bluuebunny/crossref_metadata_2025_split huggingface dataset:
THE EVOLUTION AND SYSTEMATICS OF BEE‐EATERS (MEROPIDAE)
Authors: Fry C. H. 
Published: April 2008

SummaryBehavioural 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 amictaN. athertoniMeropogon forsteniMerops gulorisM. mülleriM. bulockiM. bullockoidesM. pusillus M. variegatus (?loringi, oariegatus, lafresnayii, bangweoloensis)M. oreobatesM. hirundineusM. breweriM. revoiliiM. albicollisM. orientalisM. boehmiM. viridis M. superciliosus (persicus, chrysocercus, superciliosus) M. philippinus (philippinus, salvadorii)M. ornatusM. apiasterM. leschenaultiM. malimbicus M. nubicus (nubicus, nubicoides)
A REVIEW OF THE BIRDS OF GIBRALTAR AND ITS SURROUNDING WATERS
Authors: Lathbury Gerald 
Published: April 2008

SummaryIn 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

SummaryInformation 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.SUMMARYThe 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

SUMMARYThe 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

SUMMARYThe 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

SUMMARYAn 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

SUMMARYEstimates 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

SUMMARYTen 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

SummaryThe 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

SummaryThe 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

SummarySome 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

SummaryPalaearctic 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

SummaryAs 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

SummaryThe 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.