Showing papers in "Bird Study in 2003"
TL;DR: Extensive long-term monitoring schemes, such as the NRS, that collate large historical data sets will become increasingly valuable for monitoring the impact of environmental change.
Abstract: Capsule A review of its methodology, analytical procedures and uses. Aims To provide a comprehensive review of the UK Nest Record Scheme (NRS), its methodology and value to science and conservation. Methods We reviewed the history of the development and current methodology used in the analysis of NRS data in the scientific literature and unpublished documents and from our personal knowledge. Results The British Trust for Ornithology's (BTO's) NRS is the largest, longest running and most highly computerized such scheme in the world. Advanced and efficient techniques of data gathering, data capture and analysis are used. It was founded in 1939 to provide information on the breeding biology of birds, but has since developed into a key component of the overall monitoring strategy for birds in the UK. A range of specialized analytical methods is available for NRS data and potential biases need careful treatment. More than 250 scientific publications have used NRS data to describe aspects of basic breeding biol...
98 citations
TL;DR: The results support the hypothesis that food availability independently affects both laying date and clutch size and suggest that a progressive deterioration of natural food sources is the most probable reason for a decline in clutch size as the season advances.
Abstract: CapsuleFood independently affects both laying date and clutch size, suggesting that seasonal decline in clutch size is related to a decrease in food availability. Aim To test the effect of food abundance on laying date and clutch size of the White Stork and identify the cause of seasonal decline in the number of eggs laid. Methods During 1991 and 1996 we recorded clutch size and laying date of pairs breeding next to rubbish dumps (food abundant and constant throughout the breeding season) and birds breeding far from rubbish dumps (using natural food sources). Results In 1991 there was no difference in mean laying date between pairs nesting at rubbish dumps and control pairs. Clutch size was significantly larger at rubbish dump nests. In contrast, mean laying date was earlier in control pairs in 1996 and there was no significant differences in clutch sizes, even when controlling for laying date effect. Conclusion The results support the hypothesis that food availability independently affects both laying da...
70 citations
TL;DR: The lack of positive density-dependent nest predation, the relatively low search effort of foxes near Lapwing nesting sites and the high nest success sometimes achieved in areas with foxes all suggest that Lapwing nest predations by foxes is ‘incidental’.
Abstract: Capsule Lapwing nest predation was negatively correlated to nest density, while Lapwing alarm duration in response to foxes was positively correlated with the number of Lapwing broods present. Aims To identify factors affecting Lapwing nest predation and Red Fox search effort. Methods Lapwing nest success was monitored at four sites in 1996, seven sites in 1997 and six sites in 1998. In 1997 we mapped the position of all Lapwing nests in order to determine distances between nests, and the proximity of linear features and potential avian predator perches to each nest. From April to June 1998 we carried out 199 hours of nocturnal observations at six Lapwing nesting sites using night vision equipment. Results The risk of nest predation was significantly higher for more isolated nests. Nocturnal observations showed that of all the nocturnal predators, foxes were the most active at Lapwing nesting sites. However, fox search effort in Lapwing colonies was relatively low, averaging 57 s/ha per visit. Foxes spent...
61 citations
TL;DR: In this paper, a more elaborated colour-marking approach is recommended for bird migration by delineating the origin of birds and connectivity between breeding and non-breeding grounds, and particular chemical and molecular markers appear to be very useful in the study of bird migration.
Abstract: Capsule Routes and destinations have been unveiled but modern techniques offer the chance to explore much more. Ringing of birds unveiled many mysteries of avian migrations, notably routes and destinations. However, there is still much to be explored by the use of ringing and other marks. Satellite tracking, geolocation and global positioning systems, and even electronic tags may enable much more detailed insights into the migration patterns of individual birds and populations. But also a more elaborated colour-marking approach is recommended. Moreover, particular chemical and molecular markers appear to be very useful in the study of bird migration by delineating the origin of birds and connectivity between breeding and non-breeding grounds. Co-ordinated, collaborative, standardized and large-scale migration networks provide another elaborate tool to study differential migration and patterns of migratory timing and fuelling. Although our understanding of bird migration has gained much from captive studie...
59 citations
TL;DR: In this article, the authors conducted transect surveys on farmland in 100 1-km squares, containing 2885 fields, across Scotland and found that birds, crops, field boundary features and weeds were recorded on three visits.
Abstract: CapsuleExtensive surveys highlighted the importance of weedy fodder brassicas, stubbles and open farmland landscapes to declining birds. Aims To determine habitat associations of seed-eating passerines on Scottish farmland in winter, and recommend appropriate conservation measures. Methods Transect surveys were carried out on farmland in 100 1-km squares, containing 2885 fields, across Scotland. Birds, crops, field boundary features and weeds were recorded on three visits. Bird–habitat associations were examined using logistic regression models. Results Seed-eating passerines were highly concentrated: 100 fields (1.4% of the area surveyed) held half the total count. The highest field densities of birds were recorded in fodder brassica crops and stubbles, averaging 12 and 3.3 birds/ha respectively. In fodder crops, weedier fields held many more birds. Multiple regression analysis emphasized the importance of fodder crops, stubbles and farmyards and suggested that declining bird species preferred more open ...
58 citations
TL;DR: The results show the species' opportunistic feeding and high adaptability, two parameters which need to be known to foresee the consequences on population dynamics, feeding and predatory behaviour of a sudden and severe food shortage, for example due to closure of open-air refuse dumps.
Abstract: Capsule The gulls adjust their diet composition and diversity according to refuse dump accessibility. Aims To examine the influence of the accessibility of open-air refuse dumps on the pre-laying diet of the adult Yellow-legged Gull. Methods We studied six colonies settled on six rocky islands off the southeastern coast of France. A comparative study of the diet of breeding adults from the six colonies was made through pellet analysis (a total of 848 pellets). We determined the main foraging habitat used (refuse dumps, terrestrial habitats, marine habitat) and the number of foraging habitats used simultaneously (one, two or three), from which we deduced the mean diet diversity. Results Refuse dumps were consistently the main foraging habitat (evidence in 53–74% of pellets) for the six colonies, even when refuse dump accessibility was low. The majority of pellets contained materials from two simultaneous foraging habitats (evidence in 50–64% of pellets). We demonstrated the influence of a gradient of refus...
52 citations
TL;DR: Vegetated field boundaries are an important foraging habitat for Swallows and support higher prey densities than field centres, especially when adjacent fields are arable.
Abstract: Capsule The loss of hedgerows may have reduced the quality of agricultural land for breeding Swallows. Aims To test if foraging Swallows select vegetated field boundaries in preference to field centres, if selection is influenced by weather conditions and local habitat type, and if patterns of selection are explained by differences in food availability between the two habitats. Methods Data were collected from paired vegetated field boundaries and field centres in lowland mixed farmland during good and bad weather conditions. The maximum number of foraging Swallows, total foraging time, food availability and local habitat type (adjacent crop type, presence/absence of boundary trees and boundary height) were recorded. Results Foraging Swallows selected vegetated boundaries in bad weather and there was a non-significant trend towards selection during good weather. Hedgerow use increased significantly when the adjacent field was winter wheat, rather than grazed grass. Hedgerows containing trees were used mor...
43 citations
TL;DR: Within-pair comparisons substantially improve the accuracy of sexing from biometrics for two congeneric species of seabird with monomorphic plumage and soft-tissue colouration and can eliminate the need to calculate cut points or discriminant functions from a sample of birds of known sex for each particular study.
Abstract: Capsule Within-pair comparisons substantially improve the accuracy of sexing from biometrics for two congeneric species of seabird with monomorphic plumage and soft-tissue colouration. Aims To examine the extent to which statistical limitations of sexing birds from biometrics using sample-level analysis could be overcome by sexing Common and Arctic Terns (Sterna hirundo and S. paradisaea) using measurements obtained from breeding pairs. Methods Incubating adults were caught at the nest using walk-in traps and wing, tarsus, head-plus-bill, tail length, tail fork, and body mass measured. Each bird was individually colour-ringed and dyed with picric acid, enabling subsequent sexing by behavioural observations of copulation and courtship feeding. Birds were sexed using biometrics and the proportion of birds sexed correctly this way at the sample level was compared with the accuracy achieved if, within a pair, the larger bird was classified as male. Results Head-plus-bill length was the single most accurate me...
42 citations
TL;DR: In this article, the evidence for declining swallow populations in Britain, based on the British Trust for Ornithology's long-running Common Birds Census (CBC) and suggest possible causes.
Abstract: Capsule There are regional and habitat differences, but no long-term decline in numbers. Aims To review the evidence for declining Swallow populations in Britain, based on the British Trust for Ornithology's long-running Common Birds Census (CBC) and suggest possible causes. Methods Trends were fitted to CBC data for 1964–98 using a generalized linear modelling framework and analysed with regard to specific regions and habitats. Current habitat use, particularly of different farming types, was characterized using data from the Breeding Bird Survey. Correlations between Swallow population size and loss of nest-sites and rainfall in the non-breeding grounds were examined. Results Although Swallow numbers show large annual fluctuations, there is no evidence for a long-term decline on CBC plots. Numbers seem to have declined on farms in eastern England and in non-farmland habitats, but were not correlated with changes in cattle numbers or with an index of regional changes in nest-site availability. The number...
38 citations
TL;DR: Most species or guilds did not show significant responses to the pilot Arable Stewardship Scheme, although there were statistically significant positive effects on some key target groups, including breeding Lapwing Vanellus vanellus and wintering granivorous passerines.
Abstract: CapsuleFew positive responses by birds were observed in the first two years of this new agri-environment scheme. Aims To determine whether the pilot Arable Stewardship Scheme delivered increased populations of either breeding or wintering birds. Methods Birds were surveyed on both scheme and control sites. In the breeding season, a modified Breeding Bird Survey methodology was employed. Complete counts of all birds on each site were conducted in winter. Differences in numbers, or in the change in numbers between the first and second years, between scheme and control sites were assessed by multiple log-linear regression. Results Most species or guilds did not show significant responses to the scheme, although there were statistically significant positive effects on some key target groups, including breeding Lapwing Vanellus vanellus and wintering granivorous passerines. Conclusion The potential reasons for the lack of significant results, including the short length of the monitoring programme, are discusse...
36 citations
TL;DR: Variation in food availability did not seem sufficient to override the overall importance of indices of parental quality in determining reproductive measures and chick provisioning, and there was some indication that egg size may explain variation in fledging weight and the amount of food received by chicks.
Abstract: Capsule Timing of breeding influenced wing-length at fledging, and egg size may be an indicator of fledging weight and the amount of food received by chicks. Aims To investigate chick growth, temporal patterns of chick food provisioning and the importance of indices of parental condition or quality, egg size and hatching date, to predict nestling body mass and wing-length at fledging, and compare breeding and chick feeding characteristics between colonies in the northeast Atlantic. Methods A survey of Cory's Shearwater nests was carried out at Vila islet. A sample of 52 chicks, ringed and weighed at hatching, was selected to study chick growth and food provisioning. Results Hatching success (51%) was much lower than fledging success (87%). Both hatching date and egg size contributed to explain wing-length at fledging, but hatching date, which was negatively correlated with wing-length at fledging, had the most important contribution (22%). There was some indication that egg size may explain variation in f...
TL;DR: Predation rates of Golden Plover nests and chicks can be low on moorlands managed for shooting Red Grouse, however, in the absence of predation, other factors may still reduce chick survival and limit breeding success.
Abstract: Capsule The best estimate of breeding success was a mean of 057 fledglings per pair, which when combined with adult survival rates, successfully explained the observed population trend Aims To quantify Golden Plover breeding success on a moor managed for shooting Red Grouse Lagopus lagopus Methods An intensive study recorded the fate of individual Golden Plover nests and, using radiotelemetry, chicks The factors associated with mortality were examined, allowing the construction of a model of breeding success Adult survival was estimated from return rates of colour-ringed birds Results Estimated rates of daily nest survival during laying (08636) were significantly lower than during incubation (09913) The daily survival rate of chicks less than nine days (08868) was significantly lower than for older chicks (09792) A population model based on these parameters overestimated the rate of nest losses, but accurately described brood survival and fledging success Although predation rates were low, po
TL;DR: Birds from Switzerland and England probably winter in geographically distinct parts of Africa, and the Swiss birds probably feed on prey that are more reliant on C3 vegetation, from woodlands, than the prey of English birds, which are more reliance on C4 vegetation from grasslands.
Abstract: Capsule Stable isotope analysis of Swallow feathers, grown in Africa, revealed significant differences between populations breeding in Switzerland and England. Aims To investigate the extent to which Swallow populations breeding in Switzerland and England are separated on their African wintering grounds. Methods Swallows were caught at breeding colonies, biometric measurements were taken and feathers, grown in Africa, were collected. Feathers were combusted in a Carlo Erba C/N/S analyser and the δ13C and δ15N signatures were measured using a mass spectrometer. Results The δ13C signatures of Swiss birds were significantly more depleted than those of birds from England. The δ15N signatures did not differ between the two populations. Conclusion Birds from Switzerland and England probably winter in geographically distinct parts of Africa. The Swiss birds probably feed on prey that are more reliant on C3 vegetation, from woodlands, than the prey of English birds, which are more reliant on C4 vegetation, from g...
TL;DR: The authors' estimate using mapping is less than previously reported using transects, and the total area affected by climate change is believed to be about one-third of what was previously reported.
Abstract: Capsule Our estimate using mapping is less than previously reported using transects.
TL;DR: The results suggest that seed production may be limited within government agri-environment schemes by restrictions on fertilizer use, and the agronomy of seed-bearing crops for birds requires further investigation.
Abstract: Capsule Declining farmland species were more abundant in these crops which can be matched to the birds' requirements. Aims To assess the use of seed-bearing crop by a range of bird species in winter. Methods The study was carried out over three winters at a site in County Durham (England). Eleven bird species were represented, five of which are nationally targeted for conservation action. Results Bird abundance was significantly higher where wild bird cover crops were present. Kale Brassica napus and Quinoa Chenopodium quinoa were the most used crop species, although cereals and linseed were also used. Conclusion Simple crop mixtures can be designed to meet the needs of farmland bird communities. Our results suggest that seed production may be limited within government agri-environment schemes by restrictions on fertilizer use. The agronomy of seed-bearing crops for birds requires further investigation.
TL;DR: The results suggest that by changing food distribution, edge effects on pine cone production may be significantly involved in local changes in the social structure of the Coal Tit.
Abstract: Capsule Individuals concentrated near forest edges in bigger social groups than in forest interiors and foraged more on pine cones which were more abundant there. Aims To evaluate differences in food distribution between forest edges and forest interiors and their effects on the non-breeding flocking patterns of Coal Tit populations inhabiting mountain coniferous forests. Methods We collected cone production data at forests edges and interiors in mountain pine forests located in the Pyrenees (northeast Iberian peninsula). At the same sites, we also quantified Coal Tit abundance, flocking patterns and foraging behaviour by means of paired bird surveys during autumn and early winter. Results We recorded a larger abundance of pine cones available on trees along forest edges compared with forest interiors. Coal Tit groups were of bigger size along forest edges, although the number of social groups detected did not differ from forest interiors. Our observations on foraging behaviour supported the hypothesis that differences in flock sizes and overall abundances associated with distance to the edge are due to differences in the availability of pine cones and to the heavier use of these foraging substrates by birds along forest edges. Conclusions Our results suggest that by changing food distribution, edge effects on pine cone production may be significantly involved in local changes in the social structure of the Coal Tit. An increase in resource heterogeneity and local population density may have important implications at a population level, such as favouring mobility of individuals searching for food resources and thus a transient life, and increasing the costs of territory defence to resident individuals.
TL;DR: In this article, the authors investigated life history parameters that may be responsible for a population growth since the 1990s in La Crau and found that local first-year survival is higher than in Spain with a high proportion of first year birds returning to their natal area.
Abstract: Capsule Local first-year survival is higher in La Crau than in Spain with a high proportion of first-year birds returning to their natal area. Aims To understand life history parameters that may be responsible for a population growth since the 1990s. Methods Between 1994 and 1998, 342 birds were ringed as fledglings. From capture–recapture data, annual local survival and the proportion of first-year birds returning to their natal area were computed. Results The annual survival probabilities of adult and first-year birds were constant during the study period (0.67 and 0.57, respectively). A high proportion (0.72) of birds ringed as fledglings returned to their natal area after one year. Of these, an estimated 53% bred in that first year. Local first-year survival is higher in La Crau than other areas in Spain. Conclusion The high local survival rate, the product of survival and philopatry, might be responsible for the positive trend of the population. A peculiar aspect of the La Crau population is that gro...
TL;DR: The abundance of Ring Ouzels was linked to heather–grass mosaics, while declines were greater in tetrads lacking topographical features known to be selected by nesting ouzels, suggesting that large-scale afforestation of the uplands is a cause of concern.
Abstract: CapsuleThe change was correlated with environmental, habitat and management variables. Aims To identify factors correlated with a population decline and range contraction between 1988–91 and 1999. Methods Regression models are used to describe the variation in Ring Ouzel abundance in 1988–91, and the change in Ring Ouzel abundance between 1988–91 and 1999. Results The abundance of Ring Ouzels in 1988–91 was negatively correlated with improved pasture, but positively with heather/smooth grass mosaic and Nardus/Molinia grassland. There was also a positive quadratic correlation with rock cover. A decline in Ring Ouzels between 1988–91 and 1999 was most likely on tetrads with shallow gradients, and outside of a 350–750 m altitudinal range. The change in ouzel numbers was also negatively correlated with both the initial area of conifer forest and heather/smooth grass mosaic. The rate of loss was greatest in those areas with a low Ring Ouzel abundance in 1988–91, although this effect was non-significant once ha...
TL;DR: A review of the progress of field ornithology in Britain in the context of Bird Study and the British Trust for Ornithology is presented in this paper, where an overview of the main subject areas published in Bird Study to characterize progress over 50 years is presented.
Abstract: Capsule Field ornithology is alive and well, and in the future can contribute much more in Britain and elsewhere. Aims To review the progress of field ornithology in Britain in the context of Bird Study and the British Trust for Ornithology. Methods An overview was taken of the main subject areas published in Bird Study to characterize progress over 50 years. Some quantification of data on the main bird organizations was performed. ResultsKnowledge of status and trends of British birds has moved from the qualitative to generally well detailed quantitative over the past 50 years. Causes of distribution and changes are increasingly well understood in terms of habitat and of population processes. Behaviour and ecology have grown to be separate disciplines in their own right although birds have been major subjects of study within them. Migration studies have lagged somewhat in Britain but advanced elsewhere in recent decades. Amongst the main bird organizations, the BTO still has a growing membership, that of...
TL;DR: Anti-predator behaviour was species-specific, depending on type of predator, habitat and nest inaccessibility, as parents did not approach the nest in the presence of a predator.
Abstract: Capsule Three similarly sized passerine species with various breeding strategies behaved differently in the presence of models of mammalian and avian predators. Aims We tested whether solitary breeders behave in the presence of a predator in order to avoid disclosing their nest site in: hole-nesting Pied Flycatcher Ficedula hypoleuca, shrub-nesting Blackcap Sylvia atricapilla and ground-nesting Meadow Pipit Anthus pratensis. Methods The behaviour of parents in response to two types of predator model (visually oriented Corvid birds and olfactory oriented Mustelid mammals) placed sequentially at 40, 5 and 1 m distance from the nest was recorded from a shelter. Results The hypothesis was supported in open-nesting species (Meadow Pipit and Blackcap), as parents did not approach the nest in the presence of a predator. In the hole-nesting Pied Flycatcher the parents disclosed the nest site in most cases (by entering the nest). The intensity of alarm calling increased with decreasing distance of a predator from ...
TL;DR: Iberian breeders appear better suited to long-distance migration than wintering individuals, which strongly supports the hypothesis that brehmii move south of the Sahara in autumn and are substituted by central European collybita populations in winter.
Abstract: Capsule Iberian Chiffchaffs Phylloscopus (collybita) brehmii are genetically, morphologically and bioacoustically different from European Chiffchaffs (P. [c.] collybita). Aim To examine the difference in migratory pattern between brehmii and collybita. Methods We inferred variation in distance of migration between brehmii and collybita by analysing differences in flight-related morphology (wing-length, wing shape and tail-length) between individuals breeding or wintering in the Iberian Peninsula. Results Controlling for body size and allometry of feather dimensions, birds captured in spring had more pointed wings (more concave wing shapes and pointed wing tips) and a shorter tail than birds caught in winter, although no spring-to-winter difference was found for wing-length. Conclusion Iberian breeders appear better suited to long-distance migration (their traits are likely to give a higher speed and a lower energy consumption during long non-stop flights) than wintering individuals, which strongly supports the hypothesis that brehmii move south of the Sahara in autumn and are substituted by central European collybita populations in winter. This different migration pattern of brehmii and collybita has important implications for the maintenance of differentiation in their contact zone, because selection against hybrids with maladaptive, intermediate migratory behaviours might contribute to reproductive isolation.
TL;DR: Eight species have increased and five have declined in the UK since the 1984–85 survey and the possible reasons for the declines of Ringed Plover, Sanderling, Purple Sandpiper, Bar-tailed Godwit, Turnstone and Turnstone are discussed.
Abstract: Capsule An updated estimate is presented and major declines in the internationally important populations of several species identified. Aims To provide population estimates of the waders overwintering on the UK and Isle of Man's non-estuarine coasts. Methods UK-NEWS was a repeat of the 1984–85 Winter Shorebird Count (WSC). The WSC results were reanalysed to allow direct comparison with the UK-NEWS results. The new population estimates are provided with bootstrapped confidence intervals. Results UK-NEWS covered 4959 km or 38% of the UK's non-estuarine coastline and recorded over 170 000 waders of 19 species. The new population estimates for the UK's non-estuarine wader species are as follows (values in parentheses are percentages of the East Atlantic Flyway population of each species): 70 790 Oystercatcher Haematopus ostralegus (7%), 24 110 Ringed Plover Charadrius hiaticula (33%), 28 670 Golden Plover Pluvialis apricaria (2%), 2175 Grey Plover Pluvialis squatarola (1%), 41 180 Lapwing Vanellus vanellus (1...
TL;DR: The Blackbird population of the study area forages extensively on the energy-rich Laurel fruits, while the plants depend exclusively on this bird species for seed dispersal, and consequences of the depauperate frugivore community and the tight mutualism between Blackbirds and Laurels on plant recruitment and conservation are discussed.
Abstract: Aims To describe a present-day frugivore assemblage of natural Laurel populations in southern Spain. Methods Eight fruiting trees of different size were monitored with binoculars during 52 hours spread across one ripening season, and the identity and behaviour of foraging birds were recorded. Additional point counts were used to record the avifauna of the surroundings. Results Despite a diverse frugivore community being present, Laurel fruits are almost exclusively (99%) consumed by Blackbird and rarely (1%) by Blackcap Sylvia atricapilla. Blackbirds concentrate at fruiting trees and individuals may remain there for several days. Birds usually forage in small groups and return at intervals of 12‐14 minutes. Conclusion The Blackbird population of the study area forages extensively on the energy-rich Laurel fruits, while the plants depend exclusively on this bird species for seed dispersal. Consequences of the depauperate frugivore community and the tight mutualism between Blackbirds and Laurels on plant recruitment and conservation are discussed.
TL;DR: With the exception of ducklings, Marbled Teal differs in its ecology from the better-known north-temperate ducks, they are less dependent on invertebrates and rely on small seeds more than north- Temperate ducks.
Abstract: CapsuleThis globally threatened species is less dependent on invertebrates and more dependent on seeds than other ducks. Aims To assess seasonal variation in Marbled Teal diet at two of the most important wetlands for the west Mediterranean population. Methods Faecal samples from El Hotba, Morocco (19 in October, 28 in May) and Veta la Palma, Donana (19 in August, five from July broods) were analysed. Gut contents of six birds from Veta la Palma (September–October) were analysed. Results At El Hotba, small seeds (especially Ruppia) and green plant material (especially charophytes) were the dominant faecal components in May and October. The proportion of invertebrates did not change, but more Corixidae and less Chironomidae were consumed in May. At Veta la Palma, Ruppia seeds were dominant in August, but Ephydridae, Chironomidae, Coleoptera and other insects were dominant in faeces from July broods. Significantly fewer Coleoptera but more Foraminifera were recorded in August. The overall proportion of inve...
TL;DR: In this paper, the authors examined individual and seasonal variation in site fidelity, habitat use, range size and foraging strategies of Barnacle Geese Branta leucopsis, and found that birds from one of the two capture sites tended to be more sedentary and have smaller home ranges.
Abstract: CapsuleBarnacle Geese restrict their movements to relatively few key sites and exhibit considerable variation in ranging behaviour. Aims To examine individual and seasonal variation in site fidelity, habitat use, range size and foraging strategies of Barnacle Geese Branta leucopsis. Methods The movements of 18 male Barnacle Geese tagged in two discrete areas were tracked for 3–6 months from late autumn until departure on the spring migration. Results Tagged geese concentrated their feeding in a relatively small proportion of apparently suitable habitat. Geese moved increasingly further afield in midwinter, and there was a clear predeparture shift to the largest area of relatively undisturbed, and possibly more nitrogen-rich, saltmarsh on the Solway. Birds from one of the two capture sites tended to be more sedentary and have smaller home ranges. Conclusion There is considerable between-site and inter-individual variation in the degree of site-faithfulness of Barnacle Geese.
TL;DR: Aquatic invertebrates in shallow pools can be an important component of the diet of breeding Lapwing and Redshank in May and June, but most management of coastal grazing marsh set out in ESA agri-environment schemes only specifies retaining pools until the end of April.
Abstract: Capsule Management of coastal grazing marshes for these breeding wading birds should prescribe maintaining shallow pools in May and June instead of until the end of April as currently set out in most coastal grazing marsh ESA agri-environment schemes. Aims To determine the range of prey and most important components of the diet of breeding Lapwing and Redshank on coastal grazing marsh throughout the breeding season. Methods Prey were determined from remains in faeces and pellets. The contributions of these prey to the diet were estimated by multiplying selected prey remains by published correction factors and dry weights of intact prey. Results Adult Lapwing and chicks and adult Redshank fed on a wide range of soil, surface-active and aquatic invertebrates. Adult Redshank also fed on estuarine invertebrates. The proportion of aquatic invertebrates in the diet of both species increased as the breeding season progressed, while that of soil invertebrates decreased. Conclusion Aquatic invertebrates in shallow...
TL;DR: Investigating foraging Hen Harrier activity in relation to vegetation cover and structure and the abundance of potential prey found conifer forests can provide favourable conditions for foraging harriers during the early growth stages.
Abstract: Capsule In west Scotland, the birds foraged in accordance with the distribution of prey and vegetation associated with early-growth conifer forests. Aims To investigate foraging Hen Harrier activity in relation to vegetation cover and structure and the abundance of potential prey. Methods Forty 1 × 1-km sample observation areas were monitored at four sites in west Scotland. Results Foraging time in the sample squares was dependent on the proximity of harrier nests. Harriers preferred areas with relatively high densities of Field Voles Microtus agrestis and Meadow Pipits Anthus pratensis, associated with tall ground vegetation and shrub layers. They also preferred areas planted with trees but preference declined with increasing tree foliage 2–5 m tall and bare ground. Conclusion Conifer forests can provide favourable conditions for foraging harriers during the early growth stages. Further work is required to determine the value of other types of woodland.
TL;DR: In this paper, a set of models were used to model the annual and seasonal survival of several shorebird species at Teesmouth, northeast England, using 25 years of colour-ring resightings.
Abstract: Capsule Serious violations of the model assumptions were seen. Aims To illustrate the manner in which violations of the mark–recapture model assumptions may occur. Methods Attempts were made to model annual and seasonal survival of several shorebird species at Teesmouth, northeast England. The database contained 25 years of colour-ring resightings and several suites of models were tested. Results There was significant heterogeneity in survival and recapture probabilities for all five species of shorebird that had been colour-marked. Various attempts and blocking, stratifying and constraining our survival models, while in many cases providing more parsimonious solutions, had no effect on these heterogeneities. Conclusions Our problems stem from both the methodology used and lack of information about the status of individuals (e.g. territoriality and variability in the level of site fidelity). We suggest ways in which data more appropriate to survival analyses might be collected in future.
TL;DR: The variation in population trends between surveys during 1964–81 and in 1999 and 2000 can be explained by nest-site loss, and possibly agricultural intensification.
Abstract: Capsule The variation in population trends (−86% to +236%) between surveys during 1964–81 and in 1999 and 2000 can be explained by nest-site loss, and possibly agricultural intensification.
TL;DR: In this article, the responses of Robins to playbacks of conspecific song were measured during daylight and at night on territories illuminated by streetlights, and compared Robins in Wales and Ireland.
Abstract: Capsule Birds subjected to playbacks of conspecific song responded strongly by day in both Wales and Ireland, and strongly at night only in Wales. Aims To test the responses of Robins to conspecific playbacks between Wales and Ireland and between day and night. Methods We measured the responses of Robins to conspecific playbacks during daylight, and at night on territories illuminated by streetlights, and compared Robins in Wales and in Ireland. Results Most Welsh Robins responded to playbacks at night, whereas Irish Robins rarely responded. Both populations responded equally during daylight. Conclusion We show for the first time that different populations with similar daytime behaviours may differ in nocturnal behaviour. Such population differences in communication behaviour should be taken into account, for example when using acoustic playback to census populations.