bluuebunny/crossref_metadata_2025 huggingface dataset:
Flexible foraging techniques in breeding Cormorants Phalacrocorax carbo and Shags Phalacrocorax aristotelis: benthic or pelagic feeding?
Authors: GRÉMILLET D. , ARGENTIN G. , SCHULTE B. , CULIK B. M.
Published: April 2008

A total of 8772 dive durations were recorded during 117 diving bouts in five Cormorants Phalacrocorax carbo and five Shags Phalacrocorax aristotelis breeding at the Chausey Islands, France. Diet of the birds was assessed by analysis of 526 pellets containing 13,016 otoliths. Radio‐tracking data indicated that Cormorants fed exclusively on pelagic fish during social fishing (5% of the trips) and executed 11% pelagic and 60% benthic dives during the remaining 95% of the trips. In Shags, 44% of all trips were pelagic, and the remaining 56% included 9% pelagic and 67% benthic dives. The proportions of benthic to pelagic dives varied widely between dive sequences of single birds and between individuals and sexes in both species. The prey spectrum of the Cormorants contained both pelagic (29%) and benthic fish (67%) and confirmed considerable flexibility in foraging. In Shags, birds may adjust their diving patterns to accommodate the behaviour of their main prey, sandeels Ammodytidae (87% of all prey). We propose that the wetability of plumage may explain this flexibility.
Individuality in Corncrake Crex crex vocalizations
Authors: PEAKE T. M. , McGREGOR P. K. , SMITH K. W. , TYLER G. , GILBERT G. , GREEN R. E.
Published: April 2008

Vocal individuality has potential for the monitoring of bird species that are otherwise difficult to observe. In this study we assessed the potential of this technique for the monitoring of the globally threatened Corncrake Crex crex based on the analysis of calls recorded in Ireland and Scotland in 1993 and 1994. Discriminant function analysis correctly attributed >80% of individual calls based on five temporal parameters. A high level of individual distinctiveness was also found in the fine temporal structure of calls. When information on fine structure was added to the discriminant function analysis, classification of calls to individuals was improved to 100%. The structure of an individual's call was found to be consistent over the 2‐year period. This study highlighted the problemsassociated with setting criteria for re‐identifying individuals by calls. The consequences of these problems and the potential of vocal individuality for providing monitoring information in this species are discussed.
Density‐dependence in the bird populations of anoak wood over 22 years
Authors: NEWTON I. , ROTHERY P. , DALE L. C.
Published: April 2008

Annual counts of the five commonest bird species in an oak wood in southeastern England over 22 years showed evidence for density‐dependent feedback in their year‐to‐year fluctuations. The counts also showed evidence for effects of winter weather in two species (Wren Troglodytes troglodytes and Robin Erithacus rubecula). Evidence for density‐dependence in the Wren was greatly strengthened when effects of winter weather were included in the analysis.
Visual fields in the Black‐crowned Night Heron Nycticorax nycticorax: nocturnality does not result in owl‐like features
Authors: KATZIR GADI , MARTIN GRAHAM R.
Published: April 2008

Compared with diurnally active species, the eyes of nocturnally active herons (Ardeidae) are relatively larger and more widely separated. These features are found in comparisons between the nocturnally foraging Black‐crowned Night Heron Nycticorax nycticorax and the diurnally active Cattle Egret Bubulcus ibis. Casual viewing of the Black‐crowned Night Heron gives the impression of a somewhat owl‐like appearance, with an apparently wide degree of binocular overlap. Visual fields and eye movements were determined in two alert, restrained Black‐crowned Night Herons with the use of an ophthalmoscopic technique. A wide degree of binocular overlap was not confirmed, and the Black‐crowned Night Heron's visual field closely resembles those of diurnally foraging herons (Western Reef Heron Egretta gularis schistacea, Squacco Heron Ardeola ralloides, Cattle Egret). The Black‐crowned Night Heron's binocular field is vertically long and narrow (maximum width 22d̀), with the bill placed approximately at the centre. Monocular and cyclopean field widths in the horizontal plane equal 171d̀ and 320d̀, respectively. Retinal binocular overlap can be abolished by eye movements. There is a blind sector (10–13d̀ wide) at the margin of each eye's optical field, and this results in the functional retinal binocular field being much narrower than the optical binocular fields. It is these blind sectors which give rise to the appearance of a much wider binocular field. The visual field characteristics of this heron species may be best understood in relation to the foraging technique of capturing agile, evasive prey directly in the bill. The comparatively large size of the Black‐crowned Night Herons' eyes may be associated with activity over a wide range of natural light levels but does not give rise to binocular fields larger than those of diurnal heron species.
Incubation and brooding rhythm of the Cape Petrel Daption capense at Nelson Island, South Shetland Islands, Antarctica
Authors: WEIDINGER KAREL
Published: April 2008

Incubation and brooding performance of the Cape Petrel Daption capense at Nelson Island, South Shetland Islands, Antarctica, in the 1991 ‐1992 austral summer is reported in detail and compared with data from two other areas. There was an inverse relationship between the mean foraging trip length and mean peak weight of chicks. Variation in shift length throughout incubation resulted from a combination of seasonal effects (food supply) and behavioural adjustment to hatching. The length of the last incubation shift was independent of its number but decreased with date of initiation. The average weight of nestattending birds increased steadily during the incubation period and at the same rate in both sexes. Females attained seasonal peak body‐weight before the egg hatched, whereas males just recovered their pre‐breeding weight. Males took on a slightly larger share of incubation (52%, range 40–63%) and invested more time in mutual nest attendance. Length of foraging trips varied consistently in pairs and individuals, its repeatability being twice as high in females as in males. The incubation performance of individual females (length of the first and an average foraging trip) was correlated with the size of the egg they had laid and also to subsequent chick growth and fledging success. There was a tendency in successful pairs to spend more time together at the nest and to have shorter foraging trips. I suggest that variation in breeding performance among pairs was mainly a result of individual variation in female quality, with pairs where the female contributed more to incubation being more successful. There is little evidence that egg losses were caused by parental errors.
A new species of firefinch Lagonosticta from northern Nigeria and its association with the Jos Plateau Indigobird Vidua maryae
Authors: PAYNE ROBERT B.
Published: April 2008

A firefinch of the Jos Plateau, northern Nigeria, is described as a new species, Rock Fire‐finch Lagonosticta sanguinodorsalis. This firefinch has distinctive songs and a distinctive habitat—bushy and grassy rocky outcrops on the plateau and inselbergs to the north and east. It has a blue‐grey bill, red back in the male and reddish brown back in the female and juvenile and broad primaries in both the adult and juvenile. It appears most closely related to the Mali Firefinch Lagonosticta virata and the Chad Firefinch Lagonosticta umbrinodorsalis. Its songs are mimicked by the brood‐parasitic Jos Plateau Indigobird Vidua maryae, which occurs within the range of the firefinch and whose songs led to the discovery of the firefinch. The songs of the firefinch, the song mimicry of the indigobird and the apparent continuity of song mimicry across 27 years indicate a unique association of this distinct pair of species.
Experimental evidence for the relationship between food supply, parental effort and chick survival in the Lesser Black‐backed Gull Larus fuscus
Authors: BUKACIŃSKI DARIUSZ , BUKACIŃSKA MONIKA , SPAANS ARIE L.
Published: April 2008

We studied breeding success, chick growth, parental effort and chick behaviour in two groups of Lesser Black‐backed Gulls Larus fuscus whose chicks were provided with additional food until 7 days after hatching or until fledging. These data were compared with those from control pairs which we studied simultaneously to test the hypotheses that food was in short supply during the chick stage at the colony site and that in such circumstances the behaviour of adults and young is mainly responsible for the low success. Pairs whose chicks were fed with additional food until fledging showed a higher fledging success than control pairs (intermediate for pairs of first experimental group). During the first week after hatching, experimental adults of both groups were present together at the territory for longer than control pairs. In adult females of experimental pairs, the length of feeding trips was shorter than in females of control pairs, whilst the rate of chick feeding was more frequent in the experimental broods. After the chicks were 7 days old, differences were significant only for the experimental pairs whose chicks were provided with additional food until fledging. Chicks fed until fledging showed a higher daily mass and wing‐length increments and reached a higher fledging mass at an earlier age than both control chicks and chicks which were provided with additional food until day 7. Starvation occurred only in control chicks and in chicks of the first experimental group after we had stopped providing food. When food was in short supply, fledging success of gulls was adversely affected as a result of both starvation (because of the lower feeding rates of chicks) and a higher predation rate (arising from changes in behaviour of both adults and chicks).
Foraging movements of the Shy Albatross Diomedea cauta breeding in Australia; implications for interactions with longline fisheries
Authors: BROTHERS NIGEL , GALES ROSEMARY , HEDD APRIL , ROBERTSON GRAHAM
Published: April 2008

Satellite telemetry was used to identify the foraging zones of Shy Albatrosses Diomedea cauta breeding at two sites off Tasmania, Australia (Albatross Island in western Bass Strait and Pedra Branca to the south) to assess their level of interaction with longline fisheries. Adult birds from both colonies fed locally both in and outside the breeding season. Breeding birds from Albatross Island foraged over the Australian continental shelf or slope waters off northwest Tasmania, while those from Pedra Branca foraged between the colony and the southeastern edge of the continental shelf. The distances travelled by the birds and the duration of their foraging trips varied during the breeding cycle and tended to decrease as eggs approached hatching. Adults which were tracked near the end of the breeding season (March‐April, n= 7 birds) deserted their chicks prematurely, and while dispersing further than incubating or brooding birds, they remained over the continental shelf and slope waters off southeast Australia. Home range analyses indicated 41% overlap between foraging zones of birds during successive breeding stages. Dispersal during the postbreeding period extended the foraging zones with less overlap between individuals (10% for Albatross Island and 19% for Pedra Branca). The recent contraction of the Japanese Southern Bluefin Tuna longline fishery to the south and east coasts of Tasmania has resulted in extensive overlap with adult Shy Albatrosses from Pedra Branca, but appears to pose a minimal threat to adult birds from Albatross Island. Coupled with the concomitant increase in the Australian domestic tuna longlining industry, adult Shy Albatrosses from southern Tasmania (Pedra Branca and the Mewstone) are vulnerable to incidental capture through out their annual cycle.
Patterns of activity and burrow attendance in Cory's Shearwater Calonectris diomedea as revealed by a novel logging technique
Authors: GRANADEIRO J. P. , BURNS M. D. , FURNESS R. W.
Published: April 2008

We monitored the attendance and activity of Cory's Shearwater Calonectris diomedea on Berlenga Island, Portugal, during the breeding season. To achieve this, we developed a novel logging technique to record the date and time of entrances and departures from the burrows, as well as the identity of each member of a pair. The technique enabled nonintrusive assessment of the activity of burrow‐nesting animals over prolonged periods and provided very reliable information. Our study showed that males attended the nests more frequently than females during the pre‐laying and chick‐rearing periods. We did not find such differences during the incubation period, and both members spent similar amounts of time incubating the eggs. An index of activity (denned as number of entrances plus exits from the nest) achieved higher scores during the pre‐laying and incubation periods,

but the activity decreased significantly during the chick‐rearing period. We did not find any effect of moonlight on the levels of activity, hour of arrival at the colony or time spent inside the burrows in breeding birds.
The former status of the Crane Grus grus in Britain
Authors: BOISSEAU S. , YALDEN D.W.
Published: April 2008

The place‐name, archaeological and documentary evidence for the former widespread distribution and abundance of the Crane Grus grus in Britain (mostly England) is reviewed. There appear to be nearly 300 place‐names which include some reference to Cranes very widely distributed across Britain; at least half of the sample has the name associated with other place‐name elements relating to water (e.g. fen, mere, lake). No other wild bird appears in so many place‐names. Crane bones are also quite common in archaeological sites, although they are absent from most cave sites; they are reported from at least 78 excavations. The evidence of bestiaries, illustrated manuscripts and other documentary sources makes it clear that the Crane was a well‐known bird, clearly distinguished from the Grey Heron Ardea cinerea. All three lines of evidence confirm that the Crane was a breeding bird in Britain, not just a winter visitor.
Summer distribution of Red‐legged Partridges Alectoris rufa in relation to water availability on Mediterranean farmland
Authors: BORRALHO RUI , RITO ANA , REGO FRANCISCO , SIMÕES HELENA , PINTO PEDRO VAZ
Published: April 2008

The suggestion that the summer distribution of Red‐legged Partridges Alectoris rufa in the Mediterranean region is determined by the availability of surface water was examined on the agricultural farm, Alto Alentejo, southern Portugal. Partridge coveys were surveyed between 15 July and 15 August in 1993 and 1994. Using a vector‐based Geographic Information System, we assessed, for each covey location and for the locations of a double number of random points, the distance to the nearest water point, distance to field boundaries, distance to water lines and land use classes. Univariate comparisons were made between the two groups of locations, and three multivariate logistic models were fitted through forward stepwise selection to the 1993, 1994 and pooled data sets to estimate the probability of sighting partridge coveys in the study area. Distance to water was significantly lower for partridge locations than for random points in both years and was the only variable selected for all logistic models. Apart from water availability, Red‐legged Partridge locations were also affected by land use and distance to field boundaries.
Patterns in the geographic ranges of the world's woodpeckers
Authors: BLACKBURN TIM M. , LAWTON JOHN H. , GASTON KEVIN J.
Published: April 2008

We used data on the world's woodpeckers to test for patterns in the geographic distributions of a single group of closely related species. The frequency distribution of woodpecker geographic range sizes is approximately lognormal. Most variation in range sizes is explained by differences between species within genera; that is, range size seems to be an evolutionarily labile trait. The largest woodpecker ranges are found in Eurasia, both when absolute differences are compared and when range size is measured as a proportion of estimated available habitat. Notably, there is a negative relationship between the mean range sizes attained by species in a genus or tribe in South America and the mean ranges attained by species in the same tribe or genus in North America. Large‐bodied species tend to be more widely distributed and to live at higher latitudes, but both tendencies disappear if the taxonomic relatedness of species is controlled for. Species living at high latitudes also tend to be more widely distributed. This relationship seems largely due to the effect of North American woodpeckers, which show it even when the taxonomic relatedness of species is controlled. Small continents generally have more woodpecker species than do large ones. Woodpecker geographic range sizes are smaller the more woodpecker species inhabit an area. Species show less overlap in their geographic ranges with species of similar than with species of dissimilar body size. The implications of these results for our understanding of patterns in geographic range sizes are discussed.
Clutch size, brood size and brood emergence in the Marbled Teal Marmaronetta angustirostris in the Marismas del Guadalquivir, southwestern Spain
Authors: GREEN ANDY J.
Published: April 2008

The first detailed study of the breeding biology of the globally threatened Marbled Teal Marmaronetta angustirostris is presented, using data from the Marismas del Guadalquivir in southwestern Spain. Complete clutches, with 9–20 eggs, were recorded from 28 April to 27 July. Excluding clutches of over 14 eggs (likely to be intraspecifically parasitized), the mean clutch size was 11.8, larger than that reported for almost all other Anatidae species. Broods hatched from May to early August (later than sympatric duck species), with a peak in mid‐late June and significant annual variation in date. Brood sizes were exceptionally high, declining from a mean of 10.9 in the first week of age to 8.5 when fully feathered (at 42 days or more). Duckling mortality was concentrated in the first 2 weeks after hatching. Nine percent of broods had 15–23 ducklings, largely as a result of nest parasitism. Brood size decreased strongly with hatching date and varied significantly between years. Data from across the species' range showed that breeding occurs later at more northerly latitudes. A recent decline in the Marbled Teal in the Marismas is linked with its late breeding season. Anthropogenic changes have reduced the duration of flooding in the natural marshes of Donana National Park, which now dry out by August, before this species has completed breeding
Population declines and reproductive performance of Skylarks Alauda arvensis in different regions and habitats of the United Kingdom
Authors: CHAMBERLAIN DAN E. , CRICK HUMPHREY Q.P.
Published: April 2008

Declines in the number of breeding Skylarks Alauda aruensis and changes in their reproductive performance were analysed using data from two long‐running surveys co‐ordinated by the British Trust for Ornithology: the Common Birds Census and the Nest Record Scheme. In the UK, the number of breeding Skylarks declined by approximately 55% between 1975 and 1994. This decline was steepest in agricultural habitats and in regions associated with intensive agriculture. In contrast, Skylark reproductive performance per nest, in terms of clutch size, brood size and post‐hatching survival rate of nests, showed a general improvement over time. This improvement was greatest in intensively farmed agricultural habitats. Therefore changes in reproductive performance per nesting attempt were probably not responsible for the decline in numbers. It is inferred that possible causes of the decline of the Skylark are: reductions in the number of breeding attempts per pair per season, reductions in the proportion of birds attempting to breed, and increased mortality outside the breeding season.
Breeding success and predation on artificial nests of the endemic pigeons Bolle's Laurel Pigeon Columba bollii and White‐tailed Laurel Pigeon Columba junoniae in the laurel forest of Tenerife (Canary Islands)
Authors: HERNÁNDEZ MIGUEL A. , MARTÍN AURELIO , NOGALES MANUEL
Published: April 2008

Breeding success and nest predation effects on the two Canarian endemic pigeons, Bolle's Laurel Pigeon Columba bollii and White‐tailed Laurel Pigeon C. junoniae, were studied during 1995 in five zones of laurel forest on Tenerife Island. Nest predation was the more important cause of nesting failure of both species (88%), but principally affecting the White‐tailed Laurel Pigeon. Experiments using artificial nests showed a greater predation on the ground than in trees and a lower predation in the February‐March period than in June‐July and September‐October. The abundance of predators, estimated by bait consumption, showed a similar seasonal pattern, while fruit availability decreased over time from the first to third period. Predators identified by automatic cameras showed that Black Rat Rattus rattus was the major nest predator of both pigeons. These general patterns of nest predation affect the White‐tailed Laurel Pigeon, which breeds on the ground mainly during April‐July, much more than Bolle's Laurel Pigeon, which breeds in trees, especially in February‐June. All seems to indicate that rats are the key factor causing the scarcity of the White‐tailed Laurel Pigeon on Tenerife.
Importance of feeding ecology to the reproductive success of Blackbirds Turdus merula nesting in rural habitats
Authors: CHAMBERLAIN DAN E. , HATCHWELL B.J. , PERRINS C.M.
Published: April 2008

The feeding ecology of Blackbirds Turdus merula breeding in contiguous woodland and farmland habitats was studied over three years. The aim of the study was to investigate how reproductive success was influenced by nestling diet and the provisioning rates of parents feeding nestlings. Parental provisioning rates increased with brood size, and consequently individual nestlings were no lighter in larger broods. None of the environmental factors measured had strong effects on parental provisioning rate. The nestling diet was dominated by caterpillars and earthworms, the former occurring in a short period in the middle of the breeding season. The availability of earthworms was higher in woodland and was dependent on rainfall in farmland. Nestling mass and provisioning rates were marginally higher under predominantly earthworm diets. Nestling mass increased with rainfall in farmland only, and was higher in farmland than in woodland or woodland‐edge, although it is doubtful whether this result is of any significance for fledgling survival. Overall, Blackbirds were able to provision their nestlings adequately throughout the breeding season across a range of conditions. There was no evidence to suggest that reproductive success was constrained by aspects of feeding ecology within the natural range of brood size.
Response to weather and light conditions of migrating Whooper Swans Cygnus cygnus and flying height profiles, observed with the Argos satellite system
Authors: PENNYCUICK C.J. , BRADBURY T.A.M. , EINARSSON ÓLAFUR , OWEN MYRFYN
Published: April 2008

Ten satellite tracks of Whooper Swans migrating between Iceland and Britain or Ireland were analysed in relation to detailed weather and astronomical data. Surface pressure, visibility, cloud cover, precipitation intensity and type, sun altitude and moon altitude were estimated separately for each of 414 location points, of which 217 were over land or offshore islands, and 197 were over the open sea. Height profiles for four northbound and four southbound flights included two swans that flew continuously for most or all of the sea crossing, one of which reached 1856 m asl, the maximum height recorded. The others flew low, and landed often on the water, sometimes for prolonged periods. Elapsed times for the sea crossing varied from 12.7 to 101 hours. Statistical analysis showed that the swans tended to move onward during the sea crossings, provided that the altitude above the horizon of either the sun or the moon was higher than ‐4d̀, and also that the visibility was greater than 2 km; otherwise, they tended to stop on the water. This effect was seen only when the swans were crossing the open sea, not when they were flying over land or islands. It was interpreted as suggesting that they need a visible horizon to navigate when out of sight of land. If this inference is correct, it would eliminate the possibility that the swans use inertial navigation, but strengthen the case for celestial navigation.
Effects of testosterone on growth, plumage pigmentation, and mortality in Black‐headed Gull chicks
Authors: ROS ALBERT F.H.
Published: April 2008

In the Black‐headed Gull Larus ridibundus, sibling chicks defend small territories against conspecifics with testosterone‐dependent aggressive behaviour. The energetic requirements for the performance of this behaviour may trade off against the energetic requirements for growth. There are indications that testosterone suppresses growth in birds and, therefore, regulate this trade‐off. In this study, the effect of testosterone on growth and plumage pigmentation of Black‐headed Gull chicks was analysed. Young chicks in small groups were treated for ten days with testosterone or sham treated. Testosterone‐treated birds showed decreased growth rate (daily increase in body mass, head‐bill length and tarsus‐length) and a marked decrease in juvenile pigmentation of the plumage (tail‐bar, back, and secondary coverts). Field measurements revealed a negative correlation between nest density, which correlates positively with aggressive behaviour of adults, and plumage coloration. Furthermore, these measurements showed an increase in mortality of chicks that had low levels of pigmentation early in life. The data suggest that chicks face a testosterone‐regulated trade‐off between growth and territory defence.
Population dynamics of the White Stork Ciconia ciconia in western France
Authors: BARBRAUD CRISTOPHE , BARBRAUD JEAN‐CLAUDE , BARBRAUD MONIQUE
Published: April 2008

Population dynamics of the White StorkCiconia ciconiawere studied in Charente‐Maritime, France from 1978 to 1996, during which time the number of breeding pairs increased from one to 44. Modal age at first return and first breeding were 2.4 and 3.4 years, respectively. White Storks produced an average of 3.2 fledglings per nest. The average number of fledglings per nest decreased with increasing nest density, probably because of an increase in the number of interactions between breeding birds. Nests surrounded by marshes had slightly greater productivity than nests on peripheral sites. Individual White Storks followed an annual breeding cycle and attempted to breed in 97% of seasons once mature. Nest‐site and mate fidelity were high (88 and 83%, respectively). Immigration rate was nearly twice that of emigration during the last few years of the study and recruitment was close to 30%, although underestimated. We modelled survival and recapture probabilities using capture‐mark‐recapture methods. Adult survival was found to be dependent on age, but not sex. Survival of younger birds varied greatly over the years, whereas survival of older birds was relatively constant and averaged 78%. Survival rates of young birds wintering in the Sahel zone were positively linked to the amount of rainfall in their wintering area. The proximate reason for the population increase was probably immigration of birds from other European countries, probably encouraged by a high adult survival rate. Ringing recoveries indicate that some birds winter in Spain and the high adult survival rate may reflect a change in migratory pattern in recent years. Finally, reproductive success was relatively high during the study.
Rainfall as a breeding stimulus and clutch size determinant in South African arid‐zone birds
Authors: Lloyd Penn
Published: April 2008

Rainfall is known to be a stimulus for initiating breeding in arid‐zone birds, but its influence on clutch size is unknown for most southern African birds. The breeding activity of nine out of 11 species studied in the arid Nama Karoo biome of South Africa increased markedly after appreciable rainfall. Some resident insectivores did breed in the absence of rainfall, even under drought conditions, but also laid eggs within one week of small rain showers. Nomadic granivores required more substantial rainfall to stimulate what was usually a synchronized, population‐wide breeding response. The timing and length of the breeding season was dependent on the integrated effect that rainfall and temperature had on the growing season of the vegetation. Over 50% of the 11 species studied showed evidence of an increase in clutch size following large rainfall events. Grey‐backed Finchlark Eremopterix verticalis began laying larger clutches within one week of a rainfall stimulus, illustrating how rapid this response can be.
Natural selection on tail and bill morphology in Barn Swallows Hirundo rustica during severe weather
Authors: Brown Charles R. , Brown Mary Bomberger
Published: April 2008

An unusual six‐day period of cold, rainy weather caused mortality among Barn SwallowsHirundo rusticain southwestern Nebraska, USA, in May 1996. We compared birds that died during the cold to those still alive when the severe weather ended. Among males, survivors had significantly longer culmens and significantly less variance in outer‐tail asymmetry than non‐survivors. Among females, survivors had significantly longer outer tails and significantly less variance in outer‐tail length, overall body size and outer‐tail asymmetry than non‐survivors. Larger birds in general and those with less asymmetry in wing and outer tail tended to be favoured during this weather event. Long tails may reflect condition in females and, along with high levels of symmetry in wing and outer tail, improve foraging efficiency during extreme conditions. Males with long tails did not appear to suffer survival costs. Larger size probably allows more fat to be stored and may confer thermal benefits to swallows during late spring cold snaps. Similar mortality events have apparently occurred in the study area on only one other occasion since 1875.
Reproductive biology of the endangered Ouvea Parakeet Eunymphicus cornutus uvaeensis
Authors: Robinet Olivier , Salas Michel
Published: April 2008

The reproductive biology of the endangered Ouvea ParakeetEunymphicus cornutus uvaeensis, an endemic subspecies of Ouvea island (Territory of New Caledonia, Southwest Pacific) was studied from June 1994 to February 1996. Breeding was recorded from early August until late January. All nests were sited in cavities of native forest trees, 90% of them inSyzygiumsp. andMimusopssp. Mean clutch size was 2.9 eggs (range 2–3), and double clutches were recorded. Incubation lasted 21 days and the nestling period averaging 43 days. An average of 1.65 chicks fledged per nest but only 0.75 per breeding pair were still alive 30 days after fledging. The main causes of chick loss were starvation of the third sibling during the first week due to hatching asynchrony, raptor (presumably Brown Goshawk) predation of fledglings and human harvest for the pet trade. Growth curves and multiple regressions of weight, culmen‐width and ‐length, tarsus‐ and wing‐length, showed that wing‐length was a good predictor of age, and that there were significant differences between the sexes for weight and culmen‐width. The pattern of the breeding season, brood reduction, nest‐site characteristics and presumed size of breeding territories suggest that both food and availability of suitable nest‐sites may be factors limiting breeding productivity. Proposals for conservation of this endangered bird are presented.
New brush‐finch Atlapetes from Peru
Authors: Valqui Thomas , Fjeldså Jon
Published: April 2008

We describe a brush‐finch (Emberizidae: Atlapetes) from central Peru, where it inhabits humid scrub on both sides of the deep canyon formed where the Rio Mantaro intersects the eastern Andean ridge. The species probably has a very restricted range. In another paper in this issue, by J. Garcia‐Moreno and J. Fjeldså, its phylogenetic relationships and taxonomic rank are discussed in a broader context, based on mtDNA data.
Re‐evaluation of species limits in the genus Atlapetes based on mtDNA sequence data
Authors: Garcia‐Moreno Jaime , Fjeldså Jon
Published: April 2008

Brush‐finches of the genus Atlapetes present a complicated pattern of differentiation along the Andes. Forms with different colours may replace each other sharply at different altitudes on the same slopes, in similar humid habitats on different slopes or on adjacent humid and semi‐humid slopes. In the current classification, grey and yellow‐and‐green species are placed in different groups, and similar‐coloured populations replacing each other in corresponding ecological zones on different slopes are ranked as subspecies of the same species. However, Remsen and Graves have suggested that different‐coloured forms inhabiting adjacent mountains could be representatives of the same species with different pigment saturations, rather than competing species. The relationships between and within Atlapetes species are assessed based on mtDNA sequence data. Three main branches are demonstrated, comprising southern (Bolivian, northwest Argentinean), central (south and central Peruvian] and northern/western species. Clearly, the traditional groupings based on plumage colours did not demonstrate evolutionary trajectories in the genus. The data also show that many forms, currently ranked as subspecies, are genetically more divergent than sympatric species. Species rank is suggested for several forms hitherto treated as subspecies of geographically disjunct species.
Population dynamics of Black‐browed and Grey‐headed Albatrosses Diomedea melanophrys and D. chrysostoma at Campbell Island, New Zealand, 1942–96
Authors: Waugh Susan M. , Weimerskirch Henri , Moore Peter J. , Sagar Paul M.
Published: April 2008

The numbers of Black‐browed AlbatrossesDiomedea melanophrysand Grey‐headed AlbatrossesD. chrysostomaat Campbell Island, New Zealand, have declined dramatically since the 1940s. Black‐browed Albatross numbers went into a steep decline in the 1970s and, since at least 1984, have been increasing slightly at average rates of 1.1% and 2.1% per annum at two colonies. The long‐term downward trend in numbers of the Grey‐headed Albatross has continued into the 1990s, averaging annually between 3.0% and 4.8% per annum at different colonies. A demographic study carried out between 1984 and 1996 indicates that Black‐browed and Grey‐headed Albatrosses have similarly high annual adult survival rates (0.945 and 0.953, respectively). Black‐browed Albatrosses breed for the first time at a younger average age than do Grey‐headed Albatrosses (10 years and 13.5 years, respectively), have a higher average breeding success (0.663 compared with 0.397 for the latter species) and are annual breeders whereas Greyheaded Albatross show a typical biennial pattern of breeding. Both show low survival from fledging to first breeding; averaging 0.186 and 0.162 for Black‐browed and Grey‐headed Albatrosses, respectively. Both species are accidentally killed in the Japanese long‐line fishery for tunaThunnussp. in the Australasian region. The steep decline of Black‐browed Albatross numbers in the 1970s was concomitant with the development of this fishery in the foraging region of the Campbell Island birds. Currently, the slight increase in numbers is due to high adult survival rates and breeding success, and is coincident with a great reduction in long‐line fishing. With stable and high adult survival rates, it is expected that future population trends will be mainly influenced by the recruitment rates. The continuous decline in Grey‐headed Albatross numbers since the 1940s, before long‐line fishing developed in this region, indicates that natural environmental processes contributed to the downward trend in breeding numbers. Modelling indicates that Grey‐headed Albatross numbers will continue to decrease with the present demographic parameters. A comparison between the species breeding at different sites shows that differing environmental conditions influence demographic characteristics.
Annual variation in the timing of breeding and moulting in male and female Pied Flycatchers Ficedula hypoleuca
Authors: Hemborg Christer
Published: April 2008

During five breeding seasons, the timing of breeding and moulting was studied in the Pied Flycatcher Ficedula hypoleuca. In central Sweden, on average 67% of the males and 41% of the females started moulting before the young fledged. The proportion of individuals with an overlap between breeding and moulting varied considerably between years, with the highest proportion of moulting males being recorded in the year when the females started egg‐laying on the latest date. Despite a large annual variation in the proportion of individuals showing a moult/breeding overlap, the duration of this overlap varied insignificantly between years. The onset of moult in males seemed to be related to both calendar date and timing of the current breeding attempt. Most females postponed their moult until just before or just after the fledging of their young, independent of calendar date. There was no significant relationship between male and female moult scores and nestling weight at fledging or fledging success of their brood. Thus, in long‐distance migrants such as Pied Flycatchers, it may be adaptive to have some overlap between reproduction and moult, but there seems to be a limit to how early in the breeding cycle they are able to start moulting.
Geographical variation in the White‐tailed Tropicbird Phaethon lepturus, with the description of a new subspecies endemic to Europa Island, southern Mozambique Channel
Authors: Corre Matthieu Le , Cebc Pierre Jouventin
Published: April 2008

Geographical variation in measurements and colouration among populations and subspecies of White‐tailed Tropicbirds Phaethon lepturus, including birds from Europa Island (southern Mozambique Channel] was examined worldwide. Two groups were distinguished: the ‘large subspecies’(lepturus and fulvus from the Indian Ocean, catesbyi from the western Atlantic Ocean) and the ‘small subspecies’(ascensionis from the central and eastern Atlantic Ocean, dorotheae from the Pacific Ocean, and the birds from Europa Island). No clinal variation was found in the Indian Ocean, the birds from Europa Island being the only ‘small’ ones. This population also had a high frequency of golden morphs, a feature that does not exist elsewhere in the western Indian Ocean. These results indicate that Europa's population is isolated from all nearby colonies in the Indian Ocean, and does not belong to any of the two previously known subspecies of the area. It also differs from the birds of the two small subspecies by the frequency of the colour morphs and the distribution. Consequently, we propose to treat this population as a previously undescribed subspecies, endemic to Europa Island, for which we propose the name Phaethon lepturus europae. Geographical isolation of Europa Island and oceanic conditions in the Mozambique Channel are discussed to explain the isolation of this population.
Bird communities of dry forests and oak woodland of western Mexico
Authors: Pablo Corcuera M. Del R. , Butterfield Jennifer E.L
Published: April 2008

Bird species‐richness and densities were studied in spring and autumn of 1991 and 1992 in dry forest and oak woodland in western Mexico. Classification of the vegetation resulted in the identification of six dry forest types: from thorn forests, dominated byAcacia, through broad‐leaved tree forest (typical dry forest of western Mexico) and small‐leaved tree forest toIpomoeaforest. Oak woodland and mixed woodland, which are a transition between dry forest and the more mesic oak woodland, formed two further forest types. In the study area as a whole, bird densities were higher in autumn, following the rainy season, than in spring, which is the dry season, and the beginning of the breeding season. Densities in the two autumns were very similar (mean 93 ± 7.8 birds per 2.8 ha) but differed significantly between spring 1991 (57 ± 2.2 per 2.8 ha) and spring 1992 (70 ± 3.2 per 2.8 ha), possibly due to unseasonal rain in 1992. In autumn, bird densities were highest in thorn forests and lowest in broad‐leaved tree forests and oak woodland. In spring 1991, bird densities were highest inProsopisthorn forest and mixed woodland, and lowest in oak woodland. Bird species‐richness was low in oak woodland, in both seasons, and high in mixed woodland andIpomoeaforest in spring. Bird species composition between forest types was more similar in the spring than autumn. The spring similarity in species composition is explained by the presence of generalist species in times of food scarcity during the dry season, and by the homogeneity of the predominantly leafless vegetation. Comparison with the bird species composition of a dry forest in Venezuela and the Pacific coast of Mexico indicates that the sites in the present study have an intermediate number of species. Although the present study recorded a smaller number of bird species than on the Pacific coast, 16 were different, expanding the total for Mexican dry forest by 14% from 118 to 134.
Annual cycle of the Helmeted Honeyeater Lichenostomus melanops cassidix, a sedentary inhabitant of a predictable environment
Authors: Franklin Donald C. , Smales Ian J. , Quin Bruce R. , Menkhorst Peter W.
Published: April 2008

The annual cycle of breeding, moult and weight variation in the Helmeted HoneyeaterLichenostomus melanops cassidix, a sedentary bird of temperate southeast Australia, is documented. Breeding and moult were sequential unimodal annual events, whose timing was highly consistent between years. However, overlap of breeding and moult was frequent, and some individuals even commenced primary moult before laying their final clutch. The timing of the post‐juvenile moult was coincident with that of adults. Early‐hatched young moulted within a few months of hatching, but late‐hatched young deferred moult for a year. Helmeted Honeyeaters were heaviest in autumn and early winter, and lightest in spring and early summer, a cycle most consistent with the redirection of all available resources to reproduction. The long breeding season (seven‐and‐a‐half months) of the Helmeted Honeyeater, extensive overlap of breeding and moult, and other life‐history attributes including small clutch size, are more consistent with the described bio‐rhythmic patterns for birds in the humid tropics than the temperate zone. However, the Helmeted Honeyeater has a fairly rapid primary moult rate, unusual amongst species that overlap moult and breeding. This combination of attributes reflects the stable, somewhat seasonal environment occupied and the resource monopoly established by this tightly territorial subspecies. We speculate that extension of the breeding season, by overlapping breeding and moult, is one of the few options available to vary life‐history strategies amongst ‘old‐endemic’ Australian birds of the temperate zone.
Modelling habitat selection of Common Cranes Grus grus wintering in Portugal using multiple logistic regression
Authors: FRANCO ALDINA M.A. , BRITO JOSÉ C. , ALMEIDA JULIA
Published: April 2008

Predictive models of habitat suitability for the Common Crane Grus grus in a wintering area of southern Portugal were derived using logistic multiple regression and Geographic Information Systems. The study area was characterized by landscape variables and surveyed uniformly for the presence of cranes. The most important variables were distance to roosts, to open Holm Oak woods and to villages, and the occurrence of unpaved roads, shrubby vegetation, slope and orchards. Two models were built, the second having one variable fewer than the first. The selection of the best model was based on statistical and biological criteria. Crane distribution was negatively related to: distance to open Holm Oak Quercus rotundifolia woods and roosts. Additionally, unsuitable vegetation and orchard areas are avoided. In these areas movement is difficult, food availability is reduced and the risk of predation increased. We also found that villages and roads were avoided; disturbance is a significant factor for this species. Some management guidelines are proposed for the area: (1) maintenance of open Holm Oak woodlands, (2) incentives to avoid the abandonment of traditional agriculture and pastoral use of the area, which would lead to an increase of shrubby vegetation areas, (3) preservation of suitable roosting places and (4) management of new patches of forest and orchards.
Ingestion patterns and daily energy intake on a sugary diet: the Red Lory Eos bornea and the Malachite Sunbird Nectarinia famosa
Authors: DOWNS COLLEEN T.
Published: April 2008

This study examines whether nectarivorous birds regulate daily energy intake as proposed by Lloyd in 1991. Two Old World nectarivorous species, a large non‐passerine, the Red Lory Eos bornea, and a small passerine, the Malachite Sunbird Nectarinia famosa, were fed 0.25 mol/1 sucrose (9%), 0.73 mol/1 sucrose [24%] or 0.73 mol/1 glucose in separate laboratory trials to determine hourly and overall daily rate of sugar intake and consumption. Overall daily energy intake rates of the Malachite Sunbird and the Red Lory support the hypothesis of regulated energy intake for nectarivorous Old World birds. However, the species differ in their ingestion patterns through the day. The Red Lory ingests large volumes initially, regardless of sugar type. This is possibly a consequence of their large size and having a crop in which food can be stored. The Malachite Sunbird showed more regular hourly consumption through the day, and no change in mass during the day. Intake rates of both species were greater on lower sugar concentrations.
Vocalizations and relationships of Brown Creepers Certhia americana: a taxonomic mystery
Authors: BAPTISTA LUIS F. , KREBS ROBIN
Published: April 2008

Two taxa of creepers (Certhia spp.) occur in Europe, C. familiaris and its sibling species C. brachydactyla. The North American Brown Creeper was considered a close relative of C. brachydactyla by one author, a close relative of or conspecific with C familiaris by others, and more recently as a distinct species, C. americana, by the American Ornithologists' Union. Songs of these three creepers are comprised mostly of social calls which are derived from begging calls. Sequence of syllables (syntax) is very conservative in songs of European population of C. familiaris and C. brachydactyla. In contrast, syntax in songs of western North American C. americana is highly variable; however, syllable morphology and syntax in some populations or individuals within populations is remarkably similar to songs of C. brachydactyla, notably from France and Spain. Two social calls and sleeping behaviour of C. americana are also similar to those of C. brachydactyla. Either C. americana and C. brachydactyla are close relatives or they have characters retained from the ancestor common to all three species whereas those in extant C familiaris have diverged.