bluuebunny/crossref_metadata_2025 huggingface dataset:
NUMBERS OF MEADOW PIPITS ANTHUS PRATENSIS ON MOUNTAIN FARM GRASSLAND IN NORTH WALES IN THE BREEDING SEASON
Authors: SEEL D. C. , WALTON K. C.
Published: April 2008

On c. 15 ha of mountain farm grassland in Wales, during 1972‐75, adult Meadow Pipits were present during March–September (but scarce in August–September). Breeding occurred during late April to late July. Incubation was performed by the female but both sexes fed the nestlings. Adults showed an average annual mortality of 54%.

Adults spent nearly all their time on the ground, but varied in their activities and use of the habitat according to the stage of breeding. Their unobtrusive behaviour had a marked effect on the ease with which they could be observed for a population count. Males were seen on 30% of the days for which they were assumed to be present and were recorded giving song‐displays on 28% of the days when they were actually seen. We conclude that, to count all the birds present on a site, most must be marked, sightings must be carefully mapped and the number of observer days must be at least 20, preferably in April‐May.

The numbers of individually marked (and a few unmarked) birds were determined by mapping them on large‐scale aerial photographs. This gave an average annual density of 48 resident pairs per km2. The average home range was 2.18 ha; this value remained relatively constant from year to year. At low population density individual home ranges were separated from one another, and there was some unoccupied ground, but at high population density the ranges overlapped with one another.
NESTLING DIETS OF PRAIRIE PASSERINE BIRDS AT MATADOR, SASKATCHEWAN, CANADA
Authors: MAHER WILLIAM J.
Published: April 2008

The nestling diets of seven species of grassland passerines were studied from gullet samples collected in 1969–1971 at Matador, Saskatchewan, Canada. Relative population densities on census plots on grazed and ungrazed prairie showed that Horned Lark Eremophila alpestris, McCown's Longspur Calcarius mccownii and Chestnut‐collared Longspur C. ornatus preferred grazed areas and Sprague's Pipit Anthus spragueii, Western Meadowlark, Sturnella neglecta, Savannah Sparrow Passerculus sandwichensis and Baird's Sparrow Ammodramus bairdii preferred ungrazed prairie. Fifteen invertebrate ordinal taxa, and seeds were represented to an important extent in combined gullet contents; but two taxa, Lepidoptera (77% larvae) and grasshoppers (all Acrididae), comprised the bulk of nestling diets. Four grasshopper species contributed 70–100% of grasshoppers eaten in June‐August. Overlap at the family level was also high in several other important prey. Comparison with invertebrate populations of ungrazed prairie showed that the birds ignored some abundant taxa of very small invertebrates, and apparently preferred the two least abundant groups which offered large individual prey items. Average nestling food overlap indices for the season among all species except Savannah Sparrow and Baird's Sparrow, based on taxonomic composition, was 0.85. Overlap was moderate in May and June and became very high in July and August. The number of nestlings reached a peak in June and early July when nestling food overlap was much lower than later in the season. Horned Larks avoid competition by nesting earlier than do the other species, while McCown's Longspur, which depends on grasshoppers for nestling food more than do the other species, tends to breed later in the season than the other species. Finally, data suggest that nestling food may be superabundant.
ASPECTS OF THE BREEDING BIOLOGY OF HERRING GULLS LARUS ARGENTATUS IN URBAN COLONIES
Authors: MONAGHAN PATRICIA
Published: April 2008

Herring Gulls nesting on rooftops in South Shields and Sunderland were observed during 1974–76. These colonies, then around 200 pairs in each town, have expanded rapidly despite culls. Ringing results identified the Forth area as an important source of recruits, and also suggested that females are more likely to breed away from their natal area than males. It is clear from the high breeding success that these towns provide favourable alternatives to more typical breeding sites. The gulls in the towns nest at low densities, other than on flat roofs. Their breeding success, averaging 1.2–1.6 chicks per pair, was higher than that recorded at more typical colonies, and on structurally isolated rooftop sites was almost double that on flat roofs. This high success is attributed to the absence of cannibalism in these small colonies and the lack of territorial aggression at the structurally isolated sites.
DUETTING AND VOCAL RECOGNITION BY ALDABRA WHITE‐THROATED RAILS DRYOLIMNAS CUVIERI ALDABRANUS
Authors: HUXLEY C. R. , WILKINSON R.
Published: April 2008

Sonagrams of duets and solo song of the Aldabra White‐throated Rail are presented and their behavioural contexts and functions noted. Visual inspection of sonagrams suggests that the structure of elements of high intensity song is individually characteristic. Elements of low intensity song are characteristic for some but not all individuals. The elements of medium intensity song are the most variable within individuals, and it is least likely that these could permit individual recognition. However, it is noted that the temporal pattern of delivery of song elements may provide cues for vocal recognition.

Both male and female Aldabra Rails respond to the playback of their mate's song by either approaching the sound source or vocalizing. A greater number of positive responses was given to playbacks of the mate's song than to playbacks of a song of a strange bird of the same sex as the mate. It is suggested that this difference in responsiveness may in part result from a more rapid habituation to unfamiliar song.

The function of duetting in the Aldabra Rail and other tropical rails is discussed. It is considered that the major function of duetting in the Aldabra Rail may be co‐operative territorial defence. The extent and precision of duetting in the Rallidae is considered. It is concluded that precise duetting has not yet been demonstrated in any rail species and that the rates of calling in duets may be internally derived.
A 28‐YEAR STUDY OF BREEDING FULMARS FULMARUS GLACIALIS IN ORKNEY
Authors: DUNNET G. M. , & JANET C. OLLASON , ANDERSON A.
Published: April 2008

Colour‐ringed breeding Fulmars were studied on the island of Eynhallow, Orkney, from 1950 onwards.

During the 28 years, there was an average increase in population size of about 4% (9 birds) per annum, standard deviation 23%, The mean population size was 161 birds, with about 22 new breeders and 26 new nest sites per annum. There were marked fluctuations in numbers of birds and occupied sites per annum, causing deviations from the underlying trend.

Most nest sites were on the coast. The distribution of occupied nests was variable, the most favoured areas changing over the years.

A mean of 46 chicks fledged per annum. The proportion of breeding pairs which fledged a chick varied from 16 to 52% (even though there was no known change in conditions). Success in small areas sometimes differed considerably from that of the island as a whole.

Although most fledglings were ringed, only 3% have returned and bred on Eynhallow. Between 89 and 94% of those which survived to breeding age must have bred elsewhere.

It was concluded that the population size and breeding success of small areas could differ quite markedly from that on a wider scale and could vary quite markedly over the years, facts that have important implications for monitoring of seabird colonies.
SEASONAL INCIDENCE OF BREEDING, MOULT AND LOCAL DISPERSAL OF RED‐BILLED FIREFINCHES LAGONOSTICTA SENEGALA IN ZAMBIA
Authors: Payne Robert B.
Published: April 2008

Red‐billed Firefinches were netted and ringed in Lochinvar National Park, Zambia, in 1972 and 1973 and were netted sporadically through 1975. Most nested from March to May, i.e., in the late rainy season and in the early dry season, though some nested as late as August. Nearly all evidently bred in their first year. Moult generally began after breeding was completed, and the indicated average duration of moult was 3–5‐4 months. The main foods taken at all times of year were seeds of the seasonal grasses Echinochloa colonum and Setaria spp.

Local population densities, estimated by two methods, were in the range 33–86 birds per km2. Ringing results demonstrated overlapping activity ranges in the breeding season. Dispersal movements were non‐directional, and varied up to 14 km. Some ringed birds moved regularly each year between a particular waterhole and a breeding site; other did not move from the site of original ringing. Most dispersal was evident in the dry season (June and July) and in the early rains (October and November). Genetically effective dispersal of young from the site of birth to the site of the first breeding season was up to 6'8 km, and some adults were netted in sites a few kilometres apart in successive breeding seasons. Some dispersing firefinches crossed the song dialect boundaries of the Village Indigobirds.
FORAGING, SEASONALITY AND NESTING OF SEYCHELLES SUNBIRDS NECTARINIA DUSSUMIERI
Authors: Greig‐Smith P. W.
Published: April 2008

Foraging and breeding behaviour of Seychelles Sunbirds Nectarinia dussumieri was studied for a total of four months on six islands in the Seychelles.

Birds obtained nectar from indigenous and introduced plants directly (inserting the bill into the corolla‐tube), perched or hovering, or indirectly (piercing the corolla). Direct methods were used in plants with corolla‐tubes less than 20 mm (the length of birds' bills) and indirect methods in most longer flowers. Flowers with longer corolla‐tubes appeared to be preferred. In feeding groups, birds fed more rapidly if not involved in aggressive interactions, which may reflect defence of feeding areas.

Insects were taken from the foliage of indigenous and introduced trees, using a variety of techniques. Flycatching was most prevalent in small‐leaved species, and upright probing in large‐leaved species. In Calophyllum inophyllum, which held very high densities of insects, hovering was used only in saplings, while other methods were used in both mature trees and saplings.

The percentage of nests that were active declined from September to December‐January, suggesting a peak of breeding during this period, the first part of the northwest monsoon season. Examination of live birds and museum skins showed that wing‐moult occurs chiefly from January‐May, but males on Praslin also moult in August‐September.

Nests varied in conspicuousness, being best hidden on Mahé and Silhouette, the only islands with populations of Seychelles Kestrels Falco araea. Males contributed to the earliest stages of nest building, but all later building, as well as all incubation and most feeding of young was done by females. Both sexes defended the nest area against other birds, especially those attempting to steal nest material. Males advertized by song from prominent perches near nests; females also sang occasionally.

Males are larger in most dimensions than females, but no inter‐island differences were found. The species may have evolved duller plumage and larger size than related species, but this remains uncertain without further evidence on its origins. The clutch of one egg only represents a reduction from the normal clutch size of local mainland congeners.
THE ANNUAL CYCLE IN A TROPICAL WET FOREST HUMMINGBIRD COMMUNITY
Authors: Stiles F. Gary
Published: April 2008

In the Caribbean lowlands of Costa Rica, rainfall is moderately seasonal, although even in the driest month over 100 mm of rain usually fall. Flowering of hummingbird food plants shows a peak in the dry season (February‐April) and another in the early wet season (July‐September), with a severe flower shortage at the end of the rains (November‐December). The dry season peak involves largely canopy epiphytes, the wet season peak large herbs of light gaps and edges and forest understory plants. This study examines the responses of the associated community of 22 species of hummingbirds (of which 13 breed, and 12 are common for at least parts of most years) to these spatial and temporal patterns of resource availability. Nearly all common breeding species show a peak of reproductive activity in the dry season, coinciding with the first flowering peak, followed by a discrete moulting season that coincides with the wet season peak of flowering. Of the three species with extended breeding seasons, the two species of hermit, Phaethornis, show moult‐breeding overlap to varying degrees on an individual basis. In a number of species moult and breeding appear antagonistic. The annual peak of body weight and fat deposits in all species occur during the second flowering peak, approximately corresponding to the moult. The annual minima of body weight and fat occur in the lean season and the breeding season respectively. The lack of concordance of these two possibly reflects the use of muscle protein as a nutrient source during the lean season. Several species show pronounced habitat shifts through the year, with the sexes sometimes occupying different microhabitats, especially during the dry season. At least five species show pronounced seasonal migrations, largely or entirely leaving La Selva for part of the year. Overall hummingbird numbers are greatest early in the rainy season, lowest in the lean season, with the non‐hermits (Trochilinae) showing a more pronounced annual cycle of numbers than the hermits (Phaethorninae). Comparisons with other tropical lowland hummingbird‐flower communities are made with respect to the roles of flowers as proximate and ultimate factors regulating the annual cycles and affecting the population biology of the birds.
THE FOOD AND FEEDING ECOLOGY OF GREY‐HEADED ALBATROSS DIOMEDEA CHRYSOSTOMA AND BLACK‐BROWED ALBATROSS D. MELANOPHRIS
Authors: Prince P. A.
Published: April 2008

The food and feeding ecology of Black‐browed Albatrosses and Grey‐headed Albatrosses was studied from 1975 to 1978 at Bird Island, South Georgia. Two hundred and seventy food samples (averaging 75–85 % by weight of the mean chick feed) were collected from adults of each species in February and March. Chicks of both species received meals of the same size, of which half consisted of liquid. The three major components of the solid diet (krill, squid and fish) were similar for both albatrosses. By weight, fish represented about 35 % of the diet of both species; squid predominated (50 %) in the diet of Grey‐headed Albatross, and krill (40 %) in the diet of Black‐browed Albatross. Lampreys were confined to the Grey‐headed Albatross and, although squid of similar sizes were taken by both species, Black‐browed Albatrosses took a much greater diversity of squid. Each major prey type was associated with a characteristic amount of liquid in the complete samples and only in the case of krill and lamprey was this lipid‐rich.

As these two albatrosses are of similar size, breed over the same period and feed meals of equivalent weight to their chicks at similar intervals, the difference in the composition of the diet is possibly the most significant mechanism of ecological segregation (in the breeding season).

Evidence of the effect of krill shortage in drastically reducing Black‐browed Albatross breeding success is presented to support this. The two species have largely non‐overlapping winter oceanic ranges which are probably also correlated with the distribution of preferred prey.
OBSERVATIONS OF GROUP BEHAVIOUR AND BREEDING BIOLOGY OF THE YELLOW‐BILLED SHRIKE CORVINELLA CORVINA
Authors: Grimes L. G.
Published: April 2008

Yellow‐billed Shrikes were found to live in groups throughout the year. Within the group, each member helped to defend the group's territory, warn against predators and feed the breeding female, nestlings and fledglings.

During the study there was little change in the location of the boundaries and in the areas of the territories occupied by the majority of the groups. The densities of the larger groups were in general two to three times that of smaller groups. Numbers within one group varied by ±24% of the average (12) during a period of three years.

Progeny remained in a group for some years before dispersing, sometimes in parties of the same sex. Both sexes exchanged groups, the females moving on average further than males. During successive periods in the history of a group the representation of the sexes varied from a surplus of females to a surplus of males. In the population as a whole the sex ratio was probably parity.

Only one female bred in a group at a particular time and she alone incubated. Eggs were laid on consecutive days. Breeding started at the height of the dry season; the first peak in egg laying occurred at the beginning of the rains; laying continued through the wet season and ceased usually in August. The most frequent clutch size was four, and varied little within a breeding season or between seasons. The incubation period ranged from 15 to 18 days, the most frequently recorded being 17 days. The nestling period was 19 days. The percentage of total eggs laid that produced fledglings was 25% and yearlings 11%.

Young shrikes were independent in the seventh week, participated in group displays in their tenth week and fed fledglings in their fourteenth week.

The age of first breeding was not discovered. Two females in their sixth year were still helpers in a group at the end of the study.
THE BREEDING BEHAVIOUR A N D FEEDING ECOLOGY OF GREY PHALAROPES PHALAROPUS FULICARIUS IN SVALBARD
Authors: Ridley M. W.
Published: April 2008

A population of about 15 pairs of Grey Phalaropes was studied during one season. Observations were made of behaviour and feeding habits at all stages in breeding.

Females advertized to males with Circle Flights over the breeding grounds, and became gregarious and mutually intolerant during the latter part of the season. Females also took the initiative in courtship, but males defended the pair bond against intruders and incubated the eggs. Pair bonds were believed to be stable until after egg‐laying. Descriptions are given of ritual activities and the context in which they were witnessed. Courtship Touching followed intrusion by a strange female, expelled by the male's Driving Flight. Rattling occured at moments of general excitement. None of these rituals appeared to be pre‐copulatory. A ceremony leading to the selection of a nest site, in which the female takes the initiative, is described for the first time. Females deserted their mates during incubation. A qualitative model is proposed to explain the variability in the time between laying and female desertion, in terms of opportunities for polyandry and risk of nest predation.

For food, the birds depended largely on a rich supply of chironomid midges, though aquatic larvae and spiders were also important, particularly early in the season. Three feeding techniques were distinguished and some assessment was made of the profitability of each, in the light of data on feeding rates.

The mating system (monogamous role reversal) is believed to have evolved from the habit of double‐clutching. It is proposed that a factor in the emancipation of females and their assumption of the courtship initiative is the small size and fragmented distribution of breeding groups, in which sex ratios tend to be unequal.
THE FOODS OF GREAT AND SOOTY SHEARWATERSPUFFINUS GRAVISANDP. GRISEUSIN EASTERN CANADIAN WATERS
Authors: Brown R. G. B. , Barker Susan P. , Gaskin D. E. , Sandeman Margaret R.
Published: April 2008

The foods of Great and Sooty ShearwatersPuffinus gravisandP. griseusare described from birds collected off eastern Canada. There was a broad overlap in diet, but Great Shearwaters tended to take more squid and tough‐bodied fish such as mackerelScomber scombruswhile Sooties took more euphausiidsMeganyctiphanes norvegicaand soft‐bodied fish such as HerringClupea harengus. These differences are apparently related to differences in bill structure and in the degree of adaptation to underwater swimming.

The birds appeared to feed opportunistically on whatever prey was locally available in the size‐range between euphausiids and small fish and squid:Meganyctiphanesoff southwest Nova Scotia, spawning and post‐spawning capelinMallotus villosusoff eastern Newfoundland, and migrating squidIllex illecebrosuson the Grand Bank. Possible factors influencing prey selection are discussed. It is suggested that the timing and routes of the birds' migrations in the North Atlantic are related to the exploitation of such local concentrations.

Despite the overlap in diets, differences in the distributions of the two species rule out the possibility of significant competition for common food resources.
THE BREEDING SEASON OF BIRDS IN THE LOWLAND RAINFOREST AND IN THE MONTANE FOREST OF WEST CAMEROON
Authors: Serle William
Published: April 2008

An analysis is made of over a thousand precise bird breeding records for a forest area in West Cameroon. In the lowland forest there is no universal breeding season although most families have a preferred nesting season. On the other hand. in the montane forest breeding is seasonal and takes place in the drier months. These conclusions are supported by field observations and by the examination of over 5000 birds for gonad state, plumage wear and moult.

The remarkable difference in seasonality between the lowland and montane avifaunas is discussed with reference to climate, particularly to the mist which envelops the montane forest in the rainy season.
THE SOCIAL BEHAVIOUR OF THE DUNNOCK PRUNELLA MODULARIS
Authors: BIRKHEAD M. E.
Published: April 2008

Observations were carried out on a colour‐ringed population of Dunnocks. During the winter, regular feeding groups formed at feeding sites, stable in composition, space and time. Dominance hierarchies formed and were weight related. Males were significantly heavier than females. The mean size of winter home‐ranges was not significantly different from the mean size of breeding territories.

Three categories of breeding territory were established: solitary males, male‐female pairs and pairs plus a male helper. There was one case of a bigamous male plus a helper. Pairs plus a helper had significantly larger territories than pairs alone; however, pairs raised significantly more fledglings. Five pairs produced a total of 23 fledglings, whereas four groups (pairs plus a helper) only produced seven fledglings.
THE ECOLOGY OF THE GREENISH WARBLER PHYLLOSCOPUS TROCHILOIDES IN ITS WINTER QUARTERS
Authors: Price Trevor
Published: April 2008

The 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

The 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

The 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

Kelp 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

This 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

Summer 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

Hummingbirds 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

I 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

The 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

We 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

The 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

The 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.
Response to experimental photoperiods by a migratory bunting, Emberiza melanocephala
Authors: Kumar Vinod , Tewary P. D.
Published: April 2008

Little is known about the effects of photoperiod on avian migrants that visit southeast Asia. In this paper, we report experiments performed on an emberizid finch, the Black‐headed Bunting Emberiza melanocephala, to investigate its photoperiodic responses under artificial photoperiods, and continuous light and darkness.

Two series of experiments were performed with the photosensitive male birds. In the first series, different groups were exposed to seven different artificial photoperiods: 3L/21D, 6L/18D, 8L./16D, 11L/13D, 12L/12D, 15L/9D and 20L/4D, for 30 days. They were weighed and laparotomized at the beginning and end of the experiments. The birds responded to 12L/12D, 15L/9D and 20L/4D, but not to 3L/21D, 6L/18D, 8L/16D and 11L/13D. In the second series, photosensitive birds were placed under continuous light (LL) and dark (DD) conditions for 130 and 90 days. Periodic observations indicated that testicular growth and fattening followed by involution and fat‐depletion had resulted in birds under LL, indicating the onset of photorefractoriness, while DD had no effect either on gonads or fattening in the buntings.

Our results demonstrate that light stimulation is a prerequisite to reproductive and metabolic activities (pre‐migratory and migratory changes, fattening and weight gain) in the Black‐headed Bunting, which has a photoperiodic threshold to these events at between 11 and 12 h daily photoperiods.