bluuebunny/crossref_metadata_2025 huggingface dataset:
Brood amalgamation in the Bristle‐thighed Curlew Numenius tahitiensis: process and function
Authors: LANCTOT R. B. , GILL R. E. , TIBBITTS T. L. , HANDEL C. M.
Published: April 2008

Alloparental care in birds generally involves nonbreeding adults that help at nests or breeding adults that help raise young in communal nests. A less often reported form involves the amalgamation of broods, where one or more adults care for young that are not their own. We observed this phenomenon among Bristle‐thighed Curlew Numenius tahitiensis broods in western Alaska during 1990–1992. Amalgamation of broods generally involved the formation of temporary and extended associations. Temporary associations were formed by the incidental convergence of broods soon after they left their nests. During this period, parents defended distinct brood‐rearing areas, were antagonistic to conspecifics and remained together for less than 3 days. Extended associations formed when chicks were 1–2 weeks old. Here, parents and their broods occupied distinct, but adjacent, brood‐rearing areas and moved around as a unit. Whether a brood participated in either temporary or extended associations or remained solitary appeared to depend on brood density in the immediate area and on hatching date. When chicks were 3–4 weeks old, aggregations of up to ten broods formed wherein young mixed and parents defended a common brood‐rearing area. All broods (n = 48) that survived to fledging joined such aggregations. Alloparental care involved only antipredator defence and was not associated with activities such as feeding and brooding. Most female parents abandoned their broods shortly after the young could fly and when aggregations were forming. The female parent of a pair always deserted its young before or on the same day as the male parent and, in every aggregation, one or two males continued to tend young for about 5 days longer than other male parents. In most cases, adults deserted the young 2–6 days before the young departed the area when about 38 days old. Bristle‐thighed Curlews also formed temporary associations with American and Pacific Golden Plover Pluvialis dominica and Pluvialis fulva, Whimbrel Numenius phaeopus, Bar‐tailed Godwit Limosa lapponica, Western Sandpiper Cal‐idris mauri and Long‐tailed Skua Stercorarius longicaudus. Curlews and other larger bodied species commonly attack‐mobbed predators together, whereas smaller bodied species generally gave alarm calls and circled the predators. For all species, the intensity of antipredator defence by attending adults gradually decreased as young became older and aggregations formed. We suggest that amalgamation of broods among Bristle‐thighed Curlew enhances predator defence, aids in the process of flock formation for migrating young, and allows females and some males to desert their young earlier.
Vocal communication in Peregrine Falcons Falco peregrinus during breeding
Authors: CARLIER P.
Published: April 2008

The wailing call and the creaking call of the Peregrine Falcon Falco peregrinus were quantified throughout the breeding period. The creaking call was given mainly during the courtship period by both males and females, and its frequency at this time did not differ significantly between sexes. From the start of incubation and thereafter, the creaking call was uttered more frequently by males than by females; during the nestling period, it was mostly related to the male's transfer of food. The wailing call frequency never differed significantly between males and females and increased during the nestling period. This call was less linked with the presence of the mate than was the creaking call.
Incubation temperature in the Australasian Gannet Moms senator
Authors: EVANS ROGER M.
Published: April 2008

Gannets (Sulidae) and some other pelecaniforms incubate their eggs under the webs of their totipalmate feet. These species have a wide latitudinal distribution from tropics to subarctic, but little is known of the incubation temperatures attained. I measured egg temperatures of the Australasian Gannet Morns serrator at Cape Kidnappers, New Zealand, employing a data logger to obtain records every 15 min for day‐long sample periods at undisturbed nests. Egg surface temperatures were relatively stable and little affected by ambient temperature. Mean surface temperature of natural eggs was 34.9oC for samples taken during the first 4 days of incubation, but this then increased and stabilized at 36.5oC. Internal temperature of pipped eggs was about 1oC higher, attributable to embryonic heat production. Upper surface temperature of eggs kept in a fixed position was about 2oC below deep adult body temperature (40.3oC), suggesting heat is transferred directly from the body through the feet. Clutch size does not appear to be limited by an inability to warm two eggs. These results are in general agreement with measurements from other web incubators and are well within the range for species with conventional brood patch incubation.
Incubation and brooding performance of the Antarctic Petrel Thalassoica antarctica at Svarthamaren, Dronning Maud Land
Authors: LORENTSEN SVEIN‐HÅKON , RØV NILS
Published: April 2008

Antarctic Petrel Thalassoica antarctica incubation and brooding effort was studied at Svarthamaren, Dronning Maud Land, during the austral summer of 1991–1992. The females probably left the nest site shortly after egg laying. The duration of incubation and brooding shifts as well as the daily weight loss (absolute and proportionate) were comparable with those of other similar‐sized procellariform species. Males spent more time incubating and brooding than did females, suggesting higher female energy stress due to egg laying. Incubating birds which were below average weight were likely to desert the nests before their mates returned from feeding trips. Both males and females lost approximately one‐fifth of their body‐weight during their first incubation shifts. Nevertheless, they increased their initial weights from egg laying to hatching and had their highest initial weights when they returned to start the shift during which the egg hatched. No factors related to adult body‐weight explained the duration of the incubation shifts. Both males and females gained weight at a higher rate when at sea than they lost it during incubation, and it is suggested that factors unrelated to food availability or individual feeding skills may be important in regulating the duration of the incubation shifts and the stay at sea.
Influence of reproductive success on breeding frequency in four southern petrels
Authors: CHASTEL OLIVIER
Published: April 2008

Patterns of breeding frequency of White‐headed Pterodroma lessoni, Great‐winged Pterodroma macroptera, White‐chinned Procellaria aequinoctialis and Grey Petrels Proceharia cinerea have been studied at Kerguelen and Crozet Islands. The White‐headed Petrel (summer breeder) followed an essentially biennial cycle with only 13% of successful individuals breeding again the next year. On the other hand, the Great‐winged Petrel (winter breeder) was mainly an annual breeder with 78% of successful birds breeding again the next year. Both White‐chinned (summer breeder) and Grey Petrels (winter breeder) showed a higher breeding frequency than Pterodroma species, with 91% and 93%, respectively, of successful birds returning to breed the following season. These contrasting patterns may be related to the timing of energetic constraints encountered during the interbreeding period, principally the moult and the restoration of breeding condition. It is suggested that these post‐breeding constraints are more marked in winter and in oceanic waters, leading to breeding frequencies being lower than in summer and in neritic waters. The intermediate patterns of breeding frequency found in the Great‐winged Petrel (mainly annual) and the White‐headed Petrel (mainly biennial) show that among Procellariiformes there is a continuum between annual and strictly biennial species.
Digestive efficiency of the Hoatzin, Opisthocomus hoazin: a folivorous bird with foregut fermentation
Authors: GRAJAL ALEJANDRO
Published: April 2008

The Hoatzin Opisthocomus hoazin is the only known bird with a well‐developed foregut plant fermentation system; most fermentation takes place in the crop and caudal oesophagus. To test Hoatzin digestive efficiency, balance (total collection) trials with captive Hoatzins were made using two experimental diets of different composition and fibre content. Dry matter (DM) intakes were similar for the diets (mean = 62.8 g DM/kg body mass/ day). Average DM, organic matter and nitrogen digestibilities were not significantly different between diets, with average values of 72.9%, 75.0% and 78.3%, respectively. In vitro organic matter digestibilities by cow ruminal inoculum were very similar to organic matter digestibilities in live Hoatzins for both diets. Fibre digestibility was among the highest recorded for herbivorous birds. Cellulose and acid detergent fibre digestibilities were 58.8% and 52.7%, respectively. Neutral detergent fibre (NDF) digestibility differed among diets—the higher the NDF content of the diet, the higher the NDF digestibility. The NDF digestibilities were 37.9% and 70.9% for the two diets with NDF concentrations of 32.4% and 37.3%, respectively. Differences in NDF digestibility can be attributed to the different concentrations of hemicellulose in the experimental diets. The high overall digestibility by captive Hoatzins is higher than values previously reported for other avian herbivores but similar to those of foregut‐fermenting mammals on similar diets. The unique digestive strategy of the Hoatzin maximizes digestion of cell wall and cell contents. The high digestive efficiency in the Hoatzin is not predicted by allometric models of fibre digestion as a function of body mass. Other nutritional benefits, such as detoxification of plant secondary compounds and microbial synthesis of essential amino acids and vitamins, may explain the evolution of foregut fermentation in this avian folivore.
Modelling animal populations in changing landscapes
Authors: PULLIAM H. RONALD , LIU JIANGUO , DUNNING JOHN B. , STEWART DAVID J. , BISHOP T. DALE
Published: April 2008

Models of Mobile Animal Populations (MAP models) simulate long‐term land use changes, population trends and patterns of biological diversity on landscapes of 103‐105 ha. MAP models can incorporate information about past land‐use patterns and management practices and can project future patterns based on management plans. We illustrate this approach with an example of how implementation of a U.S. Forest Service management plan at the Savannah River Site in South Carolina, U.S.A., might influence population trends of Bachman's Sparrow Aimophila aestivalis, a relatively rare and declining species in southeastern pine forests. In this case, a management plan, largely designed to improve conditions for an endangered species, Red‐cockaded Woodpecker Picoides borealis, may have a negative impact, at least in the short term, on another species of management concern, Bachman's Sparrow.

In a parallel processing version of the MAP models, a single landscape that would ordinarily be too large or detailed to be simulated on a single computer is subdivided into a number of smaller landscapes, and each landscape is simulated in parallel, either on a single multi‐tasking machine or on a group of networked machines. With this approach we are attempting to determine just how large a landscape must be before the dynamics of a population within it are more or less independent of factors beyond the landscape boundaries.
The landscape ecological approach in bird conservation: integrating the metapopulation concept into spatial planning
Authors: OPDAM PAUL , FOPPEN RUUD , REIJNEN RIEN , SCHOTMAN ALEX
Published: April 2008

In The Netherlands, fragmentation of (semi)natural ecosystems is regarded as a major nature conservation problem. The current Dutch Nature Conservation Policy Plan proposes a spatial network consisting of existing nature reserves, nature redevelopment areas and corridor zones. One of the objectives is to stop the assumed decline of biodiversity due to fragmentation. In this contribution we show that breeding birds are affected by the spatial distribution of their habitat. We also show how problems due to fragmentation can be solved by integrating landscape ecological research data Into planning procedures. Fragmented bird populations show metapopulation characteristics, dependent on the degree of fragmentation. This can be concluded from pattern studies, in which presence or absence patterns are correlated with spatial characteristics. Metapopulation dynamics were used, and the frequency of local extinction and of recolonization were related to size of habitat patches and spatial position in the landscape. The conclusion is that, depending on the spatial scale, landscape fragmentation is a threat to birds. On the basis of empirical data, statistical and metapopulation models are being developed to be used to evaluate spatial planning scenarios and to support decision making about which scenario is closest to the planning aims.
The restoration of the Mauritius Kestrel Falco punctatus population
Authors: JONES CARL G. , HECK WILLARD , LEWIS RICHARD E. , MUNGROO YOUSOOF , SLADE GLENN , CADE TOM
Published: April 2008

By 1974, the Mauritius Kestrel Falco punctatus had declined to only four known wild birds, including one breeding pair, as a result of habitat loss and pesticide contamination. A conservation project begun in 1973 has used many management techniques including captive breeding, supplemental feeding of wild birds, provision of nestboxes, multiple clutching, egg pulling, artificial incubation, hand rearing and release of captive‐bred and captive‐reared birds by hacking, fostering and predator control. A total of 331 kestrels were released in the 10 years up to the end of the 1993–1994 breeding season; one‐third of these were captive bred, the rest were derived from eggs harvested from the wild. About 257 (78%) released birds survived to independence and 61% of independent juveniles survived their first winter. Although at least 71% of ringed birds attempted to breed in their first year, only 38% of the nests of first‐year females successfully fledged young, averaging 1.7 per successful nest. Older females fledged young from 64% of nests, fledging an average of 2.0 per successful nest. The breeding success of hacked birds was similar to that of parent‐raised kestrels, though the clutches of hacked birds tended to be larger. Annual replacement of birds holding territories averaged 17% for both sexes. By the 1993–1994 season, an estimated 56–68 pairs had established territories in the wild with a post‐breeding population, including floating birds and independent young, of 222–286. Most of the kestrels were in three sub‐populations, two of which were derived entirely from released birds. Mauritius Kestrels are relatively sedentary; 89% of ringed birds found nesting were less than 5 km from their release or Hedging site. Since the pesticides responsible for their decline are no longer used, the number of Mauritius Kestrels should continue to rise through natural recruitment. The distribution of suitable habitat suggests that an eventual population of 500–600 kestrels on Mauritius is possible. Due to its outstanding success, the release programme for the Mauritius Kestrel ended after the 1993–1994 breeding season, though the population will continue to be monitored carefully for at least the next 5 years.
The North American Waterfowl Management Plan and Wetlands for the Americas programmes: a summary
Authors: PATTERSON JAMES H.
Published: April 2008

Bird conservation is a global environmental issue which requires innovative approaches to species and habitat protection and management and the promotion of sustainable development practices. This paper presents some of the highlights in the evolution of two programmes, what may or may not have made them succeed, what lessons were learned and what recommendations can be made for the future of bird conservation. The evolution of the North American Waterfowl Management Plan (NAWMP) and Wetlands for the Americas (WA) bears a lot of similarity to the evolution of International Waterfowl and Wetlands Research Bureau and Ramsar.
Revising the British Red Data List for birds: the biological basis of U.K. conservation priorities
Authors: AVERY MARK , GIBBONS DAVID WINGFIELD , PORTER RICHARD , TEW TOM , TUCKER GRAHAM , WILLIAMS GWYN
Published: April 2008

The list of British Red Data birds (Batten et al. 1990) includes 117 species, 109 of which qualified on one or more quantitative criteria referring to rarity, localized distribution, population decline and international importance. A wealth of data on bird population levels and trends in the United Kingdom and Europe has recently become available, allowing refinement and improvement of the criteria for qualification. Here we propose that in assigning priorities for conservation action in the U.K. (Britain and Northern Ireland), three biological axes need to be considered: national threat (measured as rarity, localized distribution and population decline in the U.K.), international importance (the proportion of the European population in the U.K.) and international threat (European/global conservation status). Only the first two of these axes were considered by Batten et al. (1990). Each of these axes has been sub‐divided into high, medium and low categories using quantitative thresholds, and from this we produce a national ‘conservation cube’ (three axes, each with three categories and thus 27 cells). Data permitting, every species in the U.K. can be allocated to one of these cells. We suggest that species high on either (or both) of the national or international threat axes be considered as species of high conservation priority (the red list) and that among the remainder those that rank at least medium on one of the axes be considered as of medium conservation priority (the amber list). All other species are of low conservation priority (the green list). We suggest that this three‐axis model could be applicable to other taxa and countries.
Extinction risk assessment for birds through quantitative criteria
Authors: MACE GEORGINA M. , COLLAR N. J.
Published: April 2008

The system used for classifying species according to their risk of extinction in international Red Lists is currently being revised by the International Union for Conservation of Nature. The proposed system is based around a set of quantitative criteria and aims to provide a more explicit and objective method that can be applied across a wide variety of living forms. The first major application has been in the preparation of a new edition of Birds to Watch, a summary of threatened bird species at a global level, by BirdLife International. An analysis of the classification of bird species in this publication indicates that the proportion of birds thought to be threatened varies across regions from about 14% in New Zealand and 12% in Africa down to only 3% in Europe. There are some significant differences among regions in the kinds of criteria that lead to threatened listing, with continuing or expected declines in numbers or habitat being especially significant in Africa and Europe.
Population dynamics of the Grey Partridge Perdix perdix 1793–1993: monitoring, modelling and management
Authors: POTTS G. R. , AEBISCHER NICHOLAS J.
Published: April 2008

The longest available bag record of Grey Partridges Perdix perdix in Great Britain (1793–1993) reveals a collapse of stocks after 1952 despite considerable annual variation. The annual fluctuations were attributable largely to annual variations in chick survival rate. The Game Conservancy Trust's National Game Census revealed that chick survival rates averaged 49% before the introduction of herbicides and 32% once their use became widespread. On a study area in Sussex, where spring density declined from around 21 pairs per km2 in 1968 to under four pairs per km2 in 1993, annual chick survival rates averaged 28% with no demonstrable trend. The annual over‐winter “survival” rates in the area improved during 1968–1993, whereas brood production rates declined. Simulation modelling showed that a reduction in chick survival rate from 49% to 32% had little effect on spring stocks as long as nest predation was controlled but that stocks collapsed when nest predation control was relaxed. The effect of such a change in chick survival rate on population status was investigated by reference to 36 other studies in the literature. Amongst 20 studied populations which were stable, adjusting mean chick survival rates downwards produced demographic parameters characteristic of declining populations in all but two cases. Conversely, adjusting chick survival rates upwards for 16 declining populations made all but two stable. Diagnosing and remedying the causes of population change require a testable understanding of density‐dependent factors and compensatory processes, best approached by a combination of monitoring, modelling and management.
The response of bird populations to habitat loss
Authors: DOLMAN PAUL M. , SUTHERLAND WILLIAM J.
Published: April 2008

Environmental change through altered climate and land use could have a severe impact on bird populations. Predicting the consequences for the size of bird populations is one of the crucial problems for their conservation. We show how a population model based on the behaviour of individuals can be used to predict the consequences of habitat loss. For a wide range of conditions, loss of either wintering or breeding habitat results in population reduction. The approach is then extended to consider the impact of habitat loss in the wintering area on bird species with complex migratory systems. This shows that ‘knock‐on’ effects may occur, so that habitat loss in a wintering area may affect populations which did not initially use that area. The ability to alter migration routes in response to environmental change may be crucial to the future viability of populations. Using a simple model combining genetics and population dynamics, we show that aspects of the biology of a species may affect whether or not its migration strategy is flexible enough to shift in response to habitat change. Some species may be able to adopt new migration routes and avoid the catastrophic consequences of habitat loss in traditional wintering areas; however, other species may lack this flexibility and may suffer severe population declines as a consequence.
Consequences of habitat loss and change to populations of wintering migratory birds: predicting the local and global effects from studies of individuals
Authors: GOSS‐CUSTARD JOHN D. , CALDOW RICHARD W. G. , CLARKE RALPH T. , DURELL SARAH E. A. LE V. DIT , URFI JAMIL , WEST Y D.
Published: April 2008

Population models show that the response of migratory bird populations to a reduction in the area, or change in the quality, of their winter feeding areas depends critically on the shape (linear or non‐linear) and strength (slope) of the relationship describing how the proportion dying from starvation changes with population density. Yet the parameters that define such density‐dependent functions are extremely difficult to estimate from direct measurements of mortality at different population sizes. Even if they could be estimated, there would be uncertainty as to whether or not the relationship would remain the same, and thus provide reliable predictions, in the new circumstances for which forecasts are required. This paper summarizes studies of the Oystercatcher Haematopus ostralegus which aim to derive the shape and strength of the winter density‐dependent mortality and emigration function for one estuary, under existing and new circumstances, from the responses of individual birds to each other and to their spatially and seasonally varying food supply. Based on these studies, an individuals‐based, physiologically structured game theoretic distribution model has been built which predicts the carrying capacity and numbers of birds dying at different population sizes. The model also can be applied to Oyster‐catchers occupying several estuaries distributed throughout their wintering range and can thus be extended to the entire biogeographical or global population. In addition, it can be used to identify some easily measured behavioural and ecological parameters that identify those species, from a wide range of taxa, that are most likely to be affected by habitat loss and change.
Buzzards Buteo buteo and Ravens Corvus corax in the uplands of Britain: limits to distribution and abundance
Authors: GIBBONS DAVID , GATES SIMON , GREEN RHYS E. , FULLER ROBERT J. , FULLER ROBIN M.
Published: April 2008

The current breeding ranges of Buzzards Buteo buteo and Ravens Corvus corax in Britain are restricted to the west, and both are relics of former widespread but not necessarily even distributions. Moore (1957) attributed the Buzzard's contraction in range to persecution by gamekeepers, his evidence being the complementary nature of the Buzzard's distribution with those of gamekeepers in the lowlands and grouse moors in the uplands; others have attributed the Raven's decline to the same cause. Is Moore correct and, if so, are these species' ranges still limited by persecution? Here we adopt an approach similar to Moore's, whereby we compare the current geographical patterns of abundance of Buzzards and Ravens in the British uplands with that of an index of grouse moor density. Unlike Moore, however, we take into account climate, land cover, topography and sheep stocking density, as well as grouse moor distribution, using multiple logistic regression modelling. We show that in the uplands the distribution of grouse moors strongly limits that of Buzzards and Ravens but are unable to conclude that this is a result of persecution because there are several competing hypotheses (moor management, food and nest‐site availability) between which we are unable to distinguish.
Disease and the abundance and distribution of bird populations: a summary
Authors: MAY ROBERT M.
Published: April 2008

Over the past few years, I have written several reviews about the effects of infectious diseases upon the distribution and abundance of their host populations. One general review and synthesis is in the fmd chapter of a book whose earlier chapters focus mainly on human diseases (Anderson & May 1991). A bird‐specific discussion, with particular reference to conservation issues, is given by Dobson and May (1991). Broadly related questions about the invasion, persistence and spread of infectious diseases within animal communities are explored by Anderson and May (1986) and with emphasis on bird populations by Dobson and May (1986). Also relevant are a set of papers from the Society for Conservation Biology's first‐ever symposium on Conservation and Disease (for an overview, see May 1988, Scott 1988).

Rather than burdening the literature with a recapitulation of these existing reviews, this paper gives a sign‐posted guide for those who are not familiar with this particular literature. I first sketch reasons for believing that infectious diseases play an important part in the life history of birds. Next I point towards an analytic framework for understanding the dynamics of host‐pathogen associations. Finally I list some of the implications for the conservation biology of bird populations.
Bird calls: just emotional displays or something more?
Authors: MARLER PETER , EVANS CHRISTOPHER
Published: April 2008

Two widely held assumptions about the sounds of birds and other animals are (1) they are impulsive and involuntary, and cannot be controlled, and (2) they are based only on emotion, apparently because the stimuli eliciting them are thought to be very generalized. The validity of these assumptions has been tested in studies of the alarm calling and food calling behavior of domestic chickens. Videotapes of aerial and ground predators–a hawk overhead and a raccoon on the ground–were effective in eliciting the two major classes of alarm calls. The frequency of aerial alarm calling was strongly affected by presence or absence of a companion, while other aspects of antipredator behavior were unchanged. This so‐called “audience effect” on calling is not found with the ground predator call, apparently because this call is addressed to the predator as well as companions. The rules for audience effects are different again with food calling. Evidently calling is not completely impulsive, but can be controlled. By varying the attributes of digitized video images of predators we have shown that stimuli eliciting the aerial predator alarm call are quite specific, encoding different information than the ground predator call. Playback experiments demonstrate that another chicken can decode this information, and react adaptively. Although emotion is undoubtedly involved in bird calling, we conclude that simple emotion‐based models of bird calls are inadequate as the sole basis for explaining the vocal behavior of birds.
Immunocompetence, mast cells and sexual behaviour
Authors: SILVER RAE , ZHUANG XIAOXI , SILVERMAN ANN‐JUDITH
Published: April 2008

This paper reports a provocative and novel observation. Specifically, we have shown that in Ring Doves Streptopelia roseogrisea, following a brief period of courtship, cells of the immune system–mast cells–appear in the brain. This is surprising in that it has long been thought that the blood‐brain barrier prevents the movement of blood‐borne cells into the parenchyma (neural tissue) of the brain. The conditions under which these cells appear, their chemical and ultrastructural features and their potential in neuroendocrine signalling functions are discussed. The significance of these cells for the expression of behaviour and their specific role in the medial habenula (the brain area to which they migrate) remain to be explored. While our research has focused on a domesticated, laboratory bird species, the relationship between sexual behaviour and immunocompetence has long been of interest in field work and in studies on the evolution of sexual behaviour. It is hoped that this work, now in its infancy, will bridge field and laboratory, as well as providing a forum for integrating mechanistic and evolutionary concepts in neuro‐immuno‐endocrinology.
The cost of secondary sexual characters and the evolution of cost‐reducing traits
Authors: MØLLER ANDERS PAPE
Published: April 2008

Secondary sexual traits are characterized by their exaggerated expression relative to homologous nonsexual characters in other species. All models of sexual selection assume that sex traits are costly to produce and maintain, and individuals with reduced costs of production and maintenance of secondary sexual characters would be at a selective advantage. A number of morphological, physiological and behavioural traits may have evolved as a result of their cost‐reducing properties: (1) body size, which does not change throughout life, that allows certain individuals to develop exaggerated sex traits, (2) cost‐reducing traits, such as muscle size, that improve with practice and (3) actual cost‐reducing traits, such as wing size in birds with song flight, which are produced in advance of or simultaneously with the sex trait. Cost‐reducing traits may coevolve with secondary sexual characters and allow more extreme sexual signalling than would otherwise have been possible in their absence or in reduced versions.
A new genus and species of passerine from the eastern rain forest of Madagascar
Authors: GOODMAN STEVEN M. , LANGRAND OLIVIER , WHITNEY BRET M.
Published: April 2008

Cryptosylvicola randrianasoloi is described as a new genus and species in the family Sylviidae. This bird is endemic to the rain forests of eastern Madagascar, where it is restricted to elevations between 900 and 2100 m a.s.l. Cryptosylvicola randrianasoloi is distinguished from other Malagasy, African and Asian taxa by plumage colouration, external morphological characters and voice. The discovery of this new taxon in several well‐known areas of Madagascar, and the fact that it has a relatively broad distribution in that country, indicates that much still remains to be learned about the biota of the island.
Wintering site fidelity and movement patterns of Western Sandpipers Calidris mauri in the San Francisco Bay estuary
Authors: WARNOCK SARAH E. , TAKEKAWA JOHN Y.
Published: April 2008

Western Sandpipers Calidris mauri are the most numerous shorebird species in the San Francisco Bay estuary during winter. A sample of 106 Western Sandpipers was captured in mist nets and radio‐marked with 1‐g transmitters to examine their wintering site fidelity and movements. Differences in distances moved, home range extent and core area size were examined by age, sex, season, site, time of day and tide. All birds remained in the south San Francisco Bay region during winter and exhibited strong site fidelity, with a mean home range of 22.0 km2 or only 8% of the study area. First‐year birds had larger home ranges (26.6 ± 3.6 km2) than adults (17.2 ± 2.5 km2) in winter, but home range sizes of males and females were not significantly different in any period. Home range sizes were similar between seasons, but core areas were smaller in spring (6.3 ± 1.2 km2) than in early (9.6 ± 4.0 km2) or late (11.6 ± 1.6 km2) winter. Movements and home range size were similar for radio‐marked birds located during day and night. The high degree of regional and local site fidelity demonstrated that the mixture of natural mud fiats and artificial salt ponds in southern San Francisco Bay provided sufficient resources for large wintering populations of Western Sandpipers.
Timing of breeding in Black Grouse Tetrao tetrix and Capercaillie Tetrao urogallus and distribution of insect food for the chicks
Authors: BAINES D. , WILSON I. A. , BEELEY G.
Published: April 2008

In Perthshire (Scotland), Black Grouse Tetrao tetrix broods less than 3 weeks old preferred herb‐rich grassy flushes with Bog Myrtle Myrica gale, whereas in the northern Pennines (England), all broods were found on grass‐dominated moorland or enclosed rough grazing habitats chiefly of grass and rushes. In both areas, broods used habitats with taller vegetation that had more invertebrates, particularly moth caterpillars and sawfly larvae (Sym‐phyta, Hymenoptera). Within preferred habitats, broods were found in vegetation containing more flies (Diptera), plant bugs (Hemiptera) and ichneumon flies (Hymenoptera) than at randomly chosen sites. The main hatch of Black Grouse chicks in Perthshire coincided with the peak availability of moth caterpillars preferred by chicks. Broods in the Pennines hatched 1 week later than those in Scotland, and this later breeding in the south may be an adaptation to utilize the later peak biomass of sawfly larvae, the chief insect prey there. Data collected for Capercaillie Tetrao urogallus suggest a similar degree of synchronization between their peak hatch and the availability of moth caterpillars on Bilberry Vaccinium myrtillus.
Egg‐size variation and reproductive success in the Herring Gull Lams argentatus: adaptive or constrained size of the last egg?
Authors: KILPI MIKAEL , HILLSTROM LARS , LINDSTROM KAI
Published: April 2008

Herring Gull Larus argentatus eggs from a study colony in the Baltic showed a slight but significant variation in egg size within the laying sequence. Last‐laid eggs were only about 5% smaller by volume than first eggs. There was no significant difference in dry yolk weight or dry albumen weight, although possible differences were evident. The chicks had nearly equal hatching weights and equally long tarsi. There was no differential mortality in the third chick in the study colony, and there were no indications of egg‐size‐mediated mortality. The birds in the colony produced an average of 1.45 fledglings per pair. Compared with several other studied colonies, the difference in egg size within a clutch was low, and a comparison of colonies from northwestern Europe suggests that variance within the clutch is negatively correlated with fledging success, so that a large difference in size between first and last eggs is associated with low fledging success. We suggest that the size of the last egg in the clutch reflects the feeding potential in the environment and is mainly a nonadaptive response to poor feeding conditions during laying.
Post‐release survival of oiled, cleaned seabirds in North America
Authors: SHARP BRIAN E.
Published: April 2008

The number of days between ringing and recovery of oiled, cleaned and released seabirds was extremely low, usually a matter of a few days or weeks, and for three species was 5–100 times lower than for non‐oiled birds. For oiled, cleaned Guillemots Una aalge, postrelease life expectancy was 9.6 days and long‐term recovery rates were 10–20% of those of non‐oiled birds. Measures of survival were not greater for oiled birds treated in recent years with modern methods. The cost and effectiveness of rehabilitation efforts for oiled seabirds need to be reexamined in the light of results showing low post‐release survival.
Brood size manipulations in Great Horned Owls Bubo virginianus: are predators food limited at the peak of prey cycles?
Authors: ROHNER CHRISTOPH , SMITH JAMES N. M.
Published: April 2008

The reproduction of raptors strongly depends on food resources. It is unclear whether predators experience superabundant food during cyclic peaks of prey populations. In order to test this hypothesis, four pairs of Great Horned OwlsBubo virginianuswith two young were subjected to brood size manipulations during high densities of cyclic Snowshoe HareLepus americanuspopulations in southwestern Yukon, Canada. Broods older than 35 days were temporarily enlarged by one, and then by two, young. No effects were observed when one owlet was added, but the addition of two young resulted in significant weight losses in manipulated broods. Females with enlarged broods moved farther from their nest sites at night, presumably reflecting increased hunting effort, and also spent less time near the nest during the day. Food additions to enlarged broods returned the parental behaviour to normal. We conclude that these large predators did not experience superabundant food at this stage of the breeding season during a peak in cyclic prey.
Seasonal patterns of food storing in the Jay Garrulus glandarius
Authors: CLAYTON N. S. , MELLOR R. , JACKSON A.
Published: April 2008

This study investigated seasonal patterns in food consumption and food storage in six captive Jays Garrulus glandarius. In the first experiment, seasonal changes in food‐storing intensity were tested by presenting acorns (oak seeds, Quercus spp.) in spring, summer and autumn. There were no significant differences between the seasons in the amount of food eaten. However, significantly more food was taken and stored in the autumn than in the spring and summer months. In the spring and summer, the acorns were stored between the doorframes, on the ledges of the aviaries and under the bark of branches. In the autumn, Jays also began to hoard underneath the plastic sheeting covering the hard‐board flooring by ripping the polythene to create a hidden cache site. The length of time over which the stored food was left before retrieval increased from summer to autumn. Food storing also occurred in spring and summer but was short term. The second experiment tested whether or not there were seasonal changes in food preference by presenting birds with acorns, peanuts and mealworms in the summer and autumn. More peanuts were eaten, taken and stored in the autumn than in the summer, and, as in the first experiment, significantly more acorns were taken and stored in the autumn. In the autumn, only a few mealworms were eaten before the birds stored acorns and peanuts, whereas in the summer, birds tended to eat most of the mealworms before they began to store. As in the first experiment, items tended to be buried in the ground in the autumn and left for longer periods before retrieval. These results are discussed in relation to the demand that each food type places on the Jay's time.
The reproductive success of Blackbirds Turdus merula in relation to habitat structure and choice of nest site
Authors: HATCHWELL B. J. , CHAMBERLAIN D. E. , PERRINS C. M.
Published: April 2008

The reproductive success of a population of Blackbirds Turdus merula occupying farmland and woodland was studied over 3 years to investigate the effects of habitat on breeding success. Territory distribution was patchy in both farmland and woodland; some areas were unoccupied, while other areas were occupied at variable densities. Habitat structure appeared to influence occupation: the index of habitat complexity (“cover score”) was higher in occupied areas than in unoccupied areas and high‐density territories had higher cover scores than low‐density territories. However, habitat structure had no significant effect on reproductive success because the cover scores of territories where pairs were successful did not differ significantly from those of territories where there were no successful breeding attempts. There was no evidence of differential mortality rates in adults according to habitat. The height, bulk and exposure of c. 430 nests were measured to determine the effect of nest and nest‐site characteristics on reproductive success. Nest exposure was the only feature that differed between successful and failed nests, successful nests being less exposed than failed nests. The major cause of breeding failure was nest predation, but the effect of nest exposure operated only during the laying and incubation period and not during the nestling period. The significance of habitat structure for variation in population densities between habitats is discussed.
The phylogenetic relationships of Berthelot's Pipit Anthus berthelotii illustrated by DNA sequence data, with remarks on the genetic distance between Rock and Water Pipits Anthus spinoletta
Authors: ARCTANDER PETER , FOLMER OLE , FJELDSÅ JON
Published: April 2008

The phylogenetic relationships of Berthelot's Pipit Anthus berthelotii, which is endemic to three groups of North Atlantic islands, have puzzled ornithologists for more than a century. A total of 1041 base pair cytochrome b mitochondrial DNA sequences from Berthelot's Pipit are compared with homologous sequences from the Tawny Pipit Anthus campestris, Richard's Pipit Anthus novaeseelandiae, the Meadow Pipit Anthus pratensis, the Red‐breasted Pipit Anthus cervinus, the Tree Pipit Anthus trivialis, Rock and Water Pipits Anthus spinoletta and the White Wagtail Motacilla alba. In the resulting phytogeny, the sister taxon of Berthelot's Pipit is unambiguously the Tawny Pipit, with Richard's Pipit forming a deeper branch on the same clade. Sequences of a Danish Rock Pipit and a Swiss Water Pipit support a close relationship between these two species, but more comprehensive studies of intra‐ and interpopulation variation are required before considering their taxonomic ranking. Some preliminary inferences are made regarding phylogenetic tendencies in the genus Anthus.
Comparative foraging ecology of Madagascar vangids (Vangidae)
Authors: YAMAGISHI SATOSHI , EGUCHI KAZUHIRO
Published: April 2008

The Vangidae, an endemic family in Madagascar, contains 14 species in 11 genera. The foraging behaviour of 13 species of vangids was investigated during the periods August‐November 1989 and September‐November 1990. These vangids are grouped into six bill types according to their bill shape, using the analogy of gripping tools: (1) forceps. (2) radio pliers, (3) strong pinchers, (4) pliers, (5) standard and (6) flat forceps types. We recognized seven foraging niches: (A) canopy‐gleaning, (B) general, (C) ground‐snatching, (D) trunk/ branch‐probing, (E) leaf and twig/branch‐gleaning/probing, (F) leaf and twig/branch‐gleaning and (G) trunk‐gleaning niches. Two or more coexisting species with the same foraging niche differed in their bill types. Those vangids that exploited similar resources segregated in their bill types, geographic ranges and/or foraging niches, presumably to avoid severe competition. Several vangid species partially occupied the ecological niche that would be filled by woodpeckers elsewhere.
Nocturnal feeding by Dark‐bellied Brent Geese Branta bernicla bernicla
Authors: LANE SIMON J. , HASSALL MARK
Published: April 2008

The occurrence and extent of nighttime feeding by Dark‐bellied Brent Geese Branta bernicla bernicla on salt marshes adjacent to their tidal roost site were assessed on the north Norfolk coast using position‐sensitive radio transmitters. Nine birds were monitored on 143 bird‐nights, and feeding was recorded on 87. The frequency of feeding by night varied widely between individuals. The mean proportion of the night spent feeding for one bird was 19.7 ± 8%. Of this, 59% occurred within ± 1.5 h of high tide. Neither the proportion of the whole night spent feeding nor the intensity of feeding around high tide varied with the length of the night or with time after sunset at which high tide occurred. The extent of nocturnal feeding was also independent of the brightness and duration of moonlight. The birds fed for significantly longer on colder nights, and there was a significant positive relationship between the proportion of the night spent feeding and maximum temperature the preceding day. Analysis of daytime activity budgets on inland pastures showed that the proportion of time engaged in nonfeeding, energy‐expensive activities was also positively related to maximum daytime temperature. Increases in the proportion of the night spent feeding after warmer days were achieved by increasing the period of time spent feeding on either side of the high tide, not by increasing feeding intensity at high tide. It is concluded that the geese compensate for increased energy expenditure during the day by increasing the extent to which they feed at night. Implications of increasing energy expenditure as a result of disturbance during the day are discussed.
Diurnal cycles in microhabitat use by forest passerines: consequences for community structure
Authors: VILA CARLES , RODRIGUEZ‐TEIJEIRO J. DOMINGO , OLIVA FRANCESC
Published: April 2008

Time of day is usually not considered an important factor underlying the structure of forest passerine communities. However, this study shows that the positions exploited in trees by some members of a community change during the day in a cyclic pattern. Coal Tit Pants ater, Crested Tit Parus cristatus and Goldcrest Regulus regulus foraged lower and nearer to the trunk at midday than in the first and last hours of the day. Simultanously, there were diurnal changes in the niche breadth (degree of uniformity in the exploitation of the different parts of the trees). The Coal Tit reached the maximum niche breadth values during the central part of the day, with the minimum being recorded at that time for the Crested Tit and the Goldcrest. On the other hand, Treecreepers Certhia sp. did not show significant diurnal variation. These results, together with the changes in activity levels during the day for each species, suggest that time of day plays an important role in the structure of the community, allowing a more uniform use of the habitat and addressing a new interpretation of the interspeciic relationships inside the community, with competitive relationships not showing the same intensity throughout the day.