bluuebunny/crossref_metadata_2025 huggingface dataset:
The social organization of the Scarlet Robin Petroica multicolor and Flame Robin P. phoenicea in southeastern Australia: a comparison between sedentary and migratory flycatchers
Authors: ROBINSON DOUG
Published: April 2008

Scarlet Robins Petroica multicolor and Flame Robins P. phoenicea occurred sympatrically during the breeding season in southeastern Australia. Scarlet Robins that occur territories in forest habitat remained there throughout the year, while those, mostly first‐year birds, that occupied territories in grassland habitat were present only during the non‐breeding season. Flame Robins were present for 9 months of the year and were territorial for 6 of those months. The migratory Flame Robin did not show more intense or prolonged territorial or courtship behaviour than the sedentary Scarlet Robin, despite having to obtain territories and mates when it returned each year. It is suggested that the similarities between the two species' social organizations arise partly from high adult survivorship (70–75%) and lengthy breeding seasons (4–5 months). High adult survivorship and scarcity of suitable breeding habitat also caused intense competition for territories and mates, and appears to have led to the evolution of bright, signalling plumages among female and young male Scarlet Robins. Scarcity of females and breeding habitat may have caused delayed maturation of plumage among male Flame Robins.
A global review of island endemic birds
Authors: JOHNSON T. H. , STATTERSFIELD A. J.
Published: April 2008

Although fewer than one‐fifth of the world's bird species are restricted to islands, over 90% of bird extinctions during historic times have occurred on islands. The major identified cause has been the effects of exotic animal species introduced by man; the largest number of documented extinctions has occurred on islands of the Pacific Ocean.

Some 39% (402) of threatened bird species are restricted to islands and more than 907; of these are endemic to a single geopolitical unit. The largest numbers occurring in such units are in Indonesia (91) and the Philippines (34). As a region, the Pacific holds more threatened species (110) than any other, including almost half of those considered Endangered and over 40% of the Vulnerable species.

Most threatened island species are forest‐dwelling. A high proportion of the Endangered species use seasonal/temperate forest. While habitat destruction now poses the greatest overall threat to island birds (affecting over half the species restricted to islands), the presence of introduced species threatens 30 of the 66 Endangered species.

Although immediate extinctions of island species can best be averted by mitigating the effects of introductions, the removal of native forests will be a more severe problem in the longer term. There is an urgent need for ecologists to provide detailed information on the habitats of both threatened and endemic species so that more appropriate and effective conservation programmes can be developed.
Breeding systems of New Zealand Snipe Coenocorypha aucklandica and Chatham Island Snipe C. pusilla; are they food limited?
Authors: MISKELLY COLIN NI.
Published: April 2008

New Zealand Snipe Coenocorypha aucklandica were studied over six breeding seasons on the Snares Islands. The study area (7.5 ha) held about 20 pairs at a density of 3.2 ± O.5 pairs/ha, plus 5 to 25 nonterritorial birds. Most matings were monogamous but simultaneous polygyny was recorded in one territory (by two different males) in four consecutive seasons. Males courtship fed females before egg‐laying. The typical clutch was two eggs, laid three days apart. Incubation was shared equally by the sexes in monogamous pairs and took 22 days. Some females with polygynous mates attempted to incubate unaided, which took about 38 days. Broods were split at hatching, with the male caring for the first chick to leave the nest. Chicks were fed by adults for at least 41 days, and did not become independent until about 65 days old. Growth rates were slow compared to Common Snipe Gallinago gallinago and full plumage took about 54 days to attain. No pairs were double‐brooded but 43% of pairs that failed during incubation or early chick‐rearing renested together. Some breeders of both sexes who had lost their dependent chick bred a second time with a new mate while their first mate continued rearing the surviving chick (sequential polygyny and polyandry). Hatching success was 80%, and fledging success was 48%. Each pair produced, on average, O.6 fledglings per year.

Chatham Island Snipe C. pusilla were studied on Rangatira Island during the 1983–84 breeding season. Breeding density was about 5.6 pairs/ha. The breeding system was very similar to that for C. aucklandica but chicks became independent at about 41 days old. Hatching success was 89%.

Compared to Common Snipe, Coenocorypha snipes occurred at high densities, had courtship feeding, large eggs, a long interegy interval, a small clutch, shared incubation and a long incubation period. Nest desertion rates were high, but overall hatching success was also high, chick growth rates were slow, there was a long period of chick dependence and a long relaying interval following nest failure or chick loss. Survival rates of both adults and chicks were high. These differences are attributed to the absence of predation, and to intense intraspecific competition for food in a stable environment.
Interspecific patterns of seed selection among granivorous passerines: effects of seed size, seed nutritive value and bird morphology
Authors: DIAZ MARIO
Published: April 2008

The relationships between seed characteristics (size and nutrient contents) and bird morphology were investigated in ten species belonging to three specialized families of granivorous passerines. Wild‐caught birds were exposed in captivity to a fixed mixture of thirteen seed types before measuring their consumption rates and seed preferences. A multivariate analysis of seed characteristics showed two principal and independent gradients of covariation, namely seed nutritive value and seed size. The smaller the birds, the more nutritive the seeds they selected, this result being largely independent of the family the bird belonged to. The selected seed size was directly related to both the body and bill sizes of the birds, hut these relationships varied between families, most probably as a consequence of interfamilial differences in the structure of the ramphotheca and the associated seed handling method.
The breeding behaviour of the KnotCalidris canutus
Authors: WHITFIELD D. PHILIP , BRADE JEREMY J.
Published: April 2008

This paper presents descriptions of the behaviour of KnotCalidris canutusbreeding in high arctic Canada. Knot nested within territories which were of little importance as a food source. Males defended territories by singing from the ground, aerial chases, threat displays (horizontal point), fighting, and low flights in which the wings were held vertically over the back (V‐wing flights).

Songflights performed by males seemed to serve a mate‐attraction function. The commonest heterosexual display was a tail‐up display, used mainly by males prior to clutch completion. Males also used a nest scrape display and a ground point display in advertising potential nest sites to females. Behaviour preceding copulation was variable but usually included tail‐up displays and the male pecking the back of the female.

Anti‐predator behaviour when on the nest involved remaining still until a predator was very close, whereupon distraction displays were used. Both sexes incubated but only males cared for chicks. Caring for chicks involved leading chicks to favourable feeding areas, brooding and vigilance, distraction displays, and harrassment or physical attack of avian predators.

The displays used by breeding Knot tend to be unlike those of most congenerics and suggest that the Knot is a rather peripheral member ofCalidris.
An improved technique for estimating pectoral muscle protein condition from body measurements of live gulls
Authors: BOLTON M. , MONAGHAN P. , HOUSTON D. C.
Published: April 2008

Body measurements, which could be taken from live birds, were used to estimate total pectoral muscle protein in Lesser Black‐backed Gulls Larus fuscus. The maximum cross‐sectional area of the flight muscles was measured from the profile of the muscle surface over the keel, and this was used in conjunction with the length of the flight muscle to estimate muscle volume. The estimate of muscle volume was then used with fresh body weight to estimate total flight muscle protein. A highly significant correlation was found between the estimated values and actual pectoral muscle protein mass determined by carcass analysis. The model developed from the source group was then validated using a second independent sample, in which flight muscle protein was estimated from the model. Carcass analysis again demonstrated a good correlation between estimated and actual total protein. Different methods of controlling for body‐size to calculate protein condition from measures of total protein were considered. The technique described here provides a simple and reliable method of estimating pectoral muscle protein condition in live gulls which could be applied to studies of body condition in other species.
Six captures of a dark‐rumped, fork‐tailed storm‐petrel in the northeastern Atlantic
Authors: BRETAGNOLLE V. , CARRUTHERS M. , CUBITT M. , BIORET F. , CUILLANDRE J.‐P.
Published: April 2008

We report here the occurrence of at least six records since 1983 of dark‐rumped and fork‐tailed Storm‐petrels. The first one was attributed to the Swinhoe's Storm‐petrel Oceanodroma monorhis, a subspecies or a close relative of Leach's Storm‐petrel O. leucorhoa, breeding in Japan. As it seemed unlikely that six birds from Japan would appear in the northeastern Atlantic nearly simultaneously, a closer examination of measurements and calls was performed. However, after a careful study of systematics within the Leach's Storm‐petrel complex, it is concluded that the European birds are inseparable from monorhis, and it is suggested that a yet undiscovered colony may exist in the North Atlantic.
Intraspecific nest parasitism in Starlings Sturnus vulgaris: effects of disturbance on laying females
Authors: FEARE C. J.
Published: April 2008

Female Starlings Sturnus vulgaris that laid distinctive eggs at Worplesdon, Surrey, in 1988 and 1989 were made to desert their partially completed first clutches by removing their eggs part way through the laying sequence. Most of these Starlings continued to lay, but in other Starlings' nests, and most of them subsequently laid a replacement clutch that they reared themselves. Using estimates of the success of nests in the colony over 14 breeding seasons, it is concluded that intraspecific nest parasitism offers a means of maximizing annual chick production in the event of disturbance causing the loss of first‐clutch eggs.
Mortality causes in British Barn Owls Tyto alba, with a discussion of aldrin‐dieldrin poisoning
Authors: NEWTON I. , WYLLIE I. , ASHER A.
Published: April 2008

During 1963‐89, 627 Barn Owl Tyto alba carcasses were received for autopsy and chemical analysis. Much larger numbers were received per month outside the breeding season than within it, with peaks in autumn (mainly juveniles) and late winter (adults and juveniles).

The main causes of recorded deaths were collisions (mostly with road traffic) and starvation. No great seasonal variation occurred in the main causes of recorded deaths and starved juveniles were reported even in summer. Most starved males weighed less than 240 g, and most starved females less than 250 g.

Another important cause of mortality in eastern arable counties, at least to 1977, was poisoning by organochlorine pesticides, especially aldrin/dieldrin. Levels of HEOD (the metabolized product of aldrin/dieldrin) in the livers of birds that had apparently died of aldrin/ dieldrin poisoning were in the range 6–44 ppm (geometric mean 14 ppm). Pesticide victims formed up to 40% of all dead Barn Owls obtained from some eastern counties during 1963‐77. By 1987‐89, HEOD levels in Barn Owls in eastern counties had fallen to less than 1.6 ppm, and no deaths from organochlorine poisoning were recorded.

Organochlorine pesticides almost certainly contributed to population decline in eastern England evident in the 1950s and 1960s, and reductions in the use of these chemicals may have allowed a subsequent increase, apparent over the last 10–15 years.
Nest construction and egg‐laying in Edible‐nest Swiftlets Aerodramus spp. and the implications for harvesting
Authors: KANG N. , HAILS C. J. , SIGURDSSON J. B.
Published: April 2008

The influence of nest harvesting upon nest construction and egg‐laying was studied in the White‐nest Swiftlet Aerodramus fuciphagus and the Black‐nest Swiftlet A. maximus in Singapore. A study of nestling energetics allowed an estimate to be made of adult foraging abilities. The energy and nutrients required for nest construction are easily acquired by foraging but the females may face a shortage of energy or depletion of stored lipids during egg formation. Removal of nests did not affect the size or quality of replacement nests or clutches, but may aggravate the lipid shortage. Nest removal did reduce breeding success in replacement nests and, in the White‐nest Swiftlet, disturbance to the colony resulted in an increased laying interval between first and second eggs. Our results indicated that commercially exploited colonies should be left unharvested for the middle part of the breeding season to allow a period of successful reproduction.
Habitat variation and population regulation in Sparrowhawks
Authors: NEWTON I.
Published: April 2008

In a study area in south Scotland, Sparrowhawks did not occupy the available nesting places at random, but more often used those places where breeding success was highest (here called high‐grade places). Most birds stayed on particular nesting places for only one year, but others stayed up to 8 years. Some birds moved from low‐ to high‐grade places as they aged. Continued occupancy of certain places was thus produced by many different individuals occupying such places in rapid succession, but most staying for only one breeding season.

On the most used (high‐grade) nesting places pairs produced more than enough young per breeding attempt to offset the average annual mortality, but on the less used (low‐grade) places they produced too few. Low‐grade nesting places therefore acted as a sink, whose occupancy could be maintained only by continual immigration. Over the study area as a whole, the population was in balance, with reproduction matching mortality.

Habitat changed over periods of 15–30 years, as woodland matured. Nesting places in young woods, with small densely‐growing trees, showed the highest occupancy and nest success. Both aspects of performance declined as the woodland aged, and trees became larger and more widely spaced. Long‐term stability in nest numbers and success in the study area as a whole was associated with a system of rotational forest management, which ensured a continuing availability of young woods.

It is proposed that spatial variation in habitat quality is involved in the regulation of breeding numbers. Removal experiments confirmed the presence of non‐breeders, which could attempt to breed when high‐grade nesting habitat was made available to them, but otherwise remained as non‐breeders despite the presence of vacant low‐grade habitat. This situation, involving an interaction between habitat quality and bird quality, probably occurs in some other raptors too.
Extensive monitoring programmes viewed as long‐term population studies: the case of North American waterfowl
Authors: NICHOLS JAMES D.
Published: April 2008

Several long‐running and geographically extensive survey programmes provide information used to make annual management decisions for North American waterfowl populations. Data from these programmes can also be viewed as resulting from long‐term population studies and have formed the basis for a number of retrospective analyses. Short‐term studies have been used to investigate mechanisms underlying results of the retrospective analyses. Results of the long‐term and short‐term studies complement each other nicely and have led to many useful inferences about North American waterfowl population dynamics. However, important questions remain unanswered, and it is suggested that many of these could best be addressed using an experimental approach.
Broad‐scale patterns in geographical and habitat distribution of migrant and resident passerines in Britain and Ireland
Authors: FULLER R.J. , CRICK H.Q.P.
Published: April 2008

We analysed patterns of breeding habitat use in migrant and resident passerines on a broad geographical scale in Britain. Migrants were less widely distributed than residents and used fewer habitats. Although resident genera that were more widespread used more nesting habitats, this did not hold for migrant genera though it did at the species level. Although migrancy status in Europe has been associated with the use of ‘open’ structural habitat types (e.g. scrubland), evidence from Britain was contradictory. Within lowland woodlands the ratio of migrants to residents and the density of migrants was highest in habitats with large areas of young growth. The highest migrant ratios of all, however, were recorded in mature upland woods, with little or no undergrowth. These upland woods carried the lowest densities of residents. Regression models accounting for variation in the migrant ratios and densities in woodland habitats varied according to the geographical scale on which they were constructed. The extent of young growth was a strong predictor of migrant ratios and densities in south‐east England but not for woods in the north and west. Resident densities in northern and western woods were inversely related to altitude.
Flight‐range estimates for small trans‐Sahara migrants
Authors: BIEBACH HERBERT
Published: April 2008

Arguments in support of the non‐stop and the intermittent strategies for crossing the Sahara have been based on data on the fat reserves of birds before the crossing and of birds grounded in the desert. In this paper, flight‐range estimates were calculated and the necessary assumptions about air speed, energy input during flight, and energy equivalent of body reserves were evaluated. As examples, Willow Warblers Phylloscopus trochilus and Garden Warblers Sylvia borin were investigated during autumn migration from two study sites north of the Sahara and two study sites in the desert. In still air, the flight‐range for both species at all study sites was too short to reach the Sahel zone without refuelling. It is concluded that birds depend on tailwinds for a successful crossing, independent of a non‐stop or an intermittent migratory strategy, and that weather conditions in autumn allow them to rely on tailwinds.
Yellow Wagtail Motacilla flava migration from West Africa to Europe: pointers towards a conservation strategy for migrants on passage
Authors: WOOD BRIAN
Published: April 2008

The biology of one passerine migrant, the Yellow WagtailMotacilla flava,is examined in order to identify factors which need to be considered when attempting to conserve migrants on passage. The distribution of Yellow Wagtails in West Africa, prior to northward (spring) migration, is affected by food supplies and by different racial and sexual responses to environmental factors. Consequently, each breeding population relies on a wide range of sites, but those occupied towards the end of the dry season and ones used as stepping‐off points for migration may be particularly vital.

Energetic considerations point towards a non‐stop trans‐Saharan flight being used rather than a series of short flights with resting stops in the desert. However, adverse conditions during migration could make stop‐overs unavoidable. The most direct routes between wintering and breeding areas are preferred, and the initial desert crossing is accomplished at a faster pace than later stages of the journey.

Yellow Wagtails emigrate from West Africa in a sequence related to the onset of spring on their breeding sites, rather than in response to rainfall in Africa: moult, fattening and emigration are probably endogenously controlled. However, competition from African resident birds may also be an important factor affecting the timing of migration.

Races breeding in southern Europe are most likely to be adversely affected by degradation of the Sahel. Empirical evidence suggests that conditions on the wintering grounds are more likely to regulate population size than conditions experienced on migration, but more detailed studies are needed in Africa before sound conservation strategies can be designed.
Conservation of migrants on their wintering grounds: an overview
Authors: KELSEY M.G.
Published: April 2008

Most research on the behaviour and ecology of wintering migrants has been undertaken in the Neotropics. In Africa, conservation biologists are faced with a comparative paucity of baseline data to assess the significance of environmental change, in contrast to the comparatively well‐developed monitoring programmes in place on the breeding grounds. A programme of monitoring, established through international collaboration and matched with further ecological research, is required. Given the ‘dispersed’ distribution of most passerine migrants, determination of the significance of apparent detrimental effects can be hard to ascertain. However, migrants may provide conservationists with an effective vehicle for the provision of input into region‐wide development policy. It is only through influencing regional development policies within the continent that large‐scale and long‐term conservation of important bird habitats will be achieved.
The diet of the Sea Eagle Haliaeetus albicilla and Golden Eagle Aquila chrysaetos in western Scotland
Authors: WATSON J. , LEITCH A. F. , BROAD R. A.
Published: April 2008

The diets of Sea Eagles Haliaeetus albicilla and Golden Eagles Aquila chrysaetos living sympatrically in western Scotland were studied using pellets and prey remains collected at roosts and nest sites throughout the year. Both species showed changes in diet between winter and summer, and there were differences between species in both seasons. As a rule, Sea Eagles took proportionately more seabirds, waterfowl (ducks and waders) and fish, whilst Golden Eagles took proportionately more rabbits and hares. Sea Eagles had a broader diet than Golden Eagles but a measure of dietary overlap based on taxonomic composition indicated an overlap of more than 90% between the two species.
Nesting biology of the Short‐tailed Paradigalla Paradigalla brevicauda
Authors: FRITH CLIFFORD B. , FRITH DAWN W.
Published: April 2008

Six nesting attempts of a ringed Short‐tailed Paradigalla Paradigalla brevicauda between September 1986 and February 1989 in Papua New Guinea are reported. Nests are described and one illustrated. Previously undescribed eggs, of two single‐egg clutches from the same female, lack broad longitudinal streaks typical of most Paradisaeinae eggs. The hatchling is naked, dark‐skinned, with fully formed facial wattles. Fifty seven hours of observation at one nest confirmed single parent attendance. Of 66 identified nestling meals 65% were animal, including frogs and skinks, the remainder fruit. Growth and development of a nestling, that fledged at 26 days old, are described. Another young was fed by its parent 108 days after leaving the nest. Breeding and feeding of P. brevicauda are reviewed. The presumed female studied attended six nests within 100 m2 over 29 months. Uniparental nesting suggests males are promiscuous, which is discussed with respect to proposed Paradigalla hybrids.
Early settling the following spring: a long‐term benefit of mate desertion by male Great Reed Warblers Acrocephalus arundinaceus
Authors: URANO EIICHIRO
Published: April 2008

In a population of the Great Reed Warbler Acrocephalus arundinaceus in central Japan 33 cases of mate desertion by males were recorded during eight breeding seasons. Thirty of these occurred at the end of the breeding season. The absence of the male parent during the nestling period affected neither the frequency of nestling starvation nor the return of females. Eight deserters were confirmed to have begun moulting prior to the fledging of their young. Males which had abandoned their territory relatively early in the summer tended to settle earlier and to be polygynous the following spring. As earlier settling is an important factor influencing polygyny in males, an increased chance of early settling the following season can be regarded as a long‐term benefit of mate desertion.
The post‐fledging survival of young Guillemots Uria aalge in relation to hatching date and growth
Authors: HARRIS M. P. , HALLEY D. J. , WANLESS S.
Published: April 2008

The post‐fledging survival of a total of 1277 young Guillemots Uria aalge ringed in 6 years was assessed using sightings of 267 individuals back at the natal colony and recoveries of 46 ringed birds. In two years there was a significant decline in survival prospects with estimated hatching date, the first time such a trend has been demonstrated in the Alcidae. In these years pairs breeding early had a 2–3 times greater chance of having a young survive to return to the colony than pairs breeding three weeks later. Hatching date had no effect on survival prospects in the other four seasons and in none of the years did chick body condition have a demonstrable effect on post‐fledging survival.
The survival rate of Australian passerines
Authors: YOM‐TOV YORAM , McCLEERY ROBIN , PURCHASE DAVID
Published: April 2008

The Australian avifauna is composed largely of two groups–the ‘old endemics’, species that originated in Gondwana and radiated in Australia and New Guinea, and the ‘new invaders’, species that originated in Asia and invaded Australia during the Pleistocene. In addition, several species were introduced by Europeans during the last 200 years. The old endemics have clutch‐sizes significantly smaller than those of the new invaders (Yom‐Tov 1987). The aim of this paper was to study the survival rates of Australian passerines from the three groups.

The survival rates of 3 5 species of Australian passerines were calculated by using recapture data provided by the Australian Bird Banding Scheme for birds older than one year. Survival depends primarily on body‐mass, with no difference between the old endemics and the new invaders. It is suggested that the survival rates of birds younger than one year is different between the two main groups.

Overall, the survival rates of Australian passerines is at least 1.2 greater than that of equal‐sized British passerines. The survival rates of the introduced House SparrowPasser domesticusand BlackbirdTurdus merulawere similar on the two continents, suggesting either that insufficient time had elapsed since their introduction to Australia for them to adapt to local conditions, or that the habitats occupied in Australia were so modified by human activities that selection did not favour long lives. The survival rate of the introduced StarlingSturnus vulgariswas lower in Australia, probably because it lives in natural habitats there.
Reversal of breeding season by lowland birds at higher altitudes in western Cameroon
Authors: TYE HILARY
Published: April 2008

Evidence of breeding during the dry season is given for 31 species of lowland birds in montane and semi‐montane areas in western Cameroon. At least 17 of these species are shown to breed in the wet season at lower altitudes in West Africa. This reversal of breeding season may be due to the unusually heavy rainfall and high humidities which cause temperatures to decrease more rapidly with altitude than on mountains with drier climates. Low temperatures and heavy rainfall during the wet season prevent almost all montane species from breeding then, and affect similarly the lowland birds whose ranges overlap with those of montane birds. Breeding seasons of some lowland species in Cameroon have previously been considered prolonged, but separation of breeding records by altitude reveals clear seasonality.
Lead poisoning in wild populations of Marsh Harriers Circus aeruginosus in the Camargue and Charente‐Maritime, France
Authors: PAIN D. J. , AMIARD‐TRIQUET C. , BAVOUX C. , BURNELEAU G. , EON L. , NICOLAU‐GUILLAUMET P.
Published: April 2008

Lead poisoning of waterfowl, through the ingestion of spent gunshot, has been recognized as a mortality factor for over a century. However, in Europe relatively little attention has been paid to raptors that may ingest shot embedded in the flesh of prey. The present study examines the incidence of lead poisoning in wild Marsh Harriers Circus aeruginosus trapped at two sites in France, the Camargue and Charente‐Maritime.

Eight captive Marsh Harriers (controls) had blood lead (PbB) concentrations of 5.3–10.8 μg per dl. Of 94 wild birds trapped during the winters of 1990/1991 and 1991/1992 either in baited clap traps or in mist nets at night roosts, 29 (31%) had elevated (>30 μg/dl) PbB concentrations and 13 (14%) had concentrations indicative of clinical poisoning (> 60 μg/dl). Similar percentages of birds caught using the two trapping methods had elevated (>30 μg/dl) PbB concentrations. However, clap netting appeared to select for more heavily contaminated birds and for juvenile birds, although the two are not necessarily correlated. In the Camargue, significantly more females than males trapped in clap nets had elevated PbB concentrations.

The incidence of shot in regurgitated Marsh Harrier pellets increased significantly between October and December, indicating increased exposure to lead as the hunting season progressed. There appeared to be a parallel increase in PbB concentrations throughout the hunting season, although this could not be clearly demonstrated as sex ratios were different during different sampling periods.

Elevated PbB concentrations of harriers in the Camargue are likely to result primarily from the ingestion of shot in the flesh of crippled or unretrieved waterfowl and in Charente‐Maritime, from eating crippled or dead mammals.

Other raptors at risk from lead poisoning and solutions to this problem are discussed.
Role of extrinsic factors in the control of clutch‐size in the Blue Tit Parus caeruleus
Authors: HAYWOOD SACHA
Published: April 2008

Extrinsic factors that play a role in the control of clutch‐size in Blue Tits Parus caeruleus were investigated. The disruption of ovarian follicular growth, and hence the cessation of egg‐laying, is caused by a stimulus generated by eggs present in the nest. The timing of this disruption varies among females during the laying period and may happen as late as after the laying of the eighth egg of the clutch; the larger the clutch, the later the disruption of follicular growth. The timing of follicular disruption is also related to ambient temperature because the proportion of female Blue Tits that cease to lay increases when higher temperatures occur toward the end of laying. It is suggested that the use of temperature to control clutch‐size may be adaptive because the food peak on which parents rely to feed their chicks is likewise affected by temperature.
Structure of a Brambling Fringilla montifringilla roost according to sex, age and body‐mass
Authors: JENNI LUKAS
Published: April 2008

In a winter roost of several hundreds of thousands of Bramblings Fringilla montifringilla, the composition of birds roosting at the periphery and of birds flying into the centre of the roost was studied regarding sex, age, size and body‐mass. At the periphery of the roost, more females were present than in the centre, and their proportion increased with decreasing density at the periphery. No significant difference in age classes was found between centre and periphery, but adults flew into the roost later than first year birds. Within sex‐age classes, birds in the centre were heavier but not larger than birds at the periphery. The difference in body‐mass between centre and periphery was more pronounced in small than in large birds within each sex‐age class.

Because strong competition for particular positions within the roost was observed, it is inferred that the quality of roosting positions varied and that females and/or light birds were displaced toward the periphery. Predation and microclimate are discussed as possible reasons for the variation in the quality of roosting positions and for the lower energy reserves of birds roosting at the periphery.
The function of aggressive chases by breeding Black and Red Kites Milvus migrans and M. milvus during the post‐fledging dependence period
Authors: BUSTAMANTE JAVIER , HIRALDO FERNANDO
Published: April 2008

Black and Red Kites Milvus migrans and M. milvus chase other raptors approaching their nests. The study of this behaviour during the post‐fledging period suggested that it reflects mainly, but not only, anti‐predator behaviour. The frequency of vigilance and aggressive chases decreased through the post‐fledging period as predicted by theoretical models of nest defence. Although predation risks were similar, Black Kites invested more time chasing intruders than did Red Kites. Black Kites, unlike Red Kites, chased away intruding juveniles, which may be interpreted as a behaviour to avoid investment in unrelated fledglings. Black Kites usually nest in loose colonies where the risk of, and selection pressures against, accidental investment in unrelated fledglings is likely to be greater than for Red Kites. Differences in aggressive chases by Black and Red Kites are better related to this than to different predation risks.
Parental age and reproduction in the Marsh Tit Paras palustris
Authors: SMITH HENRIK G.
Published: April 2008

In the Marsh Tit Parus palustris, breeding performance improved with the age of both the male and the female parent—older birds produced larger clutches earlier in the season. The effect of male age, however, was mainly due to a positive association with the age of the female. When the effect of laying date was accounted for, there was no additional effect of female age on clutch‐size. However, pairs with previous breeding experience laid larger clutches than newly formed pairs of the same age. There was some evidence that young females that laid late in the season were less likely to survive to breed again, leading to an age effect on reproductive performance. There was no evidence that individual birds laid earlier or produced larger clutches when they became older.
Adult survival of Black‐legged KittiwakesRissa tridactylain a Pacific colony
Authors: HATCH SCOTT A. , ROBERTS BAY D. , FADELY BRIAN S.
Published: April 2008

Breeding Black‐legged KittiwakesRissa tridactylasurvived at a mean annual rate of 0.926 in four years at a colony in Alaska. Survival rates observed in sexed males (0.930) and females (0.937) did not differ significantly. The rate of return among nonbreeding Kittiwakes (0.839) was lower than that of known breeders, presumably because more nonbreeders moved away from the study plots where they were marked. Individual nonbreeders frequented sites up to 5 km apart on the same island, while a few established breeders moved up to 2.5 km between years. Mate retention in breeding Kittiwakes averaged 69% in three years. Among pairs that split, the cause of changing mates was about equally divided between death (46%) and divorce (54%). Average adult life expectancy was estimated at 13.0 years. Combined with annual productivity averaging 0.17 chick per nest, the observed survival was insufficient for maintaining population size. Rather, an irregular decline observed in the study colony since 1981 is consistent with the model of a closed population with little or no recruitment. Compared to their Atlantic counterparts, Pacific Kittiwakes have low productivity and high survival. The question arises whether differences reflect phenotypic plasticity or genetically determined variation in population parameters.
The nesting biology of Archbold's Bowerbird Archboldia papuensis and a review of that of other bowerbirds (Ptilonorhynchidae)
Authors: FRITH CLIFFORD B. , FRITH DAWN W.
Published: April 2008

Thirteen active and 14 old Archbold's Bowerbird Archboldia papuensis nests were studied in Tari Gap, Southern Highlands, Papua New Guinea. Clutch size was one egg. At two nests, only one‐parent nest attendance was observed. Incubation and nestling periods were considerably longer and nestling growth slower than in other bowerbird species, possibly reflecting adaptation to a colder environment depauperate in insects. Of 382 identified nestling meals, 71% were exclusively fruit (14 spp. identified) and 29% were animal. Of 112 animal meals, 30% were skinks (Reptilia), 28% were small arthropods, 17% were beetles and the remainder (25%) were larger insects, pieces of nestling birds and unidentified items. Most active nests were built adjacent to older nests and the significance of this is discussed.
The effects of raptor predation on wintering wader populations at the Tyningharne estuary, southeast Scotland
Authors: CRESSWELL WILL , WHITFIELD D. PHILIP
Published: April 2008

Raptor predation on waders was studied by direct observation of raptors hunting a known wader population and subsequent recovery of dead waders. In each of three winters, raptor predation was shown to be the most significant cause of mortality in most small wader species, Sparrowhawks Accipiter nisus, Merlins Falco columbarius and Peregrines F. pere‐grinus attacked waders with a success rate of 11.6%. 8.8% and 6.8%, respectively. Most waders attacked or found dead were Redshank Tringa totanus and Dunlin Calidris alpina; most were killed by Sparrowhawks. Kleptoparasitism of raptors carrying prey by Carrion Crows Corvus corone significantly increased the winter mortality of some waders. Redshank populations were most affected by raptor predation: over 50% of the total population (which was found to be closed during most of the winter) and over 90% of the juvenile population were taken in two winters: juvenites were more likely to be killed by raptors.
Incubation routine, body mass regulation and egg neglect in the Blue Petrel Halobaena caerulea
Authors: CHAURAND THIERRY , WEIMERSKIRCH HENRI
Published: April 2008

The incubation routine and mass changes of male and female Blue Petrel Halobaena caerulea were studied at the Kerguelen Islands to investigate factors influencing the durations of incubation stints and foraging trips at sea and the factors determining nest desertion and return to the nest.

The body mass at the start of an incubation shift and also when the bird was relieved varied throughout the incubation period, whereas the mass when birds deserted the nest was stable. Birds deserted the nest when their mass decreased to threshold, independent of the duration of the fast. Temporary egg neglect was observed in successful as well as in unsuccessful breeding attempts, but it increased the risk of breeding failure. The net and daily massgained at sea during the second part of the incubation period were higher than during the first part, suggesting an increase in food availability. During the first part, the mass gained at sea and time spent foraging were inversely related to the mass of the bird before it left the burrow, whereas a similar relationship did not occur thereafter.

The results suggest the occurrence of a fixed mass threshold when birds decide to leave the nest if not relieved by their partner. The mass when a bird left its nest inffuenced the time spent foraging or mass gained when food was scarce. Although decision rules to leave the nest or return from the sea are related to body condition. the possibility of neglecting the eggs temporarily enables Blue Petrels to regulate the trade‐off between risks of breeding failure and risks of an increase in adult mortality. A model for behavioural decision to stop incubating or stop feeding, based on a variable set point, is proposed.
Song mimicry and species associations of west African indigobirds Vidua with Quail‐finch Ortygospiza atricollis, Goldbreast Amandava subflava and Brown Twinspot Clytospiza monteiri
Authors: PAYNE ROBERT B. , PAYNE LAURA L.
Published: April 2008

The brood‐parasitic indigobirds Vidua spp. mimic the songs of their foster species, which for many species of indigobirds are Lagonosticta firefinches. We report additional associations of indigobirds with estrildid finches in west Africa. Quail‐finch Indigobirds Vidua nigeriae in northern Cameroon mimic the songs of Quail‐finch Ortygospiza atricollis. Gold‐breast Indigobirds Vidua raricola in Cameroon and Sierra Leone mimic the songs of Gold‐breast Amandava subflava. Both indigobirds are distinct in male breeding plumage from other indigobirds. Also, a population of blue indigobirds Vidua sp. in Cameroon mimics the songs of Brown Twinspot Clytospiza monteiri. They are similar in colour and size to blue indigobirds associated with Dark Firefinch L. rubricata and Black‐bellied Firefinch L. rara. Mouth patterns of fledged young Quail‐finch Indigobirds and Goldbreast Indigobirds resemble those of their song‐model and presumed foster species, but the mouth pattern of a fledged young associated with the Brown Twinspot mimic was not distinct from the mouth of young Black‐bellied Firefinch. The field observations show associations of certain species of indigobirds with finches other than the firefinches. The results are consistent with mitochondrial DNA estimates of greater genetic similarity among indigobirds than among their foster species. The field observations support the hypothesis of evolutionary associations of the brood parasite and foster species by colonization with switching from one foster to another rather than by cospeciation.
Visual fields in the Stone‐curlew Burhinus oedicnemus
Authors: MARTIN GRAHAM R. , KATZIR CADI
Published: April 2008

The Stone‐curlew Burhinus oedicnemus is a short‐billed terrestrial wading bird (Burhinidae; Charadriiformes) which forages primarily for surface living invertebrates in open, sparsely vegetated habitats during twilight and nighttime. Visual field topography in restrained alert birds was investigated using an ophthalmoscopic reflex technique. The visual fields have the following features: (1) Eye movements of significant amplitude appear to be absent. (2) The retinal binocular field is relatively small, with the bill placed near its centre. It extends vertically through 80° in the median sagittal plane with a maximum width of 18° occurring 5° above the bill. (3) With the head in a typical posture (eye‐bill‐tip angle approximately 15° below the horizontal), the binocular field stretches from 60° below to 20° above the horizontal. (4) The blind area behind the head is relatively narrow (15° at the horizontal), giving the bird near panoramic vision in the horizontal plane, but the widest blind area (32°) occurs directly above the head. (5) Monocular retinal fields in the horizontal plane are 182° wide and are asymmetric about the optic axis. (6) There is a blind sector of 7–12° at the margin of the optical fields, indicating that binocular field widths are not maximized. Interspecific comparisons of these visual field features suggest that the foraging of Stone‐curlews is guided primarily by visual cues.
Genetic evidence for extra‐pair fertilizations in a monogamous passerine, the Great Tit Parus major
Authors: BLAKEY JEREMY K.
Published: April 2008

The incidence of extra‐pair paternity in a Great Tit Parus major population at Wytham Wood, Oxford, in 1985–1987 was determined using two polymorphic allozymes. In 831 nestlings from 94 broods, 27 genetic exclusions were detected in 25 (3%) nestlings from 16 broods. Seven (44%) of these broods contained offspring that excluded the putative male parent from being the genetic parent. The distribution of exclusion types indicated that excluded offspring were the result of fertilizations by extra‐pair males and not of egg‐dumping. The true frequency of extra‐pair paternity was estimated as 14% of offspring. These results suggest a mixed reproductive strategy for males in which they breed mo‐nogamously whilst simultaneously seeking extra‐pair matings with females of other pairs.
Age at first breeding, philopatry and breeding site‐fidelity in the Lapwing Vanellus vanellus
Authors: THOMPSON PATRICK S. , BAINES DAVID , COULSON JOHN C. , LONGRIGG GEOFF
Published: April 2008

Breeding Lapwings Vanellus vanellus were studied in the Eden Valley (Cumbria) and in Teesdale (County Durham) between 1990 and 1992. A total of 300 adult Lapwings and 801 near‐fledged young were uniquely colour‐ringed. Breeding adults were highly site‐faithful, almost always nesting in the same or an adjacent field in successive years. Second‐year birds were less site‐faithful, with more birds nesting in adjacent and other fields and fewer in the same field in successive years. In Teesdale, 74% of colour‐ringed young Lapwings returned in their first or second year of life to within 5 km from where they hatched. In contrast, in the Eden Valley only 37% of young birds in their first or second year of life returned to within 5 km from where they hatched. From an analysis of British ringing recoveries in April and May, 61% of Lapwings were recovered within 10 km from where they were ringed as chicks. A further 11% were recovered more than 100 km from where they were ringed. Young Lapwings were highly philopatric, with 45% of males and 52% of females breeding in the same field or a field adjacent to where they hatched. The majority of Lapwings (67%) began breeding at 1 year old. Of the remaining birds, 27% bred for the first time when 2 years old and 6% for the first time in their third year of life. There was no difference between the sexes. Chicks hatching and subsequently fledging late in the season returned less frequently to the study areas in subsequent years than did chicks hatching earlier in the season.
Variation in the developmental timing of flight‐feather growth in nestling birds
Authors: REDFERN CHRISTOPHER P. F.
Published: April 2008

The timing of primary‐feather development in relation to growth in body‐mass varies considerably between altricial species. This variation relates, at least in part, to differences in nesting habits: species nesting in relatively well‐protected nest sites, such as holes, start primary‐feather development later than altricial species using open‐cup nests. For the latter ‘open‐nesting’ species, the timing of primary‐feather development also tends to show an allometric correlation with adult body‐size. Since primary‐feather development takes longer, rerative to growth in body‐mass, in small species than in large ones, these data suggest that, for small species, there will be an important selective advantage in using relatively secure nest sites.
Factors affecting nest site selection and nesting success in the Common Eider Somateria mollissima
Authors: ROBERTSON GREGORY J.
Published: April 2008

Nesting site selection and nesting success in Common Eiders Somateria mollissima were studied over a 3‐year period (1991–1993) in the Mast River delta (58o24'N, 94o24'W), 40 km east of Churchill, Manitoba, Canada. Eiders preferentially nested on islands that had incubating Lesser Snow Geese Anser caerulescens caerulescens on them; this effect was also seen between years on the same islands. Eiders which nested on islands with geese had a reduced chance of having eggs taken by predators during egg‐laying and had a greater chance of hatching once incubation had begun, independent of the number of other eiders nesting on the island. The distance to a goose nest was less in nests which did not lose eggs prior to incubation than in those which did, but there was no difference in the distance to a goose nest in eider clutches which did or did not hatch. Artificial eider eggs placed closer to goose nests had a lower probability of being predated than those placed farther away. Nests on islands farther up the river and farther from the mainland had higher nesting success, presumably because these nesting islands were inaccessible to Arctic Foxes Alopex lagopus.