bluuebunny/crossref_metadata_2025_split huggingface dataset:
SEXUAL DIMORPHISM AND DIVERGENCE IN WINTER FORAGING BEHAVIOUR OF THREE‐TOED WOODPECKERS PICOIDES TRIDACTYLUS
Authors: Hogstad Olav 
Published: April 2008

SummaryMeasurements of 48 males and 45 females of Three‐toed Woodpeckers shot in Norway revealed that the mean lengths of wing, tail, bill and tarsus of males were significantly greater than those of females. Sexual dimorphism was most marked for the bill and tarsus.Feeding observations of the species from spruce‐dominated mixed forests during the October‐March period indicated an intersexual partitioning of the foraging niche. The males exhibited a stereotyped foraging pattern of bark scaling low down on the main trunks of dead spruce, whilst females used a more differentiated feeding technique and utilized a greater variety of trunk and branch sizes of dead, decaying and living trees of several different species. Significant intersexual differences were found in tree height preference and in the diameter of trunks and branches. The males foraged almost exclusively on the trunks of trees over 10 m high and over 15 cm in diameter, whilst females often frequented dead spruce, under 5 m high, and foraged on thinner trunks and branches. Foraging height was significantly lower for males than for females.The relationship between the sexual dimorphism, the intersexual partitioning of the feeding niche and their biological significance, is briefly discussed.
MOULT OF THE PURPLE SANDPIPER CALIDRIS MARITIMA IN ICELAND
Authors: Morrison R. I. G. 
Published: April 2008

SummaryThe autumn moult pattern of adult Purple Sandpipers Calidris maritima in Iceland is described. The duration of the moult was estimated to be c. 5½‐7 weeks (c. 40–50 days). Females generally started moult before males and moult did not appear to overlap breeding. Information from other areas is reviewed. A mechanism by which the duration of moult is shortened amongst various species is by an increase in the number of feathers growing concurrently during the moult. Likely reasons for the placing of the moult in the annual cycle of the Purple Sandpiper are discussed, and appear to be related to the exceptionally northerly wintering distribution of the species.
MIGRANT SHOREBIRDS IN THE SEYCHELLES
Authors: Feare Christopher J. , High Jeremy 
Published: April 2008

SUMMARYThe aim of this paper was to assess the status of migrant shorebirds in the Seychelles. Most observations were concentrated on two areas: a 6 ha mudflat at Victoria, Mahé, and open areas of Bird Island.A systematic list of all shorebirds that have been recorded in the Seychelles is given, including data on abundance and their incidence on other islands of the Malagasy region. Most of the Seychelles migrants probably originate from the north and east, i.e., the central and eastern Palaearctic, and arrive after a sea‐crossing of over 1600 km.Highest numbers of species and of individuals occurred in the Seychelles during the northern winter, but about one third of the species recorded were also present, in reduced numbers, in the summer. Few birds in breeding plumage were seen; probably most birds, especially those which summered, were immature. Numbers of both summering and wintering birds varied from year to year, these variations probably being related to breeding success at higher latitudes.
ESTABLISHMENT OF WEIGHT HIERARCHIES IN THE BROODS OF HOUSE MARTINS DELICHON URBICA
Authors: BRYANT D. M. 
Published: April 2008

SUMMARYNestling birds may differ in size and weight on the first day a clutch is fully hatched, mainly because eggs within clutches hatch over a period of several days. This asynchronous pattern of hatching is usually thought to facilitate brood reduction when the food supply is unpredictably restricted. The purpose of the study reported here was to examine the contribution of egg‐weight, clutch‐size, hatching spread, food supply and season to weight differences in newly hatched broods of the House Martin.At laying, heavy eggs had a greater moisture and dry weight content than light eggs and immediately before hatching there was a correlation between initial egg‐weight and the dry weight of embryo and yolk. Heavier clutches also tended to give rise to heavier hatchlings. There was, however, no correlation of fresh egg‐weight with the dry weight of embryos alone and the relative dry weight of embryos in a clutch was dependent on laying sequence.Hatching spread (the number of days between the emergence from the egg of the first and the last hatchling of the clutch) was 0.75 ± 0.46 days for clutches of two and increased with the size of the clutch up to 1.80 ± 0.79 days for clutches of five. When food was scarce during laying, hatching spread was greater. Weight difference in newly hatched broods was correlated with hatching spread and moreover in multivariate analysis was also correlated with periods of food scarcity during laying.It was concluded that all examples of weight hierarchies among hatchlings should not be considered adaptive; in some cases they may be imposed by food scarcity. This can lead to mortality of the runs even if food is plentiful. When the weight hierarchy is not adversely accentuated by food scarcity it may function as previously suggested, to allow brood reduction. Alternatively, particularly among House Martins, it may spread out the peak food needs of individual nestlings thereby spreading the demand on the adults.
SEXUAL DIMORPHISM IN RELATION TO WINTER FORAGING AND TERRITORIAL BEHAVIOUR OF THE THREE‐TOED WOODPECKER PICOIDES TRIDACTYLUS AND THREE DENDROCOPOS SPECIES
Authors: HOGSTAD OLAV 
Published: April 2008

SUMMARYA comparison of morphological characters shows that Picoides tridactylus is more markedly sexually dimorphic than Dendrocopus leucotos, D. major or D. minor. This is correlated with intersexual differences in foraging behaviour in P. tridactylus, lacking in the Dendrocopus spp. Apparently as a consequence, the sexes are able to share winter territories among P. tridactylus but not among D. major or D. minor; conclusive observations of D. leucotos were not possible. It is suggested that these differences may reflect the distributional history of the species, and the extent of interspecific competition.
STRUCTURE AND FORAGING PATTERNS OF FLOCKS OF TITS AND ASSOCIATED SPECIES IN AN ENGLISH WOODLAND DURING THE WINTER
Authors: MORSE DOUGLASS H. 
Published: April 2008

SUMMARYBlue Tits were the commonest and most frequent members of mixed‐species insectivorous flocks during the winter at Wytham Wood, Oxford. Six common flocking species (Blue Tit, Longtailed Tit, Great Tit, Coal Tit, Marsh Tit and Golderest) made up nearly two‐thirds of the birds in the study area. A tentative interspecific social dominance hierarehy was constructed: Great Tit > Blue Tit > Marsh Tit > Coal Tit > Long‐tailed Tit and Goldcrest. Blue Tits permitted conspecifics to approach them more closely than did other flock members. Blue Tits most frequently led the flocks, but no more than would be predicted by their abundance. Great Tits, and Marsh Tits and Coal Tits to a lesser extent, defended territories during the winter.Two of the six common species frequented the inner parts of branches (Great Tit, Coal Tit), two the outer parts of branches (Blue Tit, Marsh Tit), and two the twigs (Long‐tailed Tit, Goldcrest). Members of each of these species‐pairs showed marked differences in height of foraging and/or species of tree frequented. Because of their abundance, the impact of Blue Tits outside of their most highly frequented foraging zones may exceed that of species concentrating in these other zones (e. g., twigs high in trees). The Coal Tit foraged most diversely, the Great Tit least diversely. Species that foraged diversely in one of the three foraging categories (species of tree, substrate, height) usually foraged less diversely than most other species in the other dimensions. Species usually overlapped least in the zones exploited (inner parts of branches, etc.). Great Tits overlapped with other species less than did any other common flock member, and Coal Tits were the next lowest in this regard.
FACTORS AFFECTING THE FOOD SUPPLY AND BREEDING SEASON OF RESIDENT BIRDS AND MOVEMENTS OF PALAEARCTIC MIGRANTS IN A TROPICAL AFRICAN SAVANNAH
Authors: SINCLAIR A. R. E. 
Published: April 2008

SUMMARYThe fact that Palaearctic migrants arrive in the northern tropical savannah of Africa during the dry season suggests potential competition for food with African species. Moreover, in the southern tropical savannah African species breed during the rainy seasons, when Palaearctic migrants are present.In the equatorial area of Serengeti, East Africa, an index of the food supply for insectivorous birds was obtained from 3 years of light‐trap measurements and sweep net samples. Adults of Lepidoptera, Coleoptera, Orthoptera and Isoptera are sparse in the dry season but become locally abundant after the first rainstorms that mark its close. They are apparently blown by converging winds ahead of the inter‐tropical front and settle to lay eggs where rain has fallen. These early storms therefore produce localized superabundances of food. In the ensuing rainy seasons insect abundance remains high.African insectivorous birds breed during the wet period, reaching a peak two months after the insect increase. It is suggested that this lag is due to the need to recover body condition, build up reserves for eggs, develop gonads and wait for vegetation and insect larvae to develop. In the samples available, breeding records of above‐ground nesters peaked in the first rains, while ground‐nesters peaked in the second (main) rains. Predators bred towards the end of the rains, when there is an abundance of fledglings and small mammals. Thus the food supply could act as the ultimate factor determining the timing of the breeding season in this area.Palaearctic migrants arrive in the Serengeti 4–10 weeks ahead of the main rain front. However, most species are only found where rain has fallen recently. When conditions dry up they move on to other wet areas. Thus they overlap with African species only where there is a superabundance of insects. When the rains become widespread Palaearctic migrants disperse into their usual habitats, and therefore appear not to compete for available resources with closely related species of African birds. The situation in West Africa, where residents and migrants overlap throughout the dry season, cannot be explained in the same terms.
SPRING WEIGHTS AND PASSAGE OF SEDGE WARBLERS ACROCEPHALUS SCHOENOBAENUS IN CENTRAL KENYA
Authors: PEARSON D. J. , BACKHURST G. C. , BACKHURST D. E. G. 
Published: April 2008

SUMMARYWeight and other data were collected on over 1300 Sedge Warblers Acrocephalus schoenobaenus in central Kenya, mainly during spring (April‐May). The weight, fattening rate and length of stay of spring passage birds varied from one site to another. In scrub and thicket at Kariobangi, Nairobi, passage and new arrival continued each year into May; few birds stayed to fatten, and weights over 16 g (40% above mean winter weight) were practically never recorded. At Lake Nakuru, thousands of birds were present during late April‐early May 1972; many stayed to fatten for 1–3 weeks, and weights over 16 g (maximum 215 g) were not uncommon; new arrivals of lean birds continued into May. At Athi River, in 1971, many of the birds present during mid‐late April stayed 1–2 weeks and fattened rapidly; 20% of all late April weights were in the range 16–21 g. Mean fattening rates at Nakuru and Athi River were 0.31 and 0.64 g/d respectively. The migration strategy and potential flight range of Kenyan spring birds is discussed.Active wing moult was rarely recorded. Most locally wintering birds and spring passage birds were judged to have renewed their plumage during the preceding October‐January.
OBSERVATIONS OF THE MIGRATION OF RAPTORS AND OTHER LARGE SOARING BIRDS IN BULGARIA, 1975–1978
Authors: ROBERTS JOHN LAWTON 
Published: April 2008

SUMMARYObservations are given, from the years 1975 to 1978, on the migrations of raptors and large soaring birds along the Bulgarian section of the Black Sea coast, with casual observations on passage in western and central Bulgaria. The winter status of pelicans, and of some raptors, is discussed.The author's findings suggest that the main spring migration route follows the coast north from Burgas, rather than turning west there, as had been suggested.
THE PROCESS OF COLONY FORMATION AMONG HERRING GULLS LARUS ARGENTATUS NESTING IN NEW JERSEY
Authors: Burger Joanna , Shisler Joseph 
Published: April 2008

SummaryWe examined the pattern of colony occupation and egg‐laying in five colonies of Herring Gulls nesting in New Jersey, U.S.A. Colonies formed from epicentres located in sparse bushes. The number of epicentres related to the number of birds nesting in the colonies. Colonies of over 250 pairs had more than one epicentre, whereas those with under 250 pairs had only one epicentre. Epicentres were not always in the geographical centre of the colonies. New territory‐hunting pairs filled in the epicentre areas, and then nested outside these areas. The egg‐laying pattern followed the settling pattern, but was more synchronous than the settling pattern. There was greater synchrony of egg‐laying within sub‐areas of the colonies than in the colonies as a whole. Further, synchrony correlated with the number of nests in sub‐areas.
WINTER SURVIVAL IN RELATION TO DOMINANCE CLASSES AMONG SILVEREYES ZOSTEROPS LATERALIS CHLOROCEPHALA OF HERON ISLAND, GREAT BARRIER REEF
Authors: Kikkawa Jiro 
Published: April 2008

SummaryWinter survival with respect to dominance classes of 932 individually colour‐ringed Silvereyes was examined on Heron Island, Great Barrier Reef, between 1965 and 1969. The dominants (winning two‐thirds or more of aggressive encounters) had significantly better chances of survival between May and August (southern winter) than other birds. The 1967/68 year group was studied in detail; the young born early in the breeding season contained proportionately more dominants than those born later in the season and dominant birds tended to survive better in winter. Adults in the same period showed no dominance dependent survival. The weight of birds in winter differed between first‐year birds and adults in most cases, but winter mortality within each year‐group was not related to the weight of individual birds in May. However, the dominant class had a smaller proportion of birds losing weight through the winter than other classes, and the dominant adults and the intermediate class of first‐year birds tended to be heavier than others in August. The lengths of wing, tail, tarsus and exposed culmen examined for the 1967/68 year group showed no significant trends in either survival or dominance classes. Better survival of dominant birds is considered to be a consequence of their feeding advantages over others, but the intensity of selection for an ability for dominance may fluctuate from year to year in relation to the population density and distribution and abundance of food supply.
BREEDING PERFORMANCE OF PUFFINS FRATERCULA ARCTICA IN RELATION TO NEST DENSITY, LAYING DATE AND YEAR
Authors: Harris M. P. 
Published: April 2008

SummaryThe paper presents data on the breeding and predation of Puffins in two areas of different nest density within a single colony on Dun, St Kilda group, Outer Hebrides in 1973‐78.Within a season birds laying early had a slightly higher nesting success than birds laying late, but laying date had little influence on the peak and fledging weights of young. The main disadvantage in late laying was a reduced chance of relaying if the first egg was lost.Breeding success and chick weights varied from year to year. The 1974 season was the least successful with the lowest nesting success, lowest frequency of feeds, lowest calorific value of feeds, lightest chicks and slowest growth. Overall breeding performance was not related to the annual mean laying dates.In all years pairs nesting in the area of high nest density did better than pairs nesting at low density. The effect is attributed to differential predation and disturbance by predatory gulls. At least 4.2% of adult Puffins breeding in the area of low burrow density were killed by gulls each breeding season; this is higher than the total annual mortality found in three other studies. Only 0.9% of adults from the high density area were found killed. The subpopulation in the low density area cannot survive without much immigration, yet there is no evidence that this happens.
INFORMATION ON NEW GUINEAN KINGFISHERS, ALCEDINIDAE
Authors: Bell H. L. 
Published: April 2008

SummaryAdditional information on 15 species of New Guinea kingfishers is presented: Alcedo atthis (range, habitat), A. azurea and A. pusilla (ecological separation), Ceyx lepidus (foraging, habitat), Melidora macrorhina (affinities, nocturnal habit), Clytoceyx rex (foraging), Dacelo leachii superflua (treehole nesting), D. tyro (reactions with D. leachii), D. gaudichaud (social organization, antiphonal calling, territory size, habitat), Halcyon torotoro (feeding, defence display), H. nigrocyanea (habitat), H. macleayii and H. sancta (habitat, wintering territory), Tanysiptera dana (habitat), T. Sylvia (distribution of resident and migratory subspecies). Possible ecological separating mechanisms are suggested for the kingfisher community of rainforests. Abundance at one lowland site is discussed.
MOULT OF BUDGERIGARS MELOPSZTTACUS UNDULATUS
Authors: Wyndham Edmund 
Published: April 2008

SummaryIn captive Budgerigars Melopsitticus undulatus moult of primaries started in the middle of the tract and moved progressively inwards and outwards, the inner feathers being replaced faster than the outer ones. Full replacement of primaries took six to eight months and a new cycle of moult usually started before completion of the old cycle. Moult of secondaries followed no clear pattern and occurred less frequently than moult of primaries. Moult of rectrices started with the middle pair and moved progressively outwards on both sides. Complete moult of rectrices took about six months and a new cycle often started before completion of the old. Moult of the head and body occurred intermittently throughout the year. Birds fledged in juvenal plumage, they passed into first basic plumage with a partial moult (head and body feathers) and into definitive basic plumage with a moult of all contour feathers.In the field in inland mid‐eastern Australia, there were some birds replacing feathers and some with complete plumage in most months of the year. Birds with complete plumage may have been between moults or within a moult and between replacement of feathers. The proportion of birds in moult did not increase in intensity after breeding, or cease during breeding or before movements. Some birds of both sexes with gonads in a reproductive condition were replacing feathers. Rirds that were replacing feathers had similar lipid deposits to birds that had a complete plumage.
WINTER FEEDING ECOLOGY OF WIGEON ANAS PENELOPE AT THE OUSE WASHES, ENGLAND
Authors: von Känel Angela 
Published: April 2008

SummaryInvestigations on the feeding ecology of Wigeon were carried out in winter 1978–79 at the species' most important inland wintering habitat in Britain. The study area included 287 ha of grassland, about one‐sixth of the Washes, which is grazed by cattle and sheep until late autumn. In winter the area is partly or fully flooded. The number of Wigeon increased to 11 200 in January but cold weather in February, with snow and frozen flood water, forced the birds to leave, only 600 staying in the reserve. In March up to 4000 birds were again present.The distribution of the population within the refuge depends on whether the habitat is dry pasture with only a few ponds, partly flooded, fully flooded or covered with snow and frozen flood water. Under dry or slightly wet conditions 98% of the Wigeon were grazing (October to January), while under partly flooded conditions (February and March) 42%, fed on water. With increasing water depth, upending was used by 13%, while 45% of the population moved to the barrier banks, grazing there in March. The feeding method can change within a few hours with increasing water depth.The diurnal activity pattern varies during the wintering period. A lower percentage of morning feeding occurred after flights back from feeding outside the refuge and under frozen conditions. The feeding activity was higher at mid‐day with a slight decrease towards dusk. The average diurnal feeding activity was 71% (October to April), with a maximum of 90% in November.Wigeon feed diurnally and nocturnally. During a 24 h period in March they were foraging for 15 h 40 min; by day 81% of the time was spent feeding, while at night only 48%.Standing crop measurements showed that the biomass of green vegetation declined significantly outside enclosures due to Wigeon usage. Pasture land should be grazed at different intensities by cattle and sheep before the arrival of the ducks. Inland reserves should include such pasture together with some standing water where the birds are undisturbed. The use of inland pastures can compensate for the loss of coastal habitats.
DIET AND DISPERSION OF THE GREAT ARGUS ARGUSIANUS ARGUS
Authors: Davison G. W. H. 
Published: April 2008

SummaryThe food and dispersion of Great Argus were studied in two West Malaysian forested areas from 1975 to 1978. Invertebrates on the litter surface lived at low density and were typically large and solitary; those beneath the litter were abundant but typically tiny and colonial. Great Argus feed mainly on fallen fruit but rely for protein on the large, solitary litter‐surface invertebrates and were never seen scratching for food.Adult males maintain small, discrete home ranges in which they forage alone. Much of their time is spent resting, which reduces energy expenditure. Females also forage alone and may be similarly inactive. Great Argus are very large and their requisite large invertebrate prey cannot be obtained beneath the litter; scratching has been eliminated as a foraging technique. A strategy of litter‐surface searching necessitates solitariness, to avoid intraspecific feeding competition. The large size of Great Argus is related to a low rate of energy turnover and energy conservation by prolonged resting. Both sexes are probably territorial during the breeding season and larger territories then may limit population density.
THE SOUND SIGNALS OF THE ADULT AVOCET RECURVIROSTRA A VOSETTA DURING THE PERINATAL PHASE
Authors: ADRET P. 
Published: April 2008

SummaryRecordings of Avocet vocalizations were collected from three pairs, using a microphone placed close to nests at the end of incubation in a colony on the French Atlantic coast, in Vendée.From sonagraphic analyses, ten vocal structures were identified and described. Particular attention is given to the internal components of each call in an attempt to demonstrate structural relationships. In terms of general melodic features, three vocal groups are identified: chuckle calls, ascending chirping calls and sustained calls with whistled components. The existence of numerous gradation forms is emphasized.Verification of gestural behaviour at the time of the recordings additionally allows the context of emission to be clarified. It is distinguished thus: parental calls, calls concerned in the maintenance of individual distance and calls produced in the presence of predators.Finally, the Avocet sound signals are compared with those of other species, mainly waders.