bluuebunny/crossref_metadata_2025 huggingface dataset:
THE FLIGHT OF ALBATROSSES (A COMPUTER SIMULATION)
Authors: Wood C. J.
Published: April 2008

The equations of motion for gliding flight in a wind gradient have been used to study the way in which the albatross can gain height in non‐powered flight against a purely horizontal wind. It is argued that a type of potential and kinetic energy parameter is convenient for the assessment of climbing performance if the kinetic energy term involves the airspeed rather than the absolute velocity. The gradient with height of this parameter shows a maximum value at a particular climb angle for each speed and wind gradient.

Two types of complete flight cycle have been investigated in a logarithmic wind velocity profile having a speed of 15 m/sec at a height of 10 m. The emphasis in the study has been on the possibilities of making progress against the wind. Progress in any other directions is very much easier to achieve.

The first cycle is simple and unidirectional with an upwind dive. Although this leads to a fairly rapid progress against the wind it is shown to be impossible without some power input.

By contrast, the more usual flight cycle which involves a dive in the downwind direction is completed very easily without loss of flying speed. In fact, by diving steeply, sufficient excess airspeed can be gained to permit a very long final upwind glide at low level. This repasses the starting position and thus gives a slow but definite nett progress against the wind.
ECOLOGICAL SEPARATION BETWEEN WHITE AND PINK‐BACKED PELICANS IN THE RUWENZOFU NATIONAL PARK, UGANDA
Authors: Din N. A. , Eltringham S. R.
Published: April 2008

The number and distribution of the White Pelican Pelecanus onocrotalus roseus and the Pink‐backed Pelican P. rufescens were studied in the Ruwenzori National Park, Uganda, by means of aerial surveys carried out at approximately weekly intervals between May 1968 and December 1969.

The White Pelican is migratory and was present in the Park at highest numbers in August 1968 and May 1969 when 2510 and 3927 respectively were recorded. It does not breed within the Park. The Pink‐backed Pelican is resident, with a population averaging about 1350 birds.

Pelicans are distributed in discrete flocks on loafing grounds. Flocks of the White Pelican tend to be bigger than those of the Pink‐backed. Forty‐three loafing grounds were recognized in the Park, and it is shown that there is no difference between the species in the frequentation of these grounds. The areas favoured by both species are characterized by flat, open stretches close to water; steep slopes and heavily vegetated shore‐lines are avoided.

The feeding behaviour was studied by direct observation and through cine‐photography. Only the White Pelican feeds communally in coordinated groups; this species also often feeds singly. The feeding sequence of both species is described, and is divided into four phases:searching, trapping, catching and swallowing. The searching phase lasts about six times longer in the Pink‐backed Pelican than in the White. The White Pelican feeds further from the shore than does the Pink‐backed. There is little difference between the species in the daily feeding pattern. Feeding takes place throughout the day but mostly from dawn to about 10.00 hrs and from 17.00 hrs until dusk. The rest of the day is spent mainly in preening, resting or bathing.

The food of pelicans is exclusively fish. The White Pelican takes mainly large Tilupia, and Haplochromis and fish fry to a lesser extent. The Pink‐backed Pelican feeds largely on fish fry, but Tilapia and Haplochromis are frequently taken and by weight are more important than the fry. However, the Tilapiu are smaller than those taken by the White Pelican. Ecological separation between the two species is achieved through these differences in their feeding behaviour.

It is estimated that the White Pelican takes 1201 g and the Pink‐backed Pelican 776 g of fish each day. The total amount of fish eaten by both species from Lake George during 1969 was calculated to be 591 709 kg. This is small (c. 3%) compared with the estimated total fish production of the lake but quite appreciable (12.7%) as a proportion of the total caught by man. It is concluded that the pelican populations are probably not important as a link in the chain whereby organic matter transferred from land to water by the Hippopotamus is returned to the land.
THE UTILIZATION OF GUM TREES BY BIRDS IN AFRICA
Authors: SMITH K. D.
Published: April 2008

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

During the northern spring of 1970 and 1971, wader departures were tracked by radar from saltpans on the coast of Ghana near Accra. All but one of the departures headed northeast, and none were directed along the coast. There was a statistically significant difference between the mean heading of April departures (28°± 10°), and May and June departures (41°± 14°). Projected on great circles, all headings were directed towards the known breeding ranges of the wader species wintering at the saltpans.

In ten species, the dates of the first returning birds to the saltpans in 1966, 1968 and 1970 were about three weeks earlier than dates recorded in Senegal. It is likely that those reaching Senegal follow a coastal route, whereas waders wintering at the coast of Ghana and eastwards to Nigeria evidently make a crossing of the Sahara both in autumn and spring.
SELECTIVE PREDATION BY TWO SWIFTS AND A SWALLOW IN CENTRAL AMERICA
Authors: Hespenheide Henry A.
Published: April 2008

Samples of flying insects were made at three sites and during dry and wet seasons in Costa Rica and at two sites during the wet season in Panama. Compared with these were the diets of three aerially foraging birds: the Band‐rumped Swift Chaetura spinicauda and Rough‐winged Swallow Stelgidopteryx ruficollis in Costa Rica and the Short‐tailed Swift Chaetura brachyura in Panama.

Among insects flying, Diptera accounted for between 52 and 75%, with smaller numbers of Hymenoptera (mean = 15%) and Coleoptera (10%). In bird stomach contents, however, Hymenoptera predominated (59–81%), Coleoptera were less common (mean = 18.5%) and Diptera least common (3.4%) of the three orders. The discrepancy between diets and samples of flying insects could not be accounted for solely on the basis of differential digestion. The composition of the swift and swallow diets was similar; there were no significant seasonal differences in the taxonomic composition of the diet of Chaetura spinicauda.

Size distributions of beetle prey fitted log‐normal distributions in every case. Mean size of prey was significantly larger than that of insects available in all comparisons. Although there was no seasonal difference in the mean size of prey of Chaetura spinicauda, the variance in prey size, used as a measure of niche width, was significantly larger in the wet than in the dry season. Although insect densities may be higher, foraging time is reduced and the wet season is likely the worse season. This result therefore supports Emlen's hypothesis of narrower niches under optimal conditions and broader niches under suboptimal conditions.

For increasing altitude above ground published data show a decrease in the density of insects flying, a decrease in the proportions of taxa favoured by the birds, and a significant decrease in the mean size of beetles. None of these trends can explain the differences between the birds' diets and the samples of flying insects.

Preference of prey by these birds is concluded not to be a function of prey size alone, but to involve interaction among prey size, ease of capture, and local density. Because of different flight abilities, insect taxa will differ in ease of capture and, consequently, in mean size preferred by the predator, as well as proportions in the diet. This factor favours Hymenoptera and Coleoptera over Diptera as prey. Local concentrations of winged ants, bees and social wasps, and fig wasps make these prey differentially easy to exploit and explain the preference of Hymenoptera over Coleoptera. Large species of swifts are hypothesized to be the evolutionary consequence of the tendency of aerially foraging birds to exploit local concentrations of single prey species.
THE ULTRASTRUCTURE OF THE AVIAN EGGSHELL
Authors: Becking J. H.
Published: April 2008

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

Scanning electron microscopy of eggshells of Cuculus lepidus of Java and Cuculus p. poliocephalus of the Asian continent revealed differences in ultra‐structure incompatible with conspecific grouping. Eggshell ultra‐structure, egg‐type and colouration, and host selection of C. lepidus are to a high degree similar to C. saturatus, as are morphological characteristics and vocalizations (discussed elsewhere). It is therefore concluded that C. lepidus is a small tropical form of C. saturatus.

The hosts of C. lepidus are Phylloscopus trivirgatus and Seicercus grammiceps in Java, and S. castaniceps in Malaya. In Java there are two breeding seasons of C. lepidus, April‐June and September—October, whereas in Malaya breeding is centred in February‐May. During the second breeding season of C. lepidus on Java conspecific migratory races of C. saturatus occur sympatrically. Of the two migratory races of C. saturatus occurring on Java, the C. s. saturatus appears to be twice as common as the northern race horsfieldi. Collection dates indicate that the former race is more abundant in January and February and C. s. horsfieldi in September—November. Between the three races on Java there is no evidence of genetic exchange; residents are largely isolated by habitat, and wintering migrants are non‐vocal.
SEXUAL DIMORPHISM AND DIVERGENCE IN WINTER FORAGING BEHAVIOUR OF THREE‐TOED WOODPECKERS PICOIDES TRIDACTYLUS
Authors: Hogstad Olav
Published: April 2008

Measurements 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

The 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

The 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

Nestling 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

A 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

Blue 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

The 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

Weight 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

Observations 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

We 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

Winter 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

The 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

Additional 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

In 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

Investigations 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

The 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

Recordings 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.
POLYGYNY AND BREEDING ECOLOGY OF THE CETTI'S WARBLER CETTIA CETTI
Authors: BIBBY COLIN J.
Published: April 2008

Male Cetti's Warblers bred simultaneously with up to three females. Harem size was correlated with size of male but not of his territory. Males occupied large usually exclusive ranges and devoted much time to patrolling and singing often far from their nests. Incubation was solely by the female who also provided most to all of the food for the young. Incubation and fledging periods were prolonged compared with similar sized birds but first nests were unusually successful. Polygynously mated females laid larger clutches than monogamous ones. Males with fewer females took a greater share of feeding but chick growth and survival were not impaired by polygyny, nor did foods brought to the young differ accordingly. The existence of this unusual breeding system is discussed with emphasis on the co‐evolution of sexual dimorphism and non‐equal sex ratios resulting from malemale competition. It is postulated that the linear dispersion of its habitat may especially have favoured operation of the Verner‐Orians polygyny model in the evolutionary history of the Cetti's Warbler.
THE BREEDING BEHAVIOUR AND BIOLOGY OF THE SHORT‐BILLED FORM OF THE WHITE‐TAILED BLACK COCKATOO CALYPTORHYNCHUS FUNEREUS
Authors: SAUNDERS D. A.
Published: April 2008

The breeding biology of the short‐billed form of the White‐tailed Black Cockatoo was studied at two main study areas, Coomallo Creek, an area with large tracts of uncleared lands, and Manmanning, an area of extensive clearing with little native vegetation remaining. The study was based on individually marked birds. The actions of females selecting and preparing their nest hollow ensured that other females were kept away from the area of that nest, resulting in nests being spaced out through the study areas.

Eggs were laid between July and November with birds at Manmanning starting about four weeks after those at Coomallo Creek. Clutch size was a maximum of two and incubation took 28–29 days. Hatching success was higher for two‐egg clutches than for one‐egg clutches. There were no differences between fledging success for one‐egg or two‐egg clutches at either area, but fledging success at Manmanning was lower than that of Coomallo Creek.

Rates of growth for weight and length of folded left wing were calculated for nestlings from both areas. These rates of growth were compared within areas between years and between areas within years. There were differences in rates of growth of nestlings from Coomallo Creek compared with those from Manmanning and these differences were related to shortages of food at Manmanning.

The annual survival of tagged adults was calculated at 61–69% and that of juveniles over the first 12 months after fledging at 15%. The survival figures for adults seemed too low and it is suggested that the wearing of wing‐tags may place the individual at a selective disadvantage compared with an untagged individual.
COLONY DESERTION AND REPRODUCTIVE SYNCHRONY OF BLACK‐BILLED GULLS LARUS BULLERI
Authors: EVANS ROGER M.
Published: April 2008

Black‐billed Gulls breeding in large dense colonies on river beds in New Zealand were found to have a high rate of colony desertion early in the nesting cycle. The hypothesis is developed that individuals faced with possible desertion after they have begun to nest can reduce the likelihood of being deserted by delaying their nesting activities until a large number of others is also ready to nest. This interpretation is developed into a graphic model to show that colony desertion can thereby produce a strong selection pressure favouring highly synchronized nesting. This model successfully predicts onset synchrony, subcolony formation, occurrence of complete colony desertions mainly early in the season, occurrence of partial colony desertions, and the existence of nester non‐nester conflict over whether or not to desert. Unstable food appears to be the most likely cause of colony desertion in Black‐billed Gulls.

Black‐billed Gulls are similar, in varying degrees to Sandwich, Royal and White‐fronted Terns. Convergent traits include tendencies to occupy colonies rapidly and synchronously, reduced site tenacity, and the use of open and often unstable nesting habitats. The links described here between desertion and synchrony may be relevant for some other species.
Studies of the courtship behaviour of the Redshank Tringatotanus
Authors: Hale W. G. , Ashcroft R. P.
Published: April 2008

Ground chases are a feature of early breeding season display in the Redshank. Chases usually involve males chasing females in an attempt to copulate. Fights which occur are usually between male and female and not between two males as recorded in most previous literature. On occasions, females will chase interloping males and fight. Chases may give rise to the wing‐lifting, pre‐copulatory ceremony as may the scraping ceremony which serves to attract a female to a scrape. Ground chases occur most frequently at the end of the first week of April and again at the beginning of the third week. The two peaks in activity coincide with similar peaks in the occurrence of display flights and correspond with two physiologically different groups within the population, early and late breeders. Chases occur most frequently around mid‐day.

Scraping takes place mainly in the early breeding season and a single male may produce up to 20 scrapes at this time; later, after egg laying has begun, only a single nest scrape may be produced. The female selects the scrape. Successful copulation does not normally occur until the third week of April and this invariably follows the wing‐lifting ceremony.
The diet of urban Magpies Pica Pica
Authors: Tatner Paul
Published: April 2008

This paper describes the diet of Magpies in the Manchester urban environment, based on analysis of stomach contents, pellets and faecal material. The diet comprised a selection of typical grassland fauna, the majority of which were surface‐dwelling invertebrates. Weevils, click beetles, ground beetles, flies, caterpillars and spiders were common. However, soil‐dwelling animals such as leatherjackets and worms were estimated to form a significant proportion of the weight of food. Vertebrate remains, such as those of the field vole Microtus agrestis and the House Sparrow Passer domesticus, were present at a low frequency. The most common constituents of the nestling diet were invertebrate groups that attained their peak seasonal abundance during the nestling period, which suggests that food resources may be utilized in proportion to their availability. During the winter when invertebrate material is scarce, the diet is largely composed of plant material; Magpies may experience a food shortage at this time of year. The summer diet of the adult is similar to that of nestling Magpies; neither include many eggs or nestlings.
Breeding ecology of the Clay‐coloured Robin Turdus grayi in lowland Panama
Authors: Dyrcz Andrzej
Published: April 2008

The breeding ecology of Clay‐coloured Robins Turdus grayi was studied in 1979 in the former Canal Zone of lowland Panama. Two study areas were chosen close together, Summit Gardens (27‐3 ha), an ecological island of habitat suitable for Clay‐coloured Robin surrounded by forest, and Morgan's Gardens (3–6 ha), a similar island surrounded by deforested areas and settlements. Eighty‐three active nests were found and checked. The breeding season lasted from 2 March to 21 June. In Morgan's Gardens the first broods were raised in the dry season and second broods in the rainy season; in Summit Gardens most broods started at the beginning of the rainy season. In comparison to the closely related Blackbird T. merula in Poland, Clay‐coloured Robins build nests on isolated trees or bushes, usually in more conspicuous sites (interpreted as an anti‐predator adaptation) and on flexible, horizontal branches off the main trunk. Over 45% of broods were destroyed by predators but other factors causing brood loss were negligible. Nests built on palms were considerably safer. In the dry season the predation rate was low (5%) and increased during the course of the rainy season. Unlike Blackbirds, Clay‐coloured Robin nestlings were given a lot of fruit; their diet was diversified. Starvation occurred in 60% of nests although usually only the youngest nestling died. Breeding density in Morgan's Gardens at 50 pairs per 10 ha was much higher than in Summit Gardens at 15>8 pairs per 10 ha. Breeding losses were lower, the nestlings were fed more fruit, the average nestling weight was lower and the production of fledglings per breeding pair was twice as high in Morgan's Gardens. It was concluded that a strategy of settling in a rather overpopulated place with hard foraging conditions but lower predation was better than settling in a area with a better food supply but higher predation.
The breeding ecology and behaviour of Wrens Troglodytes troglodytes under primaeval and secondary conditions
Authors: Wesolowski Tomasz
Published: April 2008

The breeding habits of Wrens inhabiting the primaeval forest of Biatowieza National Park, Poland, are described and compared with those of Wrens living in man‐transformed habitats of Western Europe.

Significant inter‐habitat differences in numbers exist in Biatowieza. On average there are 4‐3 territories per 10 ha in ash‐alder, 1 ‐7 territories per 10 ha in oak–hornbeam and 0–4 territories per 10 ha in coniferous habitats. In ash–alder stands the males have smaller territories, build fewer nests and have better pairing success than in oak–hornbeam stands. However, these two habitats do not differ significantly in average clutch size, timing of breeding or nesting success. Over 80% of nests used for breeding in Biatowieza are situated in uprooted trees. Inter‐habitat differences in bird numbers reflect differences in distribution and density of such trees.

Low numbers of Biatowieza Wrens cannot be accounted for solely by high mortality away from the breeding grounds. Available data strongly suggest that numbers of both sexes are proximately limited by behavioural interactions on the breeding ground.

In west European Wrens, densities are higher, territories smaller, polygyny more frequent, clutches smaller and production of young higher than in Biatowieza. Differences in production of young result from different rates of nest predation. Indirect evidence suggests that the breeding habits of Wrens once living in the primaeval forests of western Europe were similar to those of Biatowieza birds, and that the differences observed nowadays result to a large extent from man‐made transformations of habitat. It is suggested that man's lowering of the predation pressure acting both on proximate (enabling birds to produce more young) and ultimate levels (decreasing relative advantages of dispersed breeding) was the decisive factor allowing an increase in numbers of Wrens in secondary habitats.
Habitat and laying date of Great and Blue Tit Parus major and P. caeruleus
Authors: Dhondt Andre A. , Eyckerman Roman , Moermans Renaat , Hublé Jan
Published: April 2008

Using 19 year's data from nine study areas at Ghent we investigated the effect of habitat on laying date, and found it to be quite different for Great and Blue Tits. In Great Tits we found a clear gradient in laying dates from urban over suburban to rural habitats. Blue Tits laid earliest in a suburban habitat and latest in a rural habitat. All other areas, including urban, suburban and rural ones, formed one intermediate group. The overall average laying date for the Great Tit, 18.9 April, was slightly earlier than that of the Blue Tit, 19.4 April. In urban areas Great Tits laid significantly earlier than Blue Tits, in optimal oak habitat and in one suburban area Blue Tits laid earlier, whereas in the five remaining areas no significant differences between the two species were found.

We argue that the differences in laying dates, although correlated to temperature, are probably caused by differences in the timing of food availability. We suggest that differences in laying dates of Great and Blue Tits are caused by a different response to environmental variations through differences in feeding ecology.
The feeding and breeding ecology of Barn Owls Tyto alba in Peninsular Malaysia
Authors: Lenton Graham M.
Published: April 2008

Barn Owls have only recently colonized Peninsular Malaysia, nesting in the roof spaces of houses in oil palm estates and feeding on the rats which inhabit these plantations. Pellet analysis showed that the prey spectrum was confined almost entirely to three species of the genus Rattus which are the major pests of oil palm. There was no annual variation in diet. Breeding showed a broad seasonality but occurred in all months of the year. Mean clutch and brood sizes of 6.6 and 4.6 respectively were recorded, most pairs producing two broods a year although on two occasions three were raised. Overall hatching success was 69.0% with first clutches more successful (79.9%) than second (57.3%). First broods fledged 86.1% and second broods 69.1% of young fledged. Comparison of growth rates of different sized broods suggested that there is a physiological maximum at which all broods proceed irrespective of brood size. The behaviour al changes needed in hunting techniques when colonizing dense plantations rather than the more usual open habitat of Barn Owls is discussed. The breeding strategy seems to be one of producing large clutches and broods, and frequent breeding attempts in a habitat with a high potential carrying capacity.