bluuebunny/crossref_metadata_2025_split huggingface dataset:
THE ECOLOGY OF THE GREENISH WARBLER PHYLLOSCOPUS TROCHILOIDES IN ITS WINTER QUARTERS
Authors: Price Trevor 
Published: April 2008

SummaryThe Greenish Warbler is an abundant entirely insectivorous Pafaearctic migrant wintering in the tropical deciduous forests of India and east Asia. A population was studied at one locality in the eastern Ghats of south India over one winter, with a short return the following winter. Individuals maintain, and annually re‐occupy, territories throughout their seven or eight months stay. A general account of territorial behaviour is given.There is much evidence that food is critically short, particularly during the months of December to February and March, which coincides with the end of the dry season. Because of the short duration of the study, there are shortcomings in data presented. Nevertheless there is evidence that territories vary severalfold in quality and individual birds' behaviour and survival probability are correlated with this. It is suggested that territorial behaviour is the best individual strategy for long‐term resource management. The presence of food competitors can alter this behaviour, much as changes in food dispersion are known to. The ability to control return time to a patch as a subsidiary function for territoriality is briefly discussed.
COOPERATIVE BREEDING OF THE NORTHWESTERN CROWCORVUS CAURINUSIN BRITISH COLUMBIA
Authors: Verbeek Nicolaas A. M. , Butler Robert W. 
Published: April 2008

SummaryThe behaviour of helpers at nests of Northwestern Crows was studied on Mandarte Island and Mitlenatch Island, British Columbia. Not all nests had a helper and there was only one helper per nest. Helpers participated in varying degrees in the defence of the territory and nest, feeding of the nestlings and fledglings and they cached food on the territory. Adult males fed helpers, and helpers obtained most of their food on the adults' territory. Adults with helpers laid larger clutches and produced more fledglings per nest than adults without helpers. It is suggested that cooperative breeding in the Northwestern Crow is of recent origin.
ECOLOGY OF THE RED‐NECKED FALCON FALCO CHICQUERA IN ZAMBIA
Authors: Osborne Timothy O. 
Published: April 2008

SummaryThe Red‐necked Falcon in southern Zambia is a year‐long resident in its breeding territory. The study was conducted on a floodplain and the adjacent acacia savannah in an undisturbed natural environment. The falcon principally nests in natural depressions on frond bases on the leeward side of Borassus Palms but also utilizes old crow and raptor nests. Incubation averaged 33 days and was undertaken by the female. The young fledged after a 36‐day nestling period and remained under parental care for up to three weeks after that. Nesting success averaged 1.3 young per nest or 44% of the eggs laid. The post‐juvenal moult commenced when the young were five to six months old and continued for six months. Birds comprised 98% of the diet of the falcons. The adults selected larger prey as the nestlings increased in size. The 69‐day incubation and nesting period is up to 14 days longer than in similar‐sized falcons.
COLONY AND HABITAT SELECTION OF SIX KELP GULL LARUS DOMINICANUS COLONIES IN SOUTH AFRICA
Authors: Burger Joanna , Gochfeld Michael 
Published: April 2008

SummaryKelp Gulls nested in six colonies on rocky islands, sand and rock cliffs, sand dunes and on a sand, gravel island in a salt lake. The colony sites selected were different from the surrounding areas and were generally inaccessible to ground predators. Kelp Gulls nested in a wide variety of habitats. Within colonies, the gulls did not nest randomly with respect to habitats but preferred to nest on flat, stable areas with some cover (either rocks or vegetation). They generally avoided heavily vegetated areas, areas devoid of vegetation and areas with steep slopes. Their specific habitat choices relate to predation and cannibalism pressures. Intermediate cover provides adequate protection for chicks while allowing for increased visibility and open escape routes for parents. Nearest neighbour distances were similar among colonies and habitats, indicating strong social attraction.
WINTER ROOSTING AND FEEDING BEHAVIOUR OF PIED WAGTAILS MOTACZLLA ALBA NEAR OXFORD, ENGLAND
Authors: Fleming Theodore H. 
Published: April 2008

SummaryThis study presents data on the roosting and feeding behaviour of Pied Wagtails around Oxford, England. During the winter of 1977–78, from two to 1200 wagtails roosted in a Phragmites reed‐bed. Use of this roost was greatest during mild, windless weather and the birds apparently used alternate roosts during harsh weather. Movement between roosts sometimes occurred between sunset and sunrise. Morning ‘departure group’ size, number leaving per unit time and diversity of departure directions increased with roost size. Wagtails quickly left the vicinity in the morning. In the afternoon, they joined one or more pre‐roost gatherings before entering the roost for the night. Behaviour upon arrival at the roost was variable: birds might enter the reeds quickly or circle in large groups before landing. Aerial revolutions and generally ‘restless’ behaviour often accompanied increases in roost size.Wagtail feeding rates varied significantly between and within habitats. Number of wagtails feeding on the flooded Port Meadow, located 2–3 km south of the main roost, varied from about five to over 60 on different days; these numbers were not correlated with feeding rates. In contrast, the number of birds feeding at a sewage farm was nearly constant all winter. Some wagtails show high fidelity to feeding areas but others do not. Five short‐term food supplementation experiments indicated that wagtails knowledgeable about a dense food source are not followed in the morning by naive birds.Results of this study are discussed in relation to the predation, physiology and information centre hypotheses that have been suggested to explain communal roosting in birds. I conclude that the communal roosting system of Pied Wagtails has physiological and anti‐predator functions. Wagtails appear to choose certain roosts because of the protection that they provide from adverse climate and predation.
LAND USE AND SUMMER BIRD POPULATIONS IN NORTHWESTERN GALICIA, SPAIN
Authors: BONGIORNO SALVATORE F. 
Published: April 2008

SummarySummer bird populations were studied in ten sites: two heathlands, two maritime pine Pinus pinaster plantations, one, four, seven and 13‐year‐old eucalypt Eucalyptus globulus plantations, one climax oak Quercus robur woodland, and a farmland area in northwestern Galicia, Spain. The farmland and oak wood contained the greatest number of species (24 and 17 respectively) while the one and four‐year‐old eucalypt stands contained the fewest species (four and six respectively). Avian density was highest in the oak wood (93 birds/ 10 ha) and lowest in a heathland site, the four and one‐year‐old eucalypt stands (26,13, and seven bird/10 ha respectively). The wren was the most widespread and dominant species occurring in all study areas except the one‐year‐old eucalypt stand. Mean bird species diversity for the four eucalypt stands was significantly lower than mean bird species diversity for the other wooded habitats. The avian communities of the heathlands, maritime pine and eucalypt plantations, in contrast to the oak wood and farmland, show an excessively high dominance of one species. Using avian dominance as a biological index of habitat perturbation suggests that over half the landscape (4000 km2) in northwestern Galicia is suffering from chronic stress. The newest stress to the avifauna in a long history of land exploitation by man is the importation and cultivation on grand scale of eucalypts. Balancing this tendency, traditional, small‐scale farming on the mountainous terrain leads to the development of many tiny parcels whose average size is 0.28 ha; this in turn creates much ‘edge’ in hedgerow which serves to maintain a relatively rich avian species diversity in farmland.
COMPETITION BETWEEN HERMIT HUMMINGBIRDS PHAETHORNINAE AND INSECTS FOR NECTAR IN A COSTA RICAN RAIN FOREST
Authors: GILL FRANK B. , MACK ANDREW L. , RAY RUSSELL T. 
Published: April 2008

SummaryHummingbirds in the tropical rainforests of southwestern Costa Rica face intense competition from stingless bees Trigona that steal nectar from hummingbird flowers. Here we document both interference and exploitative competition between bees and hummingbirds at scarlet, hummingbird pollinated flowers of Passiflora vitifolia. Aggressive stingless bees prevented Long‐tailed Hermit Hummingbirds Phaethornis superciliosus from feeding at nearly one‐third of the passion flowers approached. In exclusion experiments, bees and hummingbirds each removed most of the nectar from treated flowers. Experimental exclusion of bees also increased hummingbird use of both natural and artificial flowers.
BREEDING OF THE GREY WARBLER GERYGONE IGATA AT KAIKOURA, NEW ZEALAND
Authors: GILL BRIAN J. 
Published: April 2008

SummaryI studied the breeding of Grey Warblers Gerygone igata (Muscicapidae: Acanthizinae) in forest near Kaikoura, New Zealand, between 1976 and 1979. Only males sang and singing occurred all year. From late July to January pairs defended self‐contained territories of 0·25–1·73 ha but they occupied larger home ranges when not breeding. Territorial adults were strictly sedentary all year. The average annual mortality of breeding adults was 18·5% and the predicted life‐expectancy 4·9 years, which is remarkable in a bird weighing 6–7 g.The breeding season from first building to last fledging was six months long and it began early. Exceptionally, Grey Warblers may build and lay before the shortest day. As the season progressed warblers nested lower on average, both in absolute terms and relative to the tree nested in and canopy at the site. Warblers built in 7–27 days then delayed up to eight days before laying. Only females built and at no stage of breeding did males feed their mates. Both sexes fed the young.Grey Warblers laid for 15–16 weeks of the year and first clutches were laid asynchronously during 5–6 weeks. Eggs of a clutch appeared at two‐day intervals and each egg weighed 1·5 g when fresh (23% of mean adult weight). Clutch size was nearly constant (mean 3·9, mode 4, range 3–5). The incubation period was 17–21 days (mean 19·5 days) and the nestling period 15–19 days (mean 17·2 days). On average the clutch hatched over 1·4 days, even though incubation commenced with the laying of the last egg.Nestlings reached maximum weight on Days 13–14 on average and then receded in weight by 4%, apparently through loss of water. All healthy nestlings exceeded mean adult weight during development by up to 39%. Nestlings from broods of two were at first lighter on average than those from larger broods, but in the second half of the nestling period twins were significantly the heaviest.Grey Warblers were fed for 28–35 days after fledging and they survived well while dependent on parents. Fledglings dispersed up to 3 km or more at independence and only 5% per annum joined the breeding population.Of nests that received eggs, 42% produced at least one fledgling. On average each breeding adult raised 2·0 fledglings per season. Of 265 eggs in 73 nests 70% hatched and 38% produced fledglings. Of 185 nestlings 54% fledged. Probably the main cause of mortality of eggs and nestlings was predation by introduced rodents and mustelids.Grey Warblers raise two small broods slowly during a long breeding season, rather than investing in one large quickly‐reared brood. In New Zealand's mild climate the warbler's food supply may not decline severely in winter, and the population of warblers may remain so close to the limit set by food that extra for breeding is hard to obtain. Thus the breeding strategy may be adapted to a restricted food supply.
THE LITTLE CURLEW NUMENIUS MINUTUS IN SIBERIA
Authors: LABUTIN Y. V. , LEONOVITCH V. V. , VEPRINTSEV B. N. 
Published: April 2008

SummaryThe Little Curlew, closest relative of the Eskimo Curlew, is a rare bird and has a restricted range in eastern Siberia. Within this range, nesting colonies are scattered and separated by hundreds of kilometres. From three to 30 pairs nest 200–300 m apart and within a radius of 1 km. Some colonies are associated with Golden Eagle nests. Both sexes incubate and eggs hatch in 22–23 days. Nests are found on dry well‐drained slopes of low hills and in glades of sparse woodland of larch and dwarf birch. The display flight is similar to that of the Pintail Snipe but unusual for the genus Numenius. It takes place high in the air; the male flies in circles, utters a fluting trill and plunges downwards producing a drumming sound. The Little Curlew has a breeding‐ground repertoire of at least six different sounds. In contrast to the Eskimo Curlew, which is a purely tundra species, the Little Curlew inhabits sparse larchwoods on the slopes of low hills. At the present, the Little Curlew is not in danger of extinction.
FOOD RESOURCES, TERRITORY DENSITY AND REPRODUCTIVE SUCCESS OF AN ISLAND SILVEREYE POPULATION ZOSTEROPS LATERALIS
Authors: CATTERALL CARLA P. , WYATT W. S. , HENDERSON L. J. 
Published: April 2008

SummaryWe examined the relationships between food resources, territory density and some breeding parameters (individual reproductive success and parental age) of a Capricorn Silvereye population during two years' detailed study on Heron Island, Great Barrier Reef. The territorial behaviour of the Silvereyes included dawn song. aggression and distinctive vocalizations. During both years, about 85% of pairs occupied territories although the population sizes differed. The dispersion pattern of territories was not regular and was correlated with the density of figs and human food scraps.Nestlings were fed more figs as they grew, and the parents foraged in fig trees outside their territories. However, only about 60%, of territorial pairs fledged young. Pairs which fledged most young were older, fed more insects to their nestlings, and nested in areas containing more fruiting fig trees per territory.We conclude that food resources were in short supply, and that access to fig trees provided breeding birds with a quick energy source while they searched for insect protein for the young. The data are consistent with the predictions of the ‘sufficient resource‘ hypothesis of the adaptive significance of territoriality but not with its assumption that the principal benefit is the food within the territory.
PAIR FORMATION AND PAIR MAINTENANCE IN THE REDSHANK TRINGA TOTANUS
Authors: HALE W. G. , ASHCROFT R. P. 
Published: April 2008

SummaryThe percentage (45.6%) of colour‐marked Redshanks which return to Banks Marsh NNR retain the pair from the previous year. whilst 6.9% of the previous year's pairs separate and take new mates. In 29.8%, of the previous year's pairs only the male returns and in 17.7%, only the female returns. Usually pairs are established by the male performing a display flight and pair maintenance is facilitated by means of an alighting ceremony. Two main peaks occur in the performance of these displays which are associated with two physiological groups within the population. early and late breeders.
RECENT POPULATION TRENDS IN CLIFF‐BREEDING SEABIRDS IN BRITAIN & IRELAND
Authors: STOWE T. J. 
Published: April 2008

SummaryThe findings of an annual sample census of four species of cliff‐breeding seabirds at study plots in selected British and Irish colonies are presented. The numbers of Guillemot and, to a lesser degree, Razorbill were found to be increasing significantly at most study plots in north and east Britain. With the exception of one Razorbill study plot in Orkney, the only declines detected in these species were in a few colonies in southwest Wales and west Ireland. The magnitude and direction of changes in Kittiwake numbers at study plots showed much local and regional variation, notably in marked decreases in the majority of study plots in Orkney and increases in northwest Ireland. The few data for Fulmar indicate continuing increases in several areas.The results have shown that the census is capable of measuring accurately changes of small magnitude. The problem of whether study plots can be used to infer colony and population change is discussed and comparison made with the findings of other census work.
Energy costs of incubation in the Wandering Albatross Diomedea exulans
Authors: CROXALL J. P. , RICKETTS C. 
Published: April 2008

The role of the sexes in incubation, their changes in body weight and associated energy costs were studied in the Wandering Albatross at South Georgia. Males incubate significantly more than females (54%, range 36–68%) and lose weight during incubation shifts at a greater absolute, but smaller proportional, rate. On average this results in both sexes losing equal proportions of body weight during typical shifts. Energy costs of incubation are calculated to lie between 1.2 and 2.0 times basal metabolism, and probably much closer to the former.All males and most females gained weight while at sea between shifts, most males doing so faster than females. On average both sexes are able at least to maintain body weight during the incubation period. More extreme individuals, however, may end incubation in poor condition and can probably redress this only by neglecting their chick. Chicks that died were more likely to have had parents with a less equal division of incubation duties.
Brood‐parasitism by the Shining Cuckoo Chrysococcyx lucidus at Kaikoura, New Zealand
Authors: Gill Brian J. 
Published: April 2008

For three seasons starting in 1976 I studied the breeding of Shining Cuckoos Chrysococcyx lucidus in forest near Kaikoura, New Zealand. There is no evidence that the cuckoo parasitizes any host on mainland New Zealand other than the Grey Warbler Gerygone igata. A nestling cuckoo returned to within 1 km of its natal site in a subsequent breeding season, presumably after migrating beyond New Zealand. Empirical and theoretical estimates of the area occupied by Shining Cuckoos while breeding are given. Cuckoos near Kaikoura laid during ten weeks, the modal week of laying following seven weeks after the presumed peak of arrival of birds in New Zealand. First clutches of the host escaped parasitism because they were laid before most cuckoos arrived. Parasitized clutches received one cuckoo egg which replaced a host's egg. It was laid before, just after or long after the host began incubating, and mimicry was lacking. Cuckoo eggs, which were about 8% of the adult cuckoo's weight, hatched in 14–17 days. The frequency of parasitism near Kaikoura was 55% of late clutches (n = 40).At 3–7 days old, nestling Shining Cuckoos evicted from the nest all other contents. The nestling period was at least 19 days. Growth in weight followed a logistic curve and the equation is given. Just over half the cuckoo eggs produced fledglings. The effect of brood‐parasitism on the Grey Warbler's productivity was small. Only 17% of late warbler eggs, and late eggs only, were prevented by parasitism from yielding fledglings. Late laying by some Shining Cuckoos (relative to the host's incubational cycle), and late eviction, often led to brief inter‐specific competition among nestlings for food. The brief coexistence of young Warblers and Cuckoos in the nest may explain the apparent mimicry by newly‐hatched Shining Cuckoos of the host's young.
Biology and survival of the immature Puffin Fratercula arctica
Authors: Harris M. P. 
Published: April 2008

The biology and survival of Puffins were studied in northeast Scotland. Puffins usually bred first when aged four or five years but returned for several seasons prior to this. Young birds were probably prevented from returning earlier in the season because they moult their primaries in the spring and early summer. As they got older, they came to the colony earlier in the year, displayed and tried to get a burrow. Younger immatures may summer in specific areas away from the colonies.Many immatures visited colonies other than where they were hatched. This was particularly marked in July of their third year. Up to 23% of Puffins of both sexes permanently emigrated and it is suggested that such behaviour is widespread among auks.About 60 % of fledglings returned to the natal colonies and 30% of fledglings appeared to reach breeding age (although the true figure will be higher as this does not include birds which emigrated). Adult survival was c.96% per annum. The population could theoretically increase by c.7% but the observed rate of increase was c.9% per annum.
Predation by mustelids and rodents on the eggs and chicks of native and introduced birds in Kowhai Bush, New Zealand
Authors: Moors P. J. 
Published: April 2008

Prior to human settlement the endemic New Zealand avifauna evolved in the absence of mammalian predators. Subsequently mustelids, rodents and feral cats have become established and frequently prey on birds and nests. It has been suggested that, because of their evolutionary history, the endemic birds are especially susceptible to such predators. In this paper predation by mustelids and rodents on the eggs and nestlings of eight species of native bird is compared with that on five species of introduced European passerine inhabiting the same lowland forest.Final outcomes were known for 101 nests of native birds and 48 nests of introduced birds found during three breeding seasons. There was no significant difference between the two groups in frequency of predation. Native birds lost 70‐1% of their nests to predators and introduced birds 64‐6%. Most predations occurred during the egg stage. Clutch size did not influence frequency of predation, but brood size did for Fantails and introduced birds. Stoats and weasels were responsible for 77‐9% of predations on native birds and 77‐4% on introduced birds; corresponding percentages for rodents (principally ship rats) were 14‐7% and 19‐4%. Mustelids destroyed proportionately more nests with chicks than with eggs, whereas rodents did the reverse. Predation on both groups of birds was not influenced by their nesting habitat, the species of tree used for nesting, or the height and position of the nest. The vulnerability to introduced predators of native New Zealand birds is discussed in relation to the historical declines of many species, and also their life‐history patterns.
Optimal locomotion modes of foraging birds in trees
Authors: Norberg R. Åke 
Published: April 2008

This paper compares the energy costs of various modes of locomotion of birds foraging in trees. For birds moving vertically in trees by climbing and hopping (but not by flying) the best choice of locomotion mode depends on the distance between visited trees in relation to the height h of the zone searched for food in trees.When the distance between successively visisted trees is longer than about half the distance coverable in gliding flight with height loss h, then it is cheapest in energy to hop or climb upwards in a tree and fly downwards to the next tree. When the distance between successively visited trees is shorter than about half the distance coverable in gliding flight with height loss h, then it is cheapest in energy to move alternately downwards and upwards in trees (downwards in the first, upwards in the second, downwards in the third tree, etc.) and to fly level between trees.Treecreepers and woodpeckers are adapted morphologically to the former mode, but more generalized tree foragers might use either mode depending on the spacing of trees.