on Midway. This difference between the sexes persists except at egg‐laying and during certain periods of incubation.Weights of males and females are essentially the same at egg‐laying, perhaps because of the presence of the 300 gm. egg in the female, but mostly because the males have lost weight in the pre‐egg phase.Losses in weight during the long, continuous incubation spans are about 18–25% of the body weight. Males show a net loss of about 10% during the entire incubation period; there is no statistically significant change in the weights of the females.Weights of both sexes decline in parallel from the end of incubation to mid‐May. Thereafter, they increase as attentiveness to the young is less and the parents have more time to forage at sea. Nevertheless, the body weights of both sexes at the end of the breeding season (July) are down 10–45%.Decreased body weights of breeding birds cannot be attributed solely to the rigours of parental care; former breeders and juveniles not yet of breeding age show a similar decline in weight.It is suggested that the normal pattern of yearly breeding by adult Laysan Albatrosses may be broken by failure to add weight (fat) before the breeding season. Former breeders consistently weigh 15–20% less than current breeders.Nestlings normally show a gradual increase in body weight from hatching in late January until mid‐May, at which time they may be significantly heavier than either parent.As a result of the increased energy requirements of locomotion and wing exercise and decreased food supplied by parents, nestlings lose about 30% of the May weight before they finally go to sea in JufyA possible “mutation” for small body weight is discussed.
COMMUNAL ROOSTING BEHAVIOUR OF THE AUSTRALASIAN HARRIER CIRCUS APPROXIMANS IN NEW ZEALAND
Authors: Gurr L. 
Published: April 2008

SummaryThe Australasian Harrier Circus upproximans habitually roosts communally in New Zealand but not in Australia. As many as 100 birds can occupy a roost in a small area of swamp. They start to assemble about one hour before dark and communal aerial displays in the vicinity of the roost are an integral part of the roosting behaviour. Roosts may be occupied all the year round, non‐breeding birds continuing to roost communally throughout the summer. In New Zealand the habit is neither connected with migration nor is it an anti‐predator device. It is considered that the abundance of food caused by the spread of introduced mammals and the large increase of habitat created by European settlement has built the harrier population up to such a size that the number required to elicit the response of communal roosting occurs at all times of year in most districts. Numbers within individual roosts fluctuate throughout the year and it is suggested that communal displays before roosting may provide the necessary feed‐back for the initiation of population adjustments.
THE BIRDS OF RODRIGUEZ, INDIAN OCEAN
Authors: Bourne W. R. P. 
Published: April 2008

SummaryThe present paper reviews several little‐known 18th century accounts of the sea‐bird fauna of Rodriguez, Indian Ocean. After a brief description of the history of the islands, early information on the sea‐bird colonies is summarized together with a reasoned interpretation of the species involved. Several species no longer known to breed bred in the 18th century. Subfossil petrel bones also indicate the existence of several species now absent, including the Mascarene PetrelPterodroma aterrima. These are described and figured. The scant evidence on sea‐bird breeding seasons suggests the existence of some out‐of‐season and staggered breeding. Finally, a few recent records of land‐birds are listed with some comment on the oriental origin and affinities of the species, and the need for measures to conserve the existing avifauna is stressed.
AUDITORY EXPERIENCE AND SONG DEVELOPMENT IN THE CHAFFINCH FRINGILLA COELEBS
Authors: Nottebohm Fernando 
Published: April 2008

SummaryThe present paper describes the results of experiments designed to evaluate the importance of auditory‐motor experience in the development of song in the Chaffinch. For this purpose a number of Chaffinches collected as nestlings or adults were deafened by extirpating the cochlea at different ages. Recordings of their song made subsequently provide the material on which the paper is based.Since the results of the experiments can only be interpreted in the light of knowledge of normal song development, the latter is described from the observation of previous workers and from some new material.Of the 20 males deafened, only three came into full song of their own accord; song was induced in the rest by the administration of testosterone phenylacetate or testosterone propionate. Songs of abnormal length were common among first‐year males though males deafened when two or more years old produced song of the normal length. The song of male Chaffinches deafened as adults, that is after they had produced full song for one or more breeding seasons, was infistinguishable from that produced by intact adult males. They even went through a “plastic” song stage in which some “intermediate” themes occurred. A first‐year male deafened when it had almost stabilized its song produced song that gradually deviated more and more from normal song. This indicates that the bird had not yet laid down a long‐term memory of its song independent of auditory feedback.First‐year male Chaffinches deafened during early spring, mid‐winter and late sumer, respectively, show that the more they were deprived of the normal period of auditory‐motor experience, the simpler was the song they produced in their first spring. Thus, at the time of deafening they had acquired a particular auditory‐motor experience, and it is the type of element established up to that time that is incorporated into full song.Male chaffinches brought into the laboratory as nestlings and deafened when three months old produced a virtually sfyctureless song, in which the only recognizable element was a sound reminiscent of the juvenile “chirrup”. The subsong and other calls of these birds were also highly abnormal. Song development in the Chaffinch clearly starts before song as such has made its appearance.The available evidence suggests that the kind of song a male Chaffinch produces depends directly on its auditory‐motor experience before deafening. There is no indication that deafening achieves its effects on the resultant song by interfering with the hormonal substrate.Relatively stable song end patterns develop in the absence of auditory feedback, so their occurrence does not necessitate the postulation of templates or preconceived patterns. Song development differs markedly from species to species.
STORM‐PETRELS OCEANODROMA SPP. IN THE INDIAN OCEAN
Authors: Bailey R. S. , Pocklington R. , Wrllrs P. R. 
Published: April 2008

SUMMARYIn the course of the International Indian Ocean Expedition two storm‐petrels, thought to be Oceanodroma matsudairae and O. monorhis, were encountered in the western Indian Ocean in some numbers. Two specimens of each species were collected, monorhis in the Arabian Sea, matsudairae off N.W. Australia. O. matsudairae, which had not been recorded before from these waters, appeafed to be concentrated within 5° of the equator and the birds probably belonged to the spring‐breeding population of Volcano Island. O. monorhis was found mostly in the Arabian Sea. Bulweria bulwerii, for which there was but one certain Indian Ocean record, was also encountered several times.
THE IBIS
Authors: Ash J. S. 
Published: April 2008

SummarySome aspects of the weights of over 5,500 birds of 79 species, mostly migrants, captured in spring at an oasis on the northern edge of the Sahara, are discussed. Mean weights for five species were 26–44% below those of fat birds (those containing at least 30% lipid) weighed about the same time on the south side of the desert. Weights of fresh arrivals in Britain are higher than those in North Africa, but the differences are not great, suggesting that these have also made a long journey across Europe. Peak arrival times of day‐migrants differed from those of night‐migrants and the weights of some species varied with the time of day. There was no great advantage to migrants in remaining at the oasis; there were few weight changes greater than those normally occurring within an individual's daily range. Several species lost weight steadily during a cold spell, and many died. Male Swallows are heavier and larger than females, and in both sexes weight increases with wing‐length.
OBSERVATIONS ON THE LAVA GULL LARUS FVLIGINOSUS
Authors: Snow B. K. , Snow D. W. 
Published: April 2008

SummaryLava Gulls Larus fuliginosus live as scavengers and unspecialized predators along the shores of the Galapagos Islands. Although they concentrate locally at places where refuse is available, their breeding density is low: eight breeding pairs were found along a stretch of 35 miles of the coast of Indefatigable Island. The total (world) population is likely to be less than 300–400 breeding pairs.Their low breeding density and small total population is attributed to the fact that they are confined to linear feeding grounds of limited extent, which provide a sparse food supply for much of the year.Lava Gulls nest solitarily, usually in sheltered places near coastal lagoons; all the nests found were at least two miles from any other known site. The clutch consists of two eggs, incubation (one case) lasts 32–33 days, and the fledging period is about 60 days.Breeding takes place throughout the year, with no apparent peak. Individual cycles of 9–12 months have been recorded.Observations are given on behaviour and displays, and on the sequence of plumage change and moult in the first two years of life.
POLYMORPHISM IN RINGED PLOVERS
Authors: Smith N. G. 
Published: April 2008

Summary.The rather similar ringed plovers Charadrius hiaticula and C. semipalmatus represent essentially allopatric, circumpolar populations which overlap in the breeding season only in a narrow zone in the eastern Canadian Arctic.In eight fiords on eastern Baffin Island, semipalmatus was the more numerous by a factor of almost three. Both plovers occurred together, although not in equal numbers, in the same wide range of habitats.Pair formation in both plovers apparently took place at the same time, but for more than half of the individuals, not in the same geographic area. The majority of the hiaticula individuals arrived after most semipalmatut, and the late arriving hiaticula appeared to be paired upon reaching Baffin Island. There was an overlap in their arrival times of about five days. Mixed hiaticula‐semipalmatus courtship groups occurred during this period. Pair forming activities of hiaticula and semipalmatus appeared similar but were not studied closely.Analysis of the non‐overlapping territories of two populations suggested that the plovers did discriminate one type from the other for there was a tendency for unlike pairs to nest side by side. The significance of this odd pattern is not known.Analysis of the mensural and plumage characteristics of adult plovers from the overlap zone seemed to indicate that gene flow between the two was absent and that they were behaving as distinct species. However, mixed pairs occurred in five out of eight fiords. Considering the populations of all fiords, the number of mixed pairs found (20) was significantly greater than theoretical expectation, which allowed for an occasional mixed mating since a choice of mate was not always possible.All mixed matings produced mixed broods. The young were either hiaticula or semipalmatus. No intermediates occurred. Moreover, 10 pairs in which both birds were pheno‐typically “semipalmatus” produced both semipalmatus and hiaticula‐type chicks. No intermediates were detected. Egg and chick mortality probably prevented the detection of more such cases. All hiaticula x hiaticula matings produced only hiaticula‐type chicks. The inheritance data indicated that hiaticula and semipalmatus are morphs of a single polymorphic species.If a switch gene is operating, it may have originally controlled only toe‐webbing, and the other differences may have accumulated as the result of geographic isolation. That differences in plumage pattern and body size are greatest where separation was probably longest supports this hypothesis.One possible model considered semipalmatus‐type individuals to be either SS or Ss and hiaticula‐types to be ss. Accordingly, all semipalmatus‐types involved in mixed matings with hiaticula‐ types would have been Ss individuals because all such matings produced chicks of both types.Circumstantial evidence suggested that during the last 80 years, the relative number of the two types in the overlap area has shifted in favour of the semipalmatus‐ type. This might have been the result of selective factors intrinsic to the polymorphism.
PREY TAKEN BY TAWNY OWLS DURING THE BREEDING SEASON
Authors: Southern H. N. 
Published: April 2008

Summary.The diet of Tawny Owls during the breeding seasons 1949‐52 in Wytham Woods, near Oxford, was determined (a) from analysis of pellets collected, (b) from observation at night, by the use of a red floodlight, of prey brought to the nest and (c) from records of prey left in the nest made during daily visits to weigh the young.Analysis of pellets showed an increase in the proportion of moles and beetles (mainly cockchafen) in the diet after the first week of May (the time when, on average, the young owls are about half grown) and a decrease in the proportion of mice and voles.These changes were confirmed in a more emphatic way from observations of food being brought to the nest and from records of prey left in the nest.This greater emphasis suggests that tho food brought to the young may differ from that which the adults eat themselves.The fact that no moles were observed being brought to nests at night, wherean many were recorded as surplus prey in the nest, showed that diurnal hunting is regular during the breeding reaaon.A true assessment of prey taken by Tawny Owls during the breeding season should be based both on analyeis of pellets cast by the adults and on records of food brought to the nest throughout 24 hours. Such records could best be obtained with an automatic camera and flash and a design of nest‐box which is described.
NEST PARASITISM AND DISPLAY OF CHESTNUT SPARROWS IN A COLONY OF GREY‐CAPPED SOCIAL WEAVERS
Authors: Payne Robert B. 
Published: April 2008

Summary.Chestnut Sparrows Passer eminibey near Magadi, Kenya, built no nests of their own but usurped nests newly built by Grey‐capped Social Weavers Pseudonigrita arnaudi. The sparrows laid eggs and raised their own young in the appropriated nests. The sparrows were synchronized in their breeding with the social weavers but appeared to have a slightly later peak of breeding. Breeding of the sparrows may be stimulated by the sight of breeding activity of the social weavers. Breeding occurred in May and June at the end of a rainy season.Male Chestnut Sparrows display at the nests with the wings raised. The display is given for several hours each day. Examination of nests built by the social weavers is an element of courtship display by the male sparrow.In the subfamily Passerinae there is a greater difference in the form of the courtship display between the Chestnut Sparrow and other species of Passer than between nest‐building species of Passer and other genera. The display of Chestnut Sparrows is derived from the nest‐advertisement display of nest‐building Passer. Its exaggerated form may be an adaptation related to pair formation and intrapair sexual stimulation in the absence of male nest‐building behaviour.
OBSERVATIONAL LEARNING IN THREE SPECIES OF BIRDS
Authors: Alcock John 
Published: April 2008

Summary.White‐throated Sparrows Zonotrickia albicollis, Fork‐tailed Flycatchers Muscivora tyrannus and Black‐capped Chickadees Porta atricapillus were placed in experimental situations where they could watch a trained companion uncover a hidden mealworm. After a period of watching its companion find the concealed mealworm, the observer bird was isolated visually from the other bird. While in isolation the observer birds approached, touched and pecked at a hidden food tray significantly more often than control birds which had not had an opportunity to observe a trained companion. However, the experimental birds failed to learn from observation alone how to uncover the concealed mealworm. But if rewarded in the presence of the companion bird (by taking a mealworm from it or by uncovering a mealworm as a result of local enhancement), then the observer bird frequently did come to find the prey in isolation. It is suggested that the interaction between observational learning and a bird's reinforced socially facilitated experience could assist in the development and expansion of a bird's behavioural repertoire.
BIRD MIGRATION OVER THE MALTESE ISLANDS
Authors: Lucca C. De 
Published: April 2008

Summary.The present paper is based on data obtained during several years' observations and three recent surveys. Little has previously been published on migration through the Maltese Islands.The geographical, vegetational and climatic factors of the islands are discussed in so far as they affect the migrants.Visible migration is seen with anticyclonic weather and westerly winds. Birds are found grounded after night migration in cyclonic weather with southwesterly or easterly winds, much larger numbers and variety being seen with the latter. When there is a deterioration in the weather during the night, a large influx of birds is seen on the following morning, and in addition large flocks of migrating Turtle Doves are seen.Several trans‐Saharan migrants may pass in smaller numbers during autumn than spring, but the difference may be more apparent than real because in early autumn the birds may depart after only a very short stay, and a few conspicuous species are absent or scarce. By contrast several species which winter north of the Sahara pass only or in much larger numbers during autumn, and these more than make up for those which are absent or rare.There is no evidence from bird ringing that in spring Malta regularly gets birds from Tunisia, at any rate from that part covered by the ringing stations (Cap Bon, Enfidaville, Gabes). The migrants which pass through Malta probably originate from an area in North Africa around Tripoli and some way westwards of it. During autumn the bulk of recoveries is from eastern European countries with a smaller percentage from northern and central Europe.Several species or groups of species are dealt with individually.In the discussion stress is laid on the very close relationship between migration and weather, especially the wind component. The comparatively small numbers of birds seen at Malta probably form part of a larger movement travelling on a broad front. It is argued that the large “falls” of migrants in bad weather result from drift acting on a mass passing mainly to one side or the other of the islands. Since much larger densities are seen with easterly than with westerly winds, it follows, if the hypothesis of drift be correct, that the numbers of birds travelling to the east of Malta are larger than those to the west of it. Moreover, since day migrants are seen with westerly winds and the bulk of night migrants with easterly ones, it is inferred that day migrants normally pass to the west, and the bulk of night migrants to the east, of the Maltese Islands. A parallel is drawn between the autumn migration and the performance of racing pigeons which are flown from the north and NE at this season.
THE WINTER FEEDING ECOLOGY OF THE REDSHANK TRINGA TOTANUS
Authors: Goss‐Custard J. D. 
Published: April 2008

Summary.The aim of the work was to find out how the Redshank which over‐winter on the Ythan estuary, Aberdeenshire, adapt their feeding activities to the short daylength in winter. To achieve this, the feeding behaviour and daily routine in winter were compared with those in autumn and spring. Corophium volutator was the main prey on the estuary during the day. However, the temperature of the mud greatly affected the diet in the two areas where the feeding behaviour was studied in detail. At temperatures above 6°C, most of the biomass ingested consisted of Corophium. However, in one study area in one winter, Macoma balthica was taken more frequently at lower than at high temperatures. In the other area, Nereis diversicolor was taken more frequently at low than at high temperatures. These changes in diet appeared related to changes in the behaviour of the prey affecting their availability and not due to the birds changing their preference at low temperatures. The ingestion rate was not affected by the change in diet in the first area but decreased at low temperatures in the second. The sizes of Macoma and Nereis taken by the birds did not vary seasonally. The sizes of Corophium taken decreased in winter as a result of a reduction in the size of those present in the substrate. It was concluded that there was no evidence of Redshank increasing their ingestion rate in winter to compensate for the short daylength.The proportion of the time spent feeding on the estuary in daylight was greater in winter than in spring. Redshank continued feeding at high water in the surrounding fields and on the estuary at night during the winter but not in either autumn or spring. During the winter they obtained less than 50% of their daily food requirements from the estuary in daylight, mainly because of the short daylength. Consequently, they had to collect the balance at night and at high water.Seasonal changes in the numbers of Redshank were recorded. After an autumn decrease in numbers, no decrease in numbers could be detected during the winter. These findings are discussed in relation to the possible difficulties for Redshank in collecting their daily food requirements during the winter. The impact of the birds on their main estuarine prey Corophium is also discussed.