bluuebunny/crossref_metadata_2025 huggingface dataset:
SEXUAL AND SEASONAL, VARIATION IN CONDITION AND SURVIVAL OF SWEDISH GOSHAWKS ACCIPITER GENTILIS
Authors: Marcström Vidar , Kenward Robert
Published: April 2008

Winglength was the most powerful intersex discriminator, giving 99.5% separation by itself and 100% combined with bodyweight or keel length. Females but not males, had longer wings and were heavier as adults than as juveniles. Pectoral fat and muscle indices explained 81–91% of variation in total fat and 93–96% of variation in total lean dry weight for male and female hawks but bodyweight change explained only 56–60% of variation in the fat index compared with 75–76% for pectoral lean dry weight. The best size index, keel length, explained only 6.4% of bodyweight variation in males and 11.2% in females. Winglength was very weakly correlated with keel length.

Taking size difference into account, females were heavier with higher wingloading than males but had relatively lighter flight muscles and therefore a lower power availability relative to their flight requirements than in males. On the other hand, females had greater maximum fat stores (17% of bodyweight) than males (14%) and could have survived longer than males without food. These differences would be adaptive for the different role of each sex during breeding.

The weight of first capture of live‐trapped adults and juveniles increased between September and December, possibly because moulting (in adults) or hunting inexperience (in juveniles) kept weights low in autumn but also perhaps because the benefit of having large reserves for surviving, relative to the cost of decreased agility in flight because of increased wingloading, was greatest in mid‐winter. Shot hawks weighed more than the live‐trapped birds but showed the same trends, as did retrapped individuals.

Females but not males, tended to lose weight in January before a further increase in the spring. Records of hawks retaken more than two months after first capture showed that between October and January survival in females but not males, was enhanced by high bodyweight. Since female weights were also significantly lower in southern Sweden than in central and northern areas, it is suggested that changing agriculture or other factors in the south may have reduced prey for females more than for males.
SONG DEVELOPMENT IN CHFFINCHES: WHAT IS LEARNT AND WHEN?
Authors: SLATER P. J. B. , INCE S. A.
Published: April 2008

Male Chaffinches share no more songs with territorial neighbours than would be expected by chance, suggesting that some song learning occurs before young birds set up their territories. Hand‐reared birds are capable of learning song both in their first spring and in the previous summer one young bird produced a good copy of a song which he had only heard as a nestling and fledgling eight months previously. While song learning involves accurate copying of individual elements, the variation in number in elements in a phrase and the temporal pattern of singing shown by hand‐reared birds were similar to that of wild birds rather than being influenced by the tutor tapes.
VOCAL AND OTHER BEHAVIOUR OF KENYAN BLACK‐COLLARED BARBETS LYBIUS TORQUATUS
Authors: SHORT L. L. , HORNE J. F. M.
Published: April 2008

We describe 12 visual and six acoustical displays of Black‐collared Barbets, all associated with interactions of these sexually monomorphic barbets in greeting ceremonies and in antiphonal duets. Certain of the displays, e. g., bill directing, smooth posture and chatter calls largely are associated with multiple‐barbet interactions and greeting ceremonies involving more than two barbets, and seem to represent purely agonistic displays. Other displays, most notably the bobbing and floating flight displays, and the tyaw call, are associated with preduet greeting ceremonies involving the presumed pair. In every case duets were performed by a presumed pair, following a greeting ceremony and visual displays accompany the duetting, which usually becomes precisely synchronized after the initial few notes. Four to 17 notes of each of two types, a usually lower pitched, short and mainly double type A note that introduces most duets, and a higher pitched, usually single, clear type B note that often terminates the duet. Variation in the notes and in their tempos within duets suggests no clearly defined temporal indicators for achieving, maintaining, and concluding the duets. The A and B notes cannot yet be assigned to one or other sex and similarity in form and development of the notes, from notes of greeting ceremonies, suggests the possibility that under some circumstances a bird of one sex may be able to deliver notes of either type. The duets are delivered from singing posts within the group's (or pair's) territory and usually only one duet is uttered from a site before the birds shift to another singing post. The duetting is compared with that of other barbets and appears to be among the best synchronized and most precise in the family. Comparisons with non‐barbet duetting species are difficult because of the special habits and ecology of the barbets and uncertainty as to the sexual rôle of the duetters.
THE SELECTION OF TITS PARUS SPP. BY SPARROWHAWKS ACCIPITER NISUS
Authors: GEER TIMOTHY A.
Published: April 2008

Selection of the Wytham Wood population of tits by Sparrowhawks during the tit post‐fledging period was studied over three years. Within three weeks of the median date of tit fledging, juvenile Blue Tits were selected more frequently than juvenile Great Tits but thereafter juvenile Great Tits were selected more frequently; it is suggested that the former was due to greater vulnerability of Blue Tits in the two to three weeks after fledging, and the latter due to changes in availability due to immigration/emigration of juvenile tits. When juvenile tits killed by hawks were compared on the basis of brood and physical characteristics with their cohorts in the entire population and in those surviving to the following year, only one factor, fledging date, was found to have affected selection by hawks. It is believed that this was because hawks selected late fledged young still in family parties in preference to early fledged young which had already become independent of their parents and were foraging in the better cover of the forest canopy. When adults killed by hawks were compared with all adults available for selection on the basis of species, sex, timing of nesting and whether or not they had been born in the wood, the only selection trend found was that male Great Tits were taken more often than females due, possibly, to greater risk of exposure for males while foraging or during territorial behaviour. When compared with availability, juveniles were selected more frequently than adults in only one year, possibly a result of yearly differences in the number of prey available per hawk, the rate of non‐predator related juvenile mortality or unknown hawk hunting strategies. The overall finding of relative non‐selectivity by hawks was attributed to the surprise factor associated with the hunting methods used by Sparrowhawks in woodland.
Individual and age differences in the feeding ecology of Oystercatchers Haematopus ostralegus wintering on the Exe Estuary, Devon
Authors: Goss‐Custard J. D. , Durell S. E. A. LE V. dit
Published: April 2008

The habitats and foods used by a sample of marked individuals and by the whole population of OystercatchersHaematopus ostraleguswintering on the Exe estuary, South Devon, are described. In the spring and early summer, only a few hundred immatures were present. Two thousand adults and several hundred juveniles arrived in late summer from the breeding grounds and remained until the following spring. The majority of the birds were then adults. At low water, most adults fed on the musselMytilus edulisbeds and ate mussels. Most individuals specialised on this prey and ate little else. Some adults fed on mud‐flats and sandflats within the estuary and along the coast, and specialised on a mixture ofNereis diversicolorandScrobicularia planaor onCerastoderma eduleorLittorinaspp. Though some juveniles ate mussels from the time they arrived, most did not. In winter, they tookScrobiculariaon mudflats, earthworms Lumbricidae and leatherjackets Tipulidae larvae in fields andSpisulaand mussels along the coast. At other times of year they mainly ateNereis.However, as they grew older, more birds began to specialise on mussels, especially in their second, third and fourth summers when the adults were away. At high water, most birds roosted at the mouth of the estuary or along the coast. However, several hundred fed in the fields in winter with more doing so late in the winter on warm days on Neap tides when less time was available for feeding on the estuary in daylight. Birds feeding onNereisandScrobiculariaat low water were most often seen in the fields, irrespective of age. Birds feeding onMytilusandLittorinaoccurred there rarely, but no bird eatingCerastodermawas seen there. The findings are discussed in relation to age differences in feeding skills and ability to compete successfully with other birds.
Foraging ecology of a tropical aerial feeding bird guild
Authors: WAUGH D. R. , HAILS C. J.
Published: April 2008

The feeding ecology of the constituent members of the aerial feeding bird guild was studied in Malaya. Although numbers changed with the movements of migrants, more birds were seen feeding over forested habitats than open areas. Methods of ecological isolation were seen in morphology, flight behaviour and food selection. Seasonal changes in foraging behaviour associated with breeding and migration were found in Pacific Swallows and Barn Swallows. Migrant species were observed to mix freely with residents and no evidence was found for competitive exclusion between the two groups.
Biannual breeding and moult‐breeding overlap of the Chestnut‐bellied Starling Spreo pulcher
Authors: Wilkinson Roger
Published: April 2008

At Kano, Nigeria, the Chestnut‐bellied Starling Spreo pulcher has two distinct breeding seasons, a long one from the late dry season to the early rains (February to June) and a short one in September, October and rarely November following the rains. Males have enlarged testes from February to October, so the breeding periods are probably determined by the reproductive condition of the females. Most individuals breed in both periods but some breed only in the pre‐rains period. Adult wing‐moult begins in March and April, overlapping with any breeding attempts in the latter half of the pre‐rains session; some birds continue to moult into the post‐rains session. Post‐juvenal wing‐moult is from August to January for birds reared in the previous pre‐rains period and is simultaneous with adult moult for birds reared in the post‐rains period. An increase in ambient temperature may be the most important proximate cue determining the pre‐rains and also the post‐rains breeding periods. A correlation between moult‐breeding overlap and co‐operative breeding for some tropical birds is suggested and discussed briefly.
Growth and sex of nestling Merlins in Orkney
Authors: Picozzi N.
Published: April 2008

Seventeen Merlin nestlings in six broods on Mainland Orkney in 1981 were weighed and measured regularly until they fledged. Nine chicks grew more rapidly and attained greater weights than the remaining eight irrespective of when they hatched in relation to their siblings. They also had longer beaks, hind claws, middle toes and tarsi, and thicker tarsi, and were therefore assumed to be females. It is suggested from measurements of these birds that weight in relation to wing and/or tenth (outer) primary length are sufficient to judge the sex of the young from about 13 days old. It is also suggested that the results may be generally applicable in northern Britain.
Food selection and the timing of breeding of the Blue‐and‐White Swallow Notiochelidon cyanoleuca in Venezuela
Authors: Turner Angela K.
Published: April 2008

The breeding biology of the Blue‐and‐White Swallow in Mérida, Venezuela, was studied in relation to prey availability. Breeding occurred at the end of the dry season and beginning of the wet season. The diet consisted mainly of Hymenoptera but Ephemeroptera, Coleoptera and Diptera were also important prey. Wet or cloudy weather was associated with low feeding rates at the nest and with low prey abundance. The adults spent more time gliding and used more aerial feeding stations in cloudy weather. Food abundance was highest in the wet season. Breeding thus occurs at a time when prey availability is increasing but the wet season, with its high probability of bad weather occurring, tends to be avoided.
Bowing and allopreening of captive Jackdaws Corvus monedula
Authors: Katzir Gadi
Published: April 2008

Allopreening interactions were observed in groups of captive, hand‐reared Jackdaws Corvus monedula. Head fluff and Bowing, both resembling ‘soliciting’ postures described in the literature, are described. Head fluff seems to be associated with allopreening. Bowing was performed more frequently by socially top‐ranking birds, performed and received equally frequently by females and by males, and directed at birds higher than and lower than the performer with equal frequency. Bowing was followed mostly by the recipient's moving away or by no apparent response, and only rarely by the allopreening of the actor. Allopreening was performed mostly by socially low‐ranking towards high‐ranking birds, and both when the actor was dominant to or submissive to the recipient. Bowing and allopreening seemed to be associated with situations of tension. It is suggested that Bowing here was used as intimidation rather than ‘solicitation’ or appeasement, and that allopreening and Bowing function in confirming relationships and in conveying information about relative status to other members of the group.
Lek behaviour in a parrot:the Kakapo Strigops habroptilus of New Zealand
Authors: Merton Don V. , Morris Rodney B. , Atkinson Ian A. E.
Published: April 2008

Some features of the unusual courtship behaviour of one of the world's rarest and most endangered species of bird, the flightless nocturnal Kakapo parrot of New Zealand, are described. They include excavation and maintenance by males of depressions or bowls which are grouped together and connected by tracks. Bowl systems occur in loose groups used by a number of males as traditional courtship areas and are unrelated to feeding or nesting. Bowls are used by males to emit resonant booming sounds that can be heard at distances of several kilometres, and for posturing and display in the presence of females when the latter visit for brief periods. It is concluded that absence of a permanent pair bond, the use of a mating station that is unrelated to feeding or nesting, and the temporally skewed sex ratio at the mating station in favour of males, all indicate that Kakapo are lek birds. They may be the only avian lek species to have evolved in an environment lacking mammalian predators. Further study of lek behaviour in the Kakapo may be needed if current efforts to save the species from extinction are to succeed.
Palaearctic migrants in the central Sudan
Authors: Hogg P. , Dare P. J. , Rintoul J. V.
Published: April 2008

A brief account is given of the topography and climate of the Sudan and a more detailed survey is made of the vegetation and habitats afforded to wintering Palaearctic migrants in the Sahel and Soudan savannah zones in the central Sudan. Climatic conditions during the migration seasons are mentioned and the utilization of habitats by wintering migrants is broadly surveyed.

The status of 196 Palaearctic migrant species is treated briefly. The basic observational data are tabulated to summarize observed patterns of migration in terms of date, relative abundance and region (for which purpose the central Sudan is divided into four from west to east). Hitherto unpublished field notes of the authors and their collaborators are used, together with dated observations (including specimens collected) of earlier authors, to provide the fullest data on each species.

Moreau's (1967) paradox is discussed as it relates to the Sahel and Soudan savannah zones in the central Sudan, together with the degree of competition with resident African species in those zones. Some disparities between the spring and autumn abundance and d. istribution of Palaearctic migrants are discussed in relation to 40 species ana some tentative views are advanced on the possible reasons for such disparities. Evidence is adduced which points to Lanius minor and Coraczus garrulus (and possibly Circus pygargus, partially at least) having loop migrations, south through the Sudan and north through Arabia, and Falco wespertinus south through the Sudan and north through West Africa. An explanation is offered for the greater volume of water birds observed migrating down‐Nile in spring compared with their volume up‐Nile in autumn, and for the reversed situation observed in the region west of the Nile for these same species.

Shelduck Tadorna tadorna is included in the Sudan list for the first time.
Turnover and dispersal in a Peregrine Falco peregrinus population
Authors: Mearns R. , Newton I.
Published: April 2008

In south Scotland, most Peregrines returned to the same territories to breed in successive years, though a few females changed territory from one year to the next.

Annual mortality among breeding birds was at most 9% among females (or 11% in both sexes combined). There may have been considerable annual variation, however, and excluding one exceptional year out of five reduced the estimate for females to 7%. These estimates are maxima, but are still considerably lower than those obtained from ring recoveries of dead birds reported by members of the public.

Among trapped birds, four males first bred at age two years, one at three and another at four or five; two females first bred at one year, 13 at two years old and one at three. Five other females which were seen to be in first‐year plumage but were not trapped, also laid eggs, and 12 other such paired females held territory but did not lay. Only one paired male held territory in first‐year plumage.

In their movements between natal and breeding territories, some females moved further than males, with median distances of 83 and 58 km respectively. In addition, of birds trapped breeding in the study area, a greater proportion of the males than of the females had been born locally, despite an equal sex ratio among fledglings; this was also consistent with a greater dispersal of females. In general, Peregrines made much longer movements in their first year of life than subsequently. Movements were in any direction.
Seasonal variation in the whistles of the Starling Sturnus vulgaris
Authors: Adret‐Hausberger M.
Published: April 2008

Observations of sedentary male Starlings at two sites in Brittany from December 1979 to December 1980 showed that the amount of whistled song varies during the year, principally from March to July during the reproductive season. Whistles are not numerous in summer but increase from September. These results suggest a link between whistled songs and testosterone titers. The different whistle types present different evolutions of their relative frequencies. Some are abundant during the nest building phase, others during the feeding phase. The curves were similar at the two sites for a given theme, showing that each theme constitutes an entity and that the different themes are influenced differently by environmental factors. The significance to the learning process in young birds is discussed.
Diets and feeding of Fulmars Fulmarus glacialis during the breeding season:a comparison between St Kilda and Shetland colonies
Authors: Furness Robert W. , Todd Christine M.
Published: April 2008

Diets and nest attendance of Fulmars at Foula, Shetland and St Kilda, Outer Hebrides were examined during the breeding season. At Foula, sandeels formed the bulk of the diet, with fish offal and pelagic zooplankton of minor importance. At St Kilda, 71% of regurgitates consisted of pelagic zooplankton, probably captured at night. Dietary overlap between the two colonies was 14% by species composition. Foraging trips from Foula shortly after chick hatching generally lasted for less than 10 h, while trips from St Kilda late in chick rearing often lasted more than 24 h. The diurnal pattern of feeding suggested mainly nocturnal foraging from St Kilda but both diurnal and nocturnal foraging from Foula.
The mating system of Kentish Plovers Charadrius alexandrinus
Authors: Lessells C. M.
Published: April 2008

Kentish Plover Charadrius alexandrinus pairs generally re‐nest together after the loss of a clutch. In contrast, two females who hatched clutches changed mates before re‐nesting, thus proving sequential polyandry. Observations of adults accompanying broods show that females normally desert the brood about a week after hatching. The majority of birds change mates between seasons, even if their partner from the previous season is alive.
Temperature and foraging success of Great Tits Parus major hunting for spiders
Authors: Avery Mark I. , Krebs John R.
Published: April 2008

The number of spiders caught by caged Great Tits Parus major in a 10 minute test increased in a sigmoid fashion with ambient temperature between 2 and 13°C. In control tests with immobile prey Calliphora pupae there was no significant effect of temperature. These results indicate that increasing activity of arthropod prey with temperature (Kacelnik 1979b) renders them more vulnerable to predators. We suggest that one reason why small temperate‐zone birds such as Great Tits do not forage but sing when they get up in the morning is because low ambient temperatures reduce prey activity and hence the profitability of foraging.
Does the King Vulture Sarcorhamphus papa use a sense of smell to locate food?
Authors: Houston David C.
Published: April 2008

Captive King Vultures were unable to find hidden food by smell: this species flies at high altitudes over forest, and it is suggested that they locate carcasses by watching the activities of the Cathartes vultures below them.
Winter territoriality of Mute Swans Cygnus olor
Authors: Scott D. K.
Published: April 2008

There was considerable variation in winter territoriality among Mute Swan pairs around Oxford, though most pairs maintained their territories for at least half the winter. Variation was associated with temperature and with territory quality pairs left their territories most commonly during the coldest months of the winter, and pairs on good territories, with abundant vegetation and accessible pasture. stayed longer on territory than those on poor territories with sparse vegetation and little pasture. As in other species, exclusive territorial defence was maintained at intermediate levels of resource availability, and flocks were able to settle on a few particularly good territories. Circumstantial evidence suggested that winter territories may be maintained not only to provide an adequate food supply for the owners but also to ensure access to a brerding site by preventing other individuals from taking over the area.
Moult of Malayan Barn Owls Tyto alba
Authors: Lenton Graham M.
Published: April 2008

Moult in Malayan Barn Owls Tyto alba was studied in two pairs of wild collected captive birds and from feathers taken from nest sites throughout peninsular Malaysia.

Post‐juvenile captive birds moulted nearly to completion prior to first breeding, beginning with P6 at a mean age of 301.5 days. This contrasted with the only other study of moult in captive Barn Ow‐Is in Germany when moult began at an age of 400 days, and then continued for a protracted period of two years separated by a suspension of moult during the normal breeding season.

The complex sequence of moult in primaries and secondaries both in the Malayan and German birds was similar.

Moult among adult Malayan birds in the wild showed a broad and somebyhat irregular seasonal trend With lower incidence during peak breeding periods.
Maternal nutrition, egg quality and breeding success of Scottish Ptarmigan Lagopus mutus
Authors: Moss R. , Watson A.
Published: April 2008

Samples of Ptarmigan eggs were hatched in captivity. They had been taken from ground adjacent to study areas where the wild birds' breeding success by early August, and their food plants, were measured.

Almost all deaths of chicks in captivity occurred within a few days of hatching and examination postmortem showed no specific cause. The proportion of chicks which died in captivity before 15 days of age varied markedly between years and study areas. These variations occurred in parallel with variations in breeding success in the wild populations from which the eggs had been taken. It was concluded that the survival of chicks both in captivity and in the wild was determined in part before the eggs hatched.

Variations in breeding success from year to year were correlated with the number of days that the food plants had been growing before the hens finished laying. Breeding success in the wild and chick survival in captivity were better for a ‘rich’ area overlying some base‐rich rocks than for a ‘poor’ one overlying granite and with less blaeberry. It was inferred that, as in Red Grouse, maternal nutrition affected breeding success through the quality of the eggs.
Successive nest building and polygyny of Fan‐tailed Warblers Cisticola juncidis
Authors: Ueda Keisuke
Published: April 2008

The polygynous mating system of the Fan‐tailed Warbler Cisticola juqcidis was investigated between 1978 and 1981. The male warbler builds many nests unaided; however, he has no more than one active vacant nest for courting at any time. Nest building lasted from April until August. After completing the outer fabric of a nest, the male advertised it and led a female to the nest site by a unique invitation flight. On average a male built 6.5 nests during one breeding season and three of them were accepted by females. The most successful male completed 18 nests, and mated with 11 females. Out of a total of 111 males which established a territory, 30 had no mate, 14 were monogamous, and the rest were polygynous. About 50 to 70% males were polygynous over the four years. The sex ratio varied from 1.41:1 to 2.17:1 (females: male) in the breeding population. It was partly caused by the presence of ‘floating males’. After the completion of the outer fabric of the nest, the male warbler did not take any further role in nesting and caring for young.

The polygynous mating system of the Fan‐tailed Warbler is characterized by successive nest building. Its extreme development results from the long breeding period and the male having no role in parental care.
Egg formation and the pre‐laying period of Black‐browed and Grey‐headed Albatrosses Diomedea melanophris and D. chrysostoma at Bird Island, South Georgia
Authors: ASTHEIMER L. B. , PRINCE P. A. , GRAU C. R.
Published: April 2008

Egg composition and factors influencing egg formation were studied in Black‐browed and Grey‐headed Albatrosses Diomedea melanophris and D. chrysostoma at Bird Island, South Georgia. At nests where eggs were laid, females arrived 6–7 days after males, stayed one day during which 96% of observed copulations occurred, then departed to sea for c. 16 days in D. chrysostoma, c. 10 days in D. melanophris, returning c. two days before laying. Yolk deposition, however, lasted 21 and 20 days, and started 32 and 29 days before laying, in D. chrysostoma and D. melanophris respectively. Therefore, it is probably initiated by environmental factors not by copulation. Egg, albumen and yolk mass are significantly greater in D. chrysostoma but the proportionate composition of the species' eggs is nearly identical. Reduced differences in chick mass at hatching may reflect the longer incubation period in D. chrysostoma or relate to subsequent differences in chick growth rate.
Raptor predation on wintering waders in southeast Scotland
Authors: WHITFIELD D. PHILIP
Published: April 2008

Predation on waders was investigated over the winters of 1982‐83 and 1983‐84 at a rocky shore and a small estuary in southeast Scotland. Probably all the waders which were found after being eaten were killed by raptors; mammalian predation and death due to severe weather were of minimal importance in comparison to the effects of raptor predation. Sparrowhawks were probably the major predators of waders at both sites, but owls also took some. Differences were found between the rocky shore and the estuary in the species of raptors which were seen (more Peregrines and Merlins seen on the estuary) and in the numbers of wader kills which had been plucked and eaten on open ground (more open ground pluckings, indicative of Peregrines and Merlins, found on the estuary). It is suggested that Peregrines and Merlins took more waders at the estuary due to their preference for hunting over large open expanses. Winter mortality rates due to predation varied in different species of waders: at the rocky shore the Redshank suffered the heaviest winter mortality (20% and 16%) whilst on the estuary the Ringed Plover had the highest winter mortality (19%). At both sites no large waders such as Curlews and Oystercatchers died as a result of predators and for these species other factors, such as severe weather or starvation, appeared to be a greater source of mortality. Significantly more juvenile Redshanks, Turnstones and, probably, Dunlin and Ringed Plovers were found eaten than was expected from the age‐composition of their respective populations. In the Redshank and Turnstone several differences in the behaviour of juveniles and adults were discovered which may have made juveniles more vulnerable to predation.
Natal and breeding dispersal of Canada geese Branta canadensis
Authors: LESSELLS C. M.
Published: April 2008

Natal dispersal in Canada Geese Branta canadensis breeding in the English midlands is male‐biased; males are more likely to change sites between birth and breeding, and move greater distances when they do so. Breeding dispersal is confined to within‐site movements, and the evidence for a sex bias is equivocal. It is suggested that the ability to exploit information on brood rearing areas may be an important selection pressure favouring female philopatry in wildfowl.
Brood division and transition to independence in Blackbirds Turdus merula
Authors: EDWARDS PHILLIP J.
Published: April 2008

Blackbirds Turdus merula rearing young in the Botanic Garden, Oxford, were observed over three summers (1979–81). Between 0 and 10 days after fledging the young were divided between the parents so that each fed only certain fledglings and refused to feed others. This division was temporally stable. In broods where another nesting attempt followed, the male usually took responsibility for all the young, but in final broods they were divided fairly evenly. The probability of a fledgling surviving to independence declined as the number of young a parent fed increased; thus division should be favoured. However, if the female fed some young the inter‐nest interval increased and the potential number of young that could be raised in that season was curtailed. This trade‐off is examined by means of a model. After fledging the young improved in their ability to capture prey successfully and increased the size of the prey taken. At 15–24 days after fledging, self‐feeding became more profitable than parental feeding and the young became fully independent. The timing of this transition is influenced by the parents, and it is suggested that by dividing the brood, parental feeding can be more carefully regulated so that finer control over the timing of independence is achieved.
Field tests of micropatch and prey‐size selection by Snail Kites Rostrhamus sociabilis
Authors: BOURNE GODFREY R.
Published: April 2008

Six free‐living Snail Kites Rostrhamus sociabilis were tested for preference by density for micropatches and size of apple snails Pomacea dolioides in simultaneous choice situations. Two hypotheses were tested: kites respond differentially to varying densities of larger versus smaller size classes of snails, foraging where the expected yield is greater; and kites are capable of selecting the larger size classes from a variety of available snail size classes. Kites preferred to forage in micropatches with high prey density. Variation among kites with respect to prey‐size selection was very small. In Experiments I and III there were significant inverse correlations between kite choice and snail size, but no relationship was demonstrated in the other test. Significant differences were found between mean individual weights of snails taken by kites and those not taken in Experiments I and III. No differences were observed in Experiment II. Selectivity indices show that the larger size classes were taken above their availability, although no statistical relationship existed between kite choice and snail abundance. These results corroborate the two hypotheses and suggest that kites use hierarchical decision making by employing density of snails to select appropriate feeding locations before selecting the largest individuals from those locations.
Slow continuous wing‐moult of Zebra Finches Poephila guttata from southeast Australia
Authors: ZANN RICHARD
Published: April 2008

Moult of the remiges was studied over eight years in a population of Zebra Finches from southeast Australia. In first‐year birds the first primary was lost at mean age of 80 days in both sexes; moult took 204 days to complete in males and 223 in females. Birds hatched in autumn postponed the start of their primary moult until spring. Primaries were replaced slowly in a rigid, non‐overlapping, ascending order from #1 to #9 but the secondaries did not display a rigid sequence.

Adult Zebra Finches moulted remiges throughout the year. Primary moult was initiated in any month. Primary moult had a mean duration of 229 days for males and 240 days for females. Primaries moulted in continuous waves: the interval between successive moults in males was –16 days and +6 days in females. Limited food, low temperatures and breeding slowed, but did not stop, wing‐moult. Birds caring for eggs and young actively replaced remiges.

The pattern of wing‐moult displayed here by Zebra Finches is exceptional for passerines and may be related to the opportunistic breeding strategy necessary in an arid, unpredictable environment. Its presence in the Victorian birds may be non‐adaptive.
Origins, phytogeny and taxonomy of the gadfly petrels Pterodroma spp
Authors: IMBER M. J.
Published: April 2008

Taxonomic characters of gadfly petrels (Procellariidae: Pterodroma spp.) are reviewed and the genus is redefined. The structure of the upper intestines, which have become helicoidally twisted to varying degrees in most species, is an important character not hitherto used. Results of a phylogenetic study of the genus based mainly on the development of helicoidal intestines agree substantially with findings from studies of the Mallophaga parasitizing these petrels. One species, the Kerguelen Petrel Lugensa brevirostris, previously classified in Pterodroma, is shown to have closer affinity with some fulmar genera. The Tahiti Petrel Pseudobulweria rostrata and its rare or extinct relatives, formerly placed in a superspecies of Pterodroma, are more closely related to the Procellaria and Bulweria petrels, and may be derived from the link between the subfamilies Procellariinae and Fulmarinae. From consideration of the fossil record, anatomical characters and Mallophaga, a phylogeny of the Procellariidae is proposed which supports its monophyletic origin. Gadfly petrels apparently descended from the fulmars through the ancestral lines of Snow Petrels Pagodroma, the Kerguelen Petrel and finally the Blue Petrel Halobaena, which may have given rise separately both to gadfly petrels and to the prions Pachyptila. A late Pliocene origin of Pterodroma in the vicinity of southern New Zealand is possible. The genus Pterodroma is divided into four subgenera, representing four connected radiations, and 29 species are recognised. In probable chronological order, Proaestrelata (new subgenus) contains five species and is restricted to the Pacific Ocean, Cookilaria comprises six species restricted as breeders to the South Pacific, Hallstroma has seven species mainly in the tropics of the Pacific, Indian and South Atlantic Oceans, whereas Pterodroma includes 11 species which extend as breeders from the southwest Pacific west to the South Atlantic and into the North Atlantic. Ecological, physical and physiological adaptations in the evolution of gadfly petrels are discussed.
Notes on the effects of E1 Niño on the seabirds of the Mollendo district, southwest Peru, in 1983
Authors: HUGHES R. A.
Published: April 2008

In the austral summer of 1982–83 the cool Peru Coastal Current Zone of the Pacific Coast of South America was affected by the strongest and most prolonged incursion of the warm El Niño Current in at least 58 years. An account is given of the visual effects of the disturbance on the seabirds of the Mollendo district on the coast of southwest Peru. With one exception, local numbers of the endemic cool water species were drastically reduced, with little evidence of recovery up to April 1984. During the period when El Niño was at its height, several warm water species of seabirds, previously either virtually or completely unknown at Mollendo, were recorded.
The displays of the White‐throated Manakin Corapipo gutturalis in Suriname
Authors: PRUM RICHARD OWEN
Published: April 2008

The courtship displays of the White‐throated Manakin Corapipo gutturalis (Pipridae) were observed in the Brownsberg Nature Preserve, Suriname, for over 50 h on 17 days between 17 October and 17 December 1982, and the display elements and calls are described. Males perform displays from perches in trees, in flight and on mossy fallen logs. The perch displays are performed as preliminaries to the log‐approach displays which are given while in flight towards the log. The log‐approach displays vary in length and complexity from a short flight from a nearby perch down to the log, to a dramatic flight above the canopy and back to the log. As males land, they perform a series of aerial manoeuvres and give a complex vocal and mechanical display call. Males may also perform a slower silent moth‐flight log approach. The log displays are the culminating elements of courtship and copulation is known to take place there (Davis, T.A.W. 1949. Ibis 91: 146–147). All the courtship displays can be performed either solitarily by a single male or by a group of up to seven males which compete simultaneously for access to single display sites at a series of different logs. Fourteen display logs were located dispersed in two areas 250 m wide which were separated by 350 m, but it was not determined whether these areas constituted separate leks with different pools of possible mates. The behaviour of C. gutturalis is compared with that of the White‐ruffed Manakin Corapipo leucorrhoa and other manakins. Male Corapipo appear to have abandoned defence of exclusive advertisement territories in favour of simultaneous competition for a series of different display sites. This detached or mobile form of lek is unique among known manakins and a mechanism for its evolution through female choice is discussed.
The use of radio‐tracking for monitoring Great Tit Parus major behaviour: a pilot study
Authors: EAST M. L. , HOFER H.
Published: April 2008

Data obtained from a pilot radio‐tracking study of Great Tits are presented. Three males were tracked intensively in sequence between January and April with varying efficiency. Radio‐tracking provided useful information on range size and spatial patterns of range use. It also facilitated behavioural observations and the construction of time budgets. If the use of radio signals is a reliable means of predicting behaviour, the data presented from this study indicate that standard observation may be highly biased.
The scapulocoracoid of flightless birds: a primitive avian character similar to that of theropods
Authors: FEDUCCIA ALAN
Published: April 2008

The scapula and coracoid of the first bird Archaeopteryx represents a highly specialized morphology approaching that of modern carinate birds, with the scapula meeting the coracoid at an angle of approximately 90o. The primitive condition of the avian scapula and coracoid is exhibited by the flightless ratites, birds exhibiting many other primitive characters of the skeleton, either retained from primitive ancestors or derived through neoteny. The fact that the scapulocoracoid of ratites is the primitive condition is confirmed by its presence in the embryos of certain birds, and its presence through neoteny in other unrelated birds that have secondarily evolved Sightlessness. This morphology of the primitive avian scapulocoracoid closely approaches that of theropod dinosaurs, such as Deinonychits, and may well indicate relationship between the two groups.
Mating systems among European passerines: a review
Authors: MØLLER ANDERS PAPE
Published: April 2008

A review of the mating systems of 122 relatively well‐studied European passerines (out of 172 species) is given. Of all species, 39% are polygynous and 25 of the 47 polygynous species are regular polygynists exceeding the limit of 5% polygyny in a population. Of 46 polygynous species, 63% are monoterritorial (having a maximum of one territory), the rest being polyterritorial (having a maximum of more than one territory). Regular polygyny is more common among polyterritorial passerines. Polygyny is frequently found among species breeding in open habitats (marshes, meadows, pastures and low shrubs). Polyterritorial species tend to have tropical winter quarters more frequently than monoterritorial species do. Colonial breeding is absent from the polyterritorial group. Monogamous male passerines participate more frequently in feeding nestlings than their polygynous counterparts do. Regular polygynists tend to be sexually dimorphic in plumage more often than infrequent polygynous passerines, and polyterritorial passerines similarly tend to be plumage dimorphic more often than monoterritorial species. Sexual size dimorphism was more pronounced in monoterritorial than in polyterritorial passerines.
Reproductive success and survivorship of the Galapagos Hawk Buteo galapagoensis: potential costs and benefits of cooperative polyandry
Authors: FAABORG JOHN
Published: April 2008

The Galapagos Hawk Buteo galapagoensis is one of few species showing cooperative polyandry. As many as four males may mate with one female and share a territory and nest, Such groups, on average, produce more young than monogamous pairs, but on a per male basis (assuming that each male of a group has an equal chance to fertilize each young) polyandrous males produce fewer young per year than monogamous males. Territorial breeding birds show higher yearly survivorship (90%) than non‐territorial, non‐breeding birds (50% or less). All territorial birds seem to remain on their territories for life, and monogamous pairs actually constitute the remnants of polyandrous groups. Some potential factors producing such an unusual system are discussed. Limited breeding space and high mortality among non‐territorial birds seem to work in favour of group breeding in this and other cooperative species. Polyandry may be favoured because of the reduced value of extra females in hawk breeding behaviour. Equal‐status males may occur because of the lack of kinship among cooperating males and the high potential genetic cost of being a helper in a long‐lived, low fecundity species. Other possible factors favouring group breeding are territory acquisition and the variable nature of the Galapagos climate.
Phylogenetic relationships of turacos (Musophagidae; Cuculiformes) based on comparative chromosome banding analysis
Authors: TUINEN P. VAN , VALENTINE M.
Published: April 2008

Cladistic analysis of chromosome banding patterns in nine species of turacos (Musophagidae; Cuculiformes) revealed the existence of two clades, one comprised of species of the genera Tauraco, Gallirex (=Tauraco) and Musophaga, and another of species of Corythaixoides. The results are consistent with the allocation of the former to a subfamily Tauracinae and the allocation of the latter to the subfamily Criniferinae which also includes Crinifer. Comparative C‐banding suggests that the putatively polytypic Tauraco corythaix is occupied by more than one species; more such studies in this group may resolve other questionable cases of conspecificity. Comparison of our results to studies of Cuculidae suggest that they do not share with musophagids two major derived fissions that set musophagids apart from other avian orders. Detailed comparison of ancestral karyotypes from several groups (Galliformes, Cuculidae, Musophagidae and Opisthocomidae) may help to resolve their still unresolved phylogenetic relationships.

Our results confirm previous studies showing karyotypic uniformity within avian orders. The uniformity suggests a negligible role for chromosome rearrangement in speciation in this group, since several indisputably distinct species do not differ karyotypically in any significant fashion. Intraspecific uniformity is punctuated by the presence in Livingstone's turaco Tauraco corythaix livingstonii of inversion heteromorphism, the class of rearrangement encountered most frequently in other avian species.
The diet of Emperor Penguins Aptenodytes forsteri in Adelie Land, Antarctica
Authors: OFFREDO CHRISTOPHE , RIDOUX VINCENT
Published: April 2008

This first quantitative study of the diet of Emperor penguins is based on 29 stomach contents collected with a water off‐loading method in Adelie Land. The Emperor is largely ichthyophagous (65% by number and 95% by weight) and feeds extensively on small nototheniids (97% of the fish are 40–125 mm in overall length). These results and data on meal size and feeding frequency of the chick suggest that Emperors are off‐shore foraging birds offering little competition for food with other sea‐birds or mammals.
Age differences in the feeding ability of Moorhens Gallinula chloropus
Authors: SUTHERLAND WILLIAM J. , JONES DAVID W. F. , HADFIELD ROBERT W.
Published: April 2008

Numerous studies have shown that juvenile birds obtain food at a slower rate than do adults (Norton‐Griffiths 1968, Recher & Recher 1969, Orians 1969, Dunn 1972, Davies& Green 1976, Groves 1978), We compared the foraging behaviour of adult and juvenile Moorhens Gallinula chloropus and tried to assess the relative importance of different components of feeding in determining the intake rate.
Breeding synchrony of Cory's Shearwater Calonectris diomedea on Selvagem Grande
Authors: JONES MARTIN J.
Published: April 2008

Breeding synchrony of Cory's Shearwater was assessed by comparing the tarsus‐lengths of neighbouring chicks. Chicks were closer in size when they were less than 3 m apart than when they were 30 or 60 m apart. Nearest neighbours were more highly synchronized to each other than they were to their second or third nearest neighbours. It is suggested that where nests are widely spaced, shearwaters may synchronize very closely with their nearest neighbour. Where nesting is dense, an average synchrony, with a number of pairs, may be attempted. A likely advantage of synchronous breeding is a reduction in predation by gulls.
Factors determining the laying date of the Waved Albatross Diomedea irrorata
Authors: RECHTEN C.
Published: April 2008

The Waved Albatross laying period is between mid‐April and the end of June. This paper investigates the factors determining when, during this period, a female lays. It is shown that birds breeding for the first time lay relatively late. For older birds, the laying date depends on date and outcome of the previous year's attempt: females that bred successfully in the previous year lay slightly later than in that year, while birds that failed lay earlier. A corresponding difference exists in the dates of arrival at the breeding grounds of successful and failed males. It is argued that one calendar year is not quite sufficient for pairs that have reared a chick successfully to regain breeding condition, while failed breeders can choose the laying date more freely.

Under catastrophic El Niño weather conditions in 1983, all albatrosses arrived late at the breeding grounds, but still the birds that had failed in 1982 were clearly earlier than those that had reared a chick.