bluuebunny/crossref_metadata_2025_split huggingface dataset:
A FIELD STUDY OF THE BEARDED BELLBIRD IN TRINIDAD
Authors: Snow Barbara K. 
Published: April 2008

SummaryThe Bearded Bellbird Procnias averano, a medium‐sized sexually dimorphic cotingid, was studied for three years in the Northern Range of Trinidad.Its preferred habitat is primary forest at altitudes of 500–1,000 feet and with a rainfall near 100 inches. It is entirely frugivorous, taking mostly drupes. The seeds of the fruits eaten are regurgitated and nearly 2,000 were collected from below the male's calling perch and below nests. Most were from the families Lauraceae and Burseraceae, whose fruits have particularly nutritious pericarps.Adult males own a calling territory from which they call throughout most of the day, and throughout the year except for the period of moult. In each territory there are special saplings where display and mating take place.Only males call; the females are voiceless. The call is loud and far‐reaching. In Trinidad P. averano has only two calls, the Venezuelan birds have a third more musical call which appears to have been lost by the Trinidad bellbird during the past 60 years.Both males and females visit the adult male in his calling territory. Here he performs a ritualized display to the visitor, which shows off his black and white plumage, the beard of wattles, and also a bare patch on the thigh. The visit of the female may culminate in mating. All aggressive behaviour observed was between males disputing over calling territories.The female builds the nest, incubates, and rears the chick on her own. The very inconspicious nest is built of twigs that readily interlock. Nearly all the twigs are from two species of tree, and it is suggested that the specialized nest‐material may be essential, as the female bellbird builds only with the breast and feet. The clutch consists of a single egg. The incubation and fledging periods are both long, 23 and 33 days respectively. The female's visits to the chick are infrequent, brief, silent and inconspicuous. Many details of breeding behaviour indicate that the inconspicuousness of the nest is of paramount importance.The nestling is fed on fruit which the female regurgitates. The main breeding season is from April to July with a minor one in October and November. It takes two and a half years for the male to attain fully adult plumage, and at least two years to achieve a completely adult call.The relationship between type of nest, clutch‐size, feeding habits and sexual bonds in tropical forest birds is discussed. The bellbird is an extreme example of a species in which the need for a very inconspicuous nest and a diet of fruit have combined to promote polygamy, with the emancipation of the male from the nest, and to reduce clutch‐size to a minimum.The bellbird's structural adaptations to its method of feeding in flight are discussed and a comparison is made with the birds of paradise. The male's adaptations for its primary function of self‐advertising are compared with the parallel adaptations evolved in the related Pipridae.
SEA‐BIRD BREEDING SEASONS ON CHRISTMAS ISLAND, PACIFIC OCEAN*
Authors: Schreiber Ralph W. , Ashmole N. Philip 
Published: April 2008

SummaryChristmas Island, at 2° N, 157° W in the Central Pacific Ocean, supports 18 breeding species of sea‐birds. Data on the breeding seasons collected by the authors and other visitors to the island are analyzed in individual species accounts. Population estimates are given, the distribution of each species on the island is outlined, and for some species information on the sexual and moult cycles of marked individuals is presented. The Discussion concerns the ultimate and proximate factors controlling breeding seasons and the role of social factors in maintaining breeding synchrony in sea‐birds, the diversity of the breeding regimes exhibited on Christmas Island (summary and analysis in Fig. 2 and Table 5), and comparison of these regimes with those found in the birds of Ascension Island and the Galapagos Archipelago.
MOULT IN THE SHAG PHALACROCORAX ARISTOTELIS, AND THE ONTOGENY OF THE “STAFFELMAUSER”
Authors: Potts G. R. 
Published: April 2008

SUMMARYThere are three main types of plumage in the Shag, the juvenal which is brown, the post‐juvenal which is dark brown and the nuptial which is black‐green. The replacement of these plumages and the ontogeny of the Staffelmauser was studied in a sample of 566 Shags mainly from northeast England. The replacement of the juvenal primaries starts at the age of eight months with the loss of the innermost primary and continues outwards at a rate of about one primary per 17 days. Another cycle starts when the first reaches the 8th primary but both cycles soon pause for the winter. Successive cycles are established annually in August or September in this way, so that cycles which take longer than one year to complete result eventually in a Staffelmauser in which each feather is replaced once annually. Most individual Shags in a breeding population will retain feathers from two or three cycles, but a large sample of breeding adults of the same age will retain the feathers of four cycles.The winter pause is considered an adaptation to the increased probability of adverse conditions at this time. The system described for the ontogeny of the Staffelmauser is applicable to those other sea‐birds which have been studied in detail, and is probably advantageous since it combines slow moult during the difficult early years with a highly efficient moult during the breeding years, especially where moult and breeding occur together.
HUNTING METHODS AND CHOICE OF PREY OF GYRFALCONS FALCO RUSTICOLUS AT MVTN IN NORTHEAST ICELAND
Authors: Bengtson Sven‐Axel 
Published: April 2008

SUMMARYGyrfalcons breeding near Myvatn in northeast Iceland were studied from 1960 until 1970. Hunting methods and successful attacks are described. The Gyrfalcon usually hunts low over the ground and tries to surprise and flush its victim and then stoop upon it. If this fails, it may pursue.The choice of prey was studied by observations from mid‐May to September of Gyrfalcons carrying prey, and by examining food‐remains at eyries. Ducks and Ptarmigan comprised about 49% and 41 % respectively by number of individuals, and 62% and 35 % by estimated fresh weight. One pair utilised some 88 kg of food to raise foui young.The proportion of Ptarmigan in the diet increased during the study, reflecting the increase of the Ptarmigan population and suggesting that Ptarmigan are the preferred prey since waterfowl were abundant all the time.
THE SOCIAL ORGANISATION OF BEE‐EATERS (MEROPIDAE) AND CO‐OPERATIVE BREEDING IN HOT‐CLIMATE BIRDS
Authors: Fry C. H. 
Published: April 2008

SummaryIn the colony‐nesting bee‐eater Merops bulocki of the northern savannas of Africa males preponderate in the proportion 1 ‐5 to 1 female, initial breeding occurs at varying ages, and adults of both sexes and all age classes, particularly one‐year‐old males, assist breeding pairs with nest excavation, incubation, and provisioning the pulli and fledglings. Up to three helpers can occur at one nest, and they may be siblings of a previous year's brood. Pair‐bonds are for life, and bonds formed between the breeding pair and their helpers may endure until next season. Some evidence suggests that other gregarious open‐country bee‐eater species are similar in these respects but that forest and solitary‐breeding savanna species have the sex ratio at parity and do not breed co‐operatively. Breeding dispersion of savanna species is related to specific size, the largest (which forage most widely) nesting in the densest aggregates.Other instances of birds with comparable social organisations are briefly reviewed. The 80 species involved comprise broad systematic and ecological spectra and about 60 of them inhabit hot climates in America, Africa and Australia. It is suggested that co‐operative breeding provides a reserve of experienced individuals whose recruitment to breeding permits (1) fine control of stable populations in non‐seasonal habitats (tropical forest) within the capacity of the food resources; (2) crude adjustment of fluctuating populations in habitats with unpredictable rainfall (Australia), enabling them rapidly to recuperate from depression and to achieve the highest population level the improved food resources can sustain; and (3) regulation of populations in intermediate habitats (tropical savannas) by either means according to the dictates of immediate ecological circumstances.
MORPHOLOGY OF THE TONGUE APPARATUS OF C1R1DOPS ANNA (DREPANIDIDAE)
Authors: Bock Walter J. 
Published: April 2008

Summary Ciridops possesses a tubular tongue with a fringed tip and lateral sides. Closure of the tube is by overlap of the lateral fringes.The tongue skeleton possesses an elongated basihyale, parallel paraglossalia with broad, rounded posterior processes and a slight concavity on the dorsolateral surface of the ceratobranchiale.All the tongue muscles could be described, although some had been damaged. The M. hypoglossus anterior is absent. The M. ceratoglossus and the M. hypoglossus obliquus are large, the latter muscle inserts completely on the basihyale. A newly discovered muscle, the M. thyreohyoideus superior, is described.The glottal muscles are described, and their actions in opening and closing the glottis are outlined.Comparison of Ciridops (Drepanidinae) and Loxops (Psittirostrinae) suggests that the Drepanididae are monophyletic. The closest resemblance in morphology of the tongue apparatus is with the cardueline finches, not with the “coerebids”.
THE BREEDING OF URBAN WOODPIGEONS
Authors: Cramp Stanley 
Published: April 2008

SummaryEgg‐laying in Woodpigeons in central London lasts from March until September in normal years, with peak production in April and May, contrasting markedly with some rural areas in England where few clutches are completed before May and the peak months are July and August. Both appear to be determined by food supplies; London birds feed mainly on bread, supplemented by vegetable foods, which is in ample supply. so that they require much less time for feeding than rural birds in winter and early spring. They are thus able to breed over the whole period for which they are apparently physiologically capable. Breeding success in central London is almost double that in Cambridgeshire and nearly 50% above that in other rural areas, due to markedly lower predation, especially at the egg stage. The factors governing the breeding seasons of different populations of Woodpigeons are discussed.
SUMMER DISTRIBUTION OF PELAGIC BIRDS OFF THE COAST OF ARGENTINA
Authors: Cooke Fred , Mills Eric L. 
Published: April 2008

SummaryEighteen species of sea–birds were observed from CSS ‘Hudson’ in the South Atlantic between the Rio de la Plata and Tierra del Fuego in late January and late February 1970. Major feeding areas were noted off Mar del Plata, the Valdes Peninsula and Tierra del Fuego, Argentina, the first two in rich modified or unmodified water of the subantarctic Falkland Current, associated with upwelling. The southernmost area had most birds, the northernmost fewest. A temperate–latitude assemblage including Yellow–nosed Albatross and Cory's Shearwater occurred off Mar del Plata in warmed water of subantarctic (Falkland Current) origin. South of 39°S these two species were replaced by Black–browed Albatross and Great Shearwater in cold offshore water of the Falkland Current. Off the Valdes Peninsula Black–browed Albatross, Great and Sooty Shearwaters, White–chinned Petrels and family groups of Magellanic Penguins occurred near the edge of highly–productive water of the Falkland Current. The largest feeding area, east of Tierra del Fuego, had Magellanic and Rockhopper Penguins, Great Shearwaters, King Cormorants, South American Terns and jaegers, but no oceanographic information is available. At 50°S prions and diving petrels appeared for the first time, marking a possible oceanographic discontinuity or proximity to colonies on the Falkland Islands. Several common species of the South Atlantic were not seen on the transect including Cape Pigeon, Southern Fulmar, Soft–plumaged Petrel, Schlegel's Petrel and Pediunker. Kelp Gull, South American Tern, Manx Shearwater and jaegers were rare or absent far from land. New southern limits for the western South Atlantic Ocean were established for Cory's and Manx Shearwaters, and the Great Shearwater was observed for the first time in Chilean waters.
THE FLIGHT OF ALBATROSSES (A COMPUTER SIMULATION)
Authors: Wood C. J. 
Published: April 2008

Summary.The equations of motion for gliding flight in a wind gradient have been used to study the way in which the albatross can gain height in non‐powered flight against a purely horizontal wind. It is argued that a type of potential and kinetic energy parameter is convenient for the assessment of climbing performance if the kinetic energy term involves the airspeed rather than the absolute velocity. The gradient with height of this parameter shows a maximum value at a particular climb angle for each speed and wind gradient.Two types of complete flight cycle have been investigated in a logarithmic wind velocity profile having a speed of 15 m/sec at a height of 10 m. The emphasis in the study has been on the possibilities of making progress against the wind. Progress in any other directions is very much easier to achieve.The first cycle is simple and unidirectional with an upwind dive. Although this leads to a fairly rapid progress against the wind it is shown to be impossible without some power input.By contrast, the more usual flight cycle which involves a dive in the downwind direction is completed very easily without loss of flying speed. In fact, by diving steeply, sufficient excess airspeed can be gained to permit a very long final upwind glide at low level. This repasses the starting position and thus gives a slow but definite nett progress against the wind.
ECOLOGICAL SEPARATION BETWEEN WHITE AND PINK‐BACKED PELICANS IN THE RUWENZOFU NATIONAL PARK, UGANDA
Authors: Din N. A. , Eltringham S. R. 
Published: April 2008

SummaryThe number and distribution of the White Pelican Pelecanus onocrotalus roseus and the Pink‐backed Pelican P. rufescens were studied in the Ruwenzori National Park, Uganda, by means of aerial surveys carried out at approximately weekly intervals between May 1968 and December 1969.The White Pelican is migratory and was present in the Park at highest numbers in August 1968 and May 1969 when 2510 and 3927 respectively were recorded. It does not breed within the Park. The Pink‐backed Pelican is resident, with a population averaging about 1350 birds.Pelicans are distributed in discrete flocks on loafing grounds. Flocks of the White Pelican tend to be bigger than those of the Pink‐backed. Forty‐three loafing grounds were recognized in the Park, and it is shown that there is no difference between the species in the frequentation of these grounds. The areas favoured by both species are characterized by flat, open stretches close to water; steep slopes and heavily vegetated shore‐lines are avoided.The feeding behaviour was studied by direct observation and through cine‐photography. Only the White Pelican feeds communally in coordinated groups; this species also often feeds singly. The feeding sequence of both species is described, and is divided into four phases:searching, trapping, catching and swallowing. The searching phase lasts about six times longer in the Pink‐backed Pelican than in the White. The White Pelican feeds further from the shore than does the Pink‐backed. There is little difference between the species in the daily feeding pattern. Feeding takes place throughout the day but mostly from dawn to about 10.00 hrs and from 17.00 hrs until dusk. The rest of the day is spent mainly in preening, resting or bathing.The food of pelicans is exclusively fish. The White Pelican takes mainly large Tilupia, and Haplochromis and fish fry to a lesser extent. The Pink‐backed Pelican feeds largely on fish fry, but Tilapia and Haplochromis are frequently taken and by weight are more important than the fry. However, the Tilapiu are smaller than those taken by the White Pelican. Ecological separation between the two species is achieved through these differences in their feeding behaviour.It is estimated that the White Pelican takes 1201 g and the Pink‐backed Pelican 776 g of fish each day. The total amount of fish eaten by both species from Lake George during 1969 was calculated to be 591 709 kg. This is small (c. 3%) compared with the estimated total fish production of the lake but quite appreciable (12.7%) as a proportion of the total caught by man. It is concluded that the pelican populations are probably not important as a link in the chain whereby organic matter transferred from land to water by the Hippopotamus is returned to the land.
THE UTILIZATION OF GUM TREES BY BIRDS IN AFRICA
Authors: SMITH K. D. 
Published: April 2008

SummaryThe changes brought about by the introduction of Eucalyptus into Africa on the ecology of birds are outlined, in so far as its contribution as a habitat, as a food‐source, and for other uses is concerned. Species known to breed in gums are listed, together with notes on habitat preference, and its limitations in comparison with the indigenous resources are discussed.
RADAR TRACKS OF PALAEARCTIC WADERS DEPARTING FROM THE COAST OF GHANA IN SPRING
Authors: Grimes L. G. 
Published: April 2008

SummaryDuring the northern spring of 1970 and 1971, wader departures were tracked by radar from saltpans on the coast of Ghana near Accra. All but one of the departures headed northeast, and none were directed along the coast. There was a statistically significant difference between the mean heading of April departures (28°± 10°), and May and June departures (41°± 14°). Projected on great circles, all headings were directed towards the known breeding ranges of the wader species wintering at the saltpans.In ten species, the dates of the first returning birds to the saltpans in 1966, 1968 and 1970 were about three weeks earlier than dates recorded in Senegal. It is likely that those reaching Senegal follow a coastal route, whereas waders wintering at the coast of Ghana and eastwards to Nigeria evidently make a crossing of the Sahara both in autumn and spring.
SELECTIVE PREDATION BY TWO SWIFTS AND A SWALLOW IN CENTRAL AMERICA
Authors: Hespenheide Henry A. 
Published: April 2008

SummarySamples of flying insects were made at three sites and during dry and wet seasons in Costa Rica and at two sites during the wet season in Panama. Compared with these were the diets of three aerially foraging birds: the Band‐rumped Swift Chaetura spinicauda and Rough‐winged Swallow Stelgidopteryx ruficollis in Costa Rica and the Short‐tailed Swift Chaetura brachyura in Panama.Among insects flying, Diptera accounted for between 52 and 75%, with smaller numbers of Hymenoptera (mean = 15%) and Coleoptera (10%). In bird stomach contents, however, Hymenoptera predominated (59–81%), Coleoptera were less common (mean = 18.5%) and Diptera least common (3.4%) of the three orders. The discrepancy between diets and samples of flying insects could not be accounted for solely on the basis of differential digestion. The composition of the swift and swallow diets was similar; there were no significant seasonal differences in the taxonomic composition of the diet of Chaetura spinicauda.Size distributions of beetle prey fitted log‐normal distributions in every case. Mean size of prey was significantly larger than that of insects available in all comparisons. Although there was no seasonal difference in the mean size of prey of Chaetura spinicauda, the variance in prey size, used as a measure of niche width, was significantly larger in the wet than in the dry season. Although insect densities may be higher, foraging time is reduced and the wet season is likely the worse season. This result therefore supports Emlen's hypothesis of narrower niches under optimal conditions and broader niches under suboptimal conditions.For increasing altitude above ground published data show a decrease in the density of insects flying, a decrease in the proportions of taxa favoured by the birds, and a significant decrease in the mean size of beetles. None of these trends can explain the differences between the birds' diets and the samples of flying insects.Preference of prey by these birds is concluded not to be a function of prey size alone, but to involve interaction among prey size, ease of capture, and local density. Because of different flight abilities, insect taxa will differ in ease of capture and, consequently, in mean size preferred by the predator, as well as proportions in the diet. This factor favours Hymenoptera and Coleoptera over Diptera as prey. Local concentrations of winged ants, bees and social wasps, and fig wasps make these prey differentially easy to exploit and explain the preference of Hymenoptera over Coleoptera. Large species of swifts are hypothesized to be the evolutionary consequence of the tendency of aerially foraging birds to exploit local concentrations of single prey species.
THE ULTRASTRUCTURE OF THE AVIAN EGGSHELL
Authors: Becking J. H. 
Published: April 2008

SummaryBy means of scanning electron microscopy the eggshells of a number of passerine and non‐passerine wild birds have been investigated. Details and structures have been shown which were hitherto unrevealed by other methods. As suggested by Schmidt (1962a) and Tyler (1964a, 1966a), there is no crystallographic demarcation between cone and palisade layer. There are many vesicular holes in the palisade layer, the physiological significance of which is not yet understood. Bird groups, sometimes even bird species, show specific features of ultratexture of the eggshell by which, for instance, mimetic cuckoo eggs can be distinguished from the eggs of fosters. Other examples are given in which ultra‐structure provides useful taxonomic evidence.
NEW EVIDENCE OF THE SPECIFIC AFFINITY OF CUCULUS LEPIDUS MÜLLER
Authors: Becking J. H. 
Published: April 2008

SummaryScanning electron microscopy of eggshells of Cuculus lepidus of Java and Cuculus p. poliocephalus of the Asian continent revealed differences in ultra‐structure incompatible with conspecific grouping. Eggshell ultra‐structure, egg‐type and colouration, and host selection of C. lepidus are to a high degree similar to C. saturatus, as are morphological characteristics and vocalizations (discussed elsewhere). It is therefore concluded that C. lepidus is a small tropical form of C. saturatus.The hosts of C. lepidus are Phylloscopus trivirgatus and Seicercus grammiceps in Java, and S. castaniceps in Malaya. In Java there are two breeding seasons of C. lepidus, April‐June and September—October, whereas in Malaya breeding is centred in February‐May. During the second breeding season of C. lepidus on Java conspecific migratory races of C. saturatus occur sympatrically. Of the two migratory races of C. saturatus occurring on Java, the C. s. saturatus appears to be twice as common as the northern race horsfieldi. Collection dates indicate that the former race is more abundant in January and February and C. s. horsfieldi in September—November. Between the three races on Java there is no evidence of genetic exchange; residents are largely isolated by habitat, and wintering migrants are non‐vocal.