Bird Study最新文献

{"title":"Analysis of the trans-Saharan migration and wintering areas of GPS-tagged Cinereous Vultures Aegypius monachus","authors":"Jorge García-Macía, Marc Gálvez, Gerard Plana, Núria Vallverdú, Ernesto Álvarez, Manuel Galán, Juan José Iglesias-Lebrija, Vicente Urios","doi":"10.1080/00063657.2023.2274312","DOIUrl":"https://doi.org/10.1080/00063657.2023.2274312","url":null,"abstract":"Although the western Mediterranean population of the Cinereous Vulture Aegypius monachus is considered to be mainly resident, a small but increasing number of individuals migrate between western Eu...","PeriodicalId":55353,"journal":{"name":"Bird Study","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2023-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138514418","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Habitat and other environmental correlates of the decline of breeding Whinchats <i>Saxicola rubetra</i> in the UK since the mid-1990s","authors":"Andrew J. Stanbury, Robert W. Hawkes, Emma L. Teuten, Irena Tománková, David J.T. Douglas","doi":"10.1080/00063657.2023.2264560","DOIUrl":"https://doi.org/10.1080/00063657.2023.2264560","url":null,"abstract":"ABSTRACTCapsule Declines in Whinchat Saxicola rubetra breeding abundance in the UK vary with habitat and other environmental conditions.Aims To test for associations between changes in Whinchat abundance between 1994 and 2018 and measures of habitat and environmental conditions on UK breeding sites.Methods Whinchat counts collected through a national monitoring scheme were tested at coarse 1 km2 square and finer 200 m transect scales against habitat data collected in 2017/2018, plus remotely sensed data to test for long-term change.Results At the 1 km2 square scale, mean change in Whinchat abundance was more negative where woodland occurred more frequently, and at more northerly latitudes. Rates of decline were lower where there was greater cover of Purple Moor-grass Molinia caerulea and non-bracken vegetation height was taller. At the finer 200 m transect scale, more closely resembling Whinchat territory size, rates of decline were greatest in areas dominated by human sites, woodland, and enclosed farmland, compared to unenclosed open semi-natural habitats; however, within the latter category, declines were lower in grass-dominated relative to heather-dominated habitats. Rates of decline were also lower closer to valley bottoms, with greater Bracken Pteridium aquilinum cover and at mid-elevations (300 m), and greatest where there was greater cover of bare ground and trees, and moderate cover of grasses (excluding Molinia and Lolium spp.). The strength of the finer-scale associations varied between dominant habitat types. Whinchat abundance was lower where a remotely sensed index of vegetation productivity (normalized difference vegetation index [NDVI]) was higher, and abundance change more negative where temporal increases in NDVI were greater.Conclusion Unenclosed semi-natural grassland showed the lowest rate of decline and offers the best opportunities to conserve Whinchats. Woodland expansion is likely to have a detrimental impact on breeding Whinchats. Future research should investigate how important habitat and environmental correlates influence key demographic rates affecting recruitment. AcknowledgementsWe thank the many volunteers who have taken part in the BTO/JNCC/RSPB Breeding Bird Survey, without whom, such comparison studies would not be possible. We thank Dartmoor National Park Authority, Exmoor National Park Authority, and the Exmoor Society/MacEwen Trust for their financial contributions, and are grateful to Andrew Bradbury, James Gordon, and Gareth Thomas for collecting much of the field data for the project, and to Dawn Balmer, Helen Booker, Graeme Buchanan, Malcolm Burgess, and Sarah Harris for their assistance, and Álvaro Ramírez and the anonymous reviewers for providing comments on previous versions of the paper.Disclosure statementNo potential conflict of interest was reported by the author(s).","PeriodicalId":55353,"journal":{"name":"Bird Study","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136348200","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The status of breeding Red-throated Divers <i>Gavia stellata</i> and Black-throated Divers <i>Gavia arctica</i> in Kintyre, Scotland, 2016–2020","authors":"Rafe Dewar, Simon Lawrence","doi":"10.1080/00063657.2023.2272599","DOIUrl":"https://doi.org/10.1080/00063657.2023.2272599","url":null,"abstract":"ABSTRACTCapsule An onshore wind farm monitoring programme carried out across Kintyre, Scotland from 2016 to 2020 provided an insight into the status of the area’s breeding Red-throated Diver Gavia stellata and Black-throated Diver Gavia arctica populations and their current threats.Aims This study provides an example of targeted monitoring undertaken for a renewables development which can inform conservation decision-making at a population and species level. The aims were to: (i) determine the population status of the breeding diver populations; (ii) determine whether the Cour Wind Farm, or other wind farms in Kintyre, have had any effects on the populations; and (iii) identify the most likely conservation threats to breeding divers within Kintyre.Methods Annual breeding diver surveys across Kintyre recorded presence, breeding activity and productivity. Within the Cour Wind Farm site carcass searches were conducted to record any incidences of diver collisions with wind turbines.Results Divers were recorded on approximately one third of waterbodies monitored in each year. The current Kintyre breeding populations are estimated to be 18–23 Red-throated Diver pairs, and between two and six Black-throated Diver pairs. The Kintyre Red-throated Diver population appears to have lower productivity rates than the UK average. Predation and interspecific competition may be limiting breeding success. No Black-throated Divers were observed to have successfully bred in Kintyre from 2016 to 2020, which may be partly due to a shortage of waterbodies with preferred conditions for nesting. No diver collisions were recorded during carcass searches and there is no evidence to suggest that the Cour Wind Farm is influencing the numbers or distribution of divers.Conclusion The Kintyre Red-throated Diver population may be, and the Black-throated Diver population is likely to be, in unfavourable condition. Opportunities for conservation should be considered, particularly to manage waterbodies so that they are optimal for breeding. AcknowledgementsThe monitoring programme was originally initiated and designed by the late Paul Haworth of Haworth Conservation. Surveys were coordinated by Haworth Conservation in 2016 and by MacArthur Green from 2017 to 2021. The surveyors were Dr Simon Lawrence, Aidan Maccormick, Will Self and Charlie Self. Thanks go to Octopus Investments for allowing these results to be published and to Blair Urquhart at Natural Research Ltd for help in coordinating data sharing. Scott Smith also assisted with baseline wind farm data sharing on divers as did Gavia Environmental Ltd and Chris Cathrine at Caledonian Conservation Ltd.Disclosure statementThe employer of Rafe Dewar (MacArthur Green) was contracted to undertake the bird monitoring programme by BayWa r.e., who provided technical and commercial asset management of Cour Wind Farm for Octopus Investments. MacArthur Green contracted Simon Lawrence to carry out some of the bird monitoring. The authors ","PeriodicalId":55353,"journal":{"name":"Bird Study","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136283303","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Wintering and migration strategies of Slavonian Grebes <i>Podiceps auritus</i> breeding in Iceland","authors":"Thorkell Lindberg Thórarinsson, Benjamin Merkel, Adalsteinn Orn Snaethórsson, Yann Kolbeinsson","doi":"10.1080/00063657.2023.2269330","DOIUrl":"https://doi.org/10.1080/00063657.2023.2269330","url":null,"abstract":"ABSTRACTCapsule Slavonian Grebes Podiceps auritus breeding in Iceland moult on freshwater, before migrating to the seas around the British Isles for the winter.Aims The aims were to describe the migration strategies and identify wintering areas of Slavonian Grebes breeding in Iceland.Methods Geolocators were fitted to 37 Slavonian Grebes breeding on two lakes in north-east Iceland from 2009 to 2012. Of these, 19 were recovered and provided useful data on wintering areas and migration timing.Results The results indicated that the grebes moulted on freshwater lakes before gradually moving to the sea and later migrating to the wintering areas. Most of the birds wintered on the sea around the British Isles. However, there was surprisingly high variation in wintering strategies and little overlap of wintering areas. Grebes tracked for consecutive years showed high wintering philopatry.Conclusion Individual Slavonian Grebes may be vulnerable to local environmental conditions, but the high variability in wintering strategies and relatively large non-breeding distribution is expected to make the population generally less sensitive to local environmental conditions in the wintering areas over the long term. AcknowledgementsWe thank Ellen Magnúsdóttir for technical assistance and Ib Krag Petersen for advice regarding the geolocators and attachment methods. We are also grateful to landowners at lake Víkingavatn and the Vatnajokull National Park authorities for access to the nesting area of the Slavonian Grebes. Finally, we warmly thank Sesselja Gudrun Sigurdardóttir and Sunna Bjork Ragnarsdóttir for their fieldwork participation. All work carried out for this study complies with the current law and regulations in Iceland. Ringing permit was provided by the Icelandic Institute of Natural History.Disclosure statementNo potential conflict of interest was reported by the author(s).","PeriodicalId":55353,"journal":{"name":"Bird Study","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136283298","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Human-facilitated feeding on Date Palm <i>Phoenix dactylifera</i> sap by trans-Saharan warblers during spring stopover in a Tunisian oasis","authors":"Fatma Belani, José Javier Cuervo, Slaheddine Selmi","doi":"10.1080/00063657.2023.2270228","DOIUrl":"https://doi.org/10.1080/00063657.2023.2270228","url":null,"abstract":"ABSTRACTCapsule Some trans-Saharan warbler species feed on human-extracted Date Palm Phoenix dactylifera sap during spring migratory stopover.Aims To investigate the behaviour of birds feeding on Date Palm sap at a Tunisian oasis during the spring migration season.Methods Birds feeding on Date Palm sap were monitored during the peak of spring migratory passage of trans-Saharan birds in southern Tunisia by recording the species involved and their numbers, and noting whether there were agonistic interactions between them. Data were used to describe the assemblages of birds feeding on Date Palm sap.Results We recorded five trans-Saharan warbler species feeding on Date Palm sap, either in single- or mixed-species flocks. Aggressive conflicts were common, suggesting competition by interference within this bird assemblage. However, other abundant fruit-eating trans-Saharan warbler species were never seen feeding on Date Palm sap, possibly due to the potential inability to assimilate some of its components, or simply because they did not need to ingest it for reasons related to their migration strategy.Conclusions Our findings reveal that Date Palm sap is a food resource for some trans-Saharan warbler species, highlighting a rarely documented human-facilitated feeding behaviour in birds. They also underline the high ecological plasticity of these warbler species, capable of using different food resources to meet the needs of their challenging migratory journey. AcknowledgementsThe authors thank the farmers and palm tappers in Kettana Oasis for their kind support during the fieldwork. The authors also thank all members of the Ecology of Terrestrial Fauna research unit for valuable discussions on this work. Comments provided by the Editor and an anonymous reviewer greatly improved the manuscript and were much appreciated. This study complies with the current laws of Tunisia. Permits were obtained from the Forest Service of the Tunisian Ministry of Agriculture (permit reference: 437-07/02/2022).Disclosure statementNo potential conflict of interest was reported by the authors.Additional informationFundingThis study was funded by the Spanish National Research Council (CSIC), project COOPA20475, and was part of the activities of the ‘Ecology of Terrestrial Fauna’ research unit, supported by the Tunisian Ministry of Higher Education and Scientific Research.","PeriodicalId":55353,"journal":{"name":"Bird Study","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135390936","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Traditional landscape elements are key to the threatened Ortolan Bunting <i>Emberiza hortulana</i> in its Italian stronghold","authors":"Vincenzo Alfano, Marco Gustin, Mattia Brambilla","doi":"10.1080/00063657.2023.2273805","DOIUrl":"https://doi.org/10.1080/00063657.2023.2273805","url":null,"abstract":"ABSTRACTCapsule Cultural landscapes with Tamarisk Tamarix gallica rows, marginal habitats and crop heterogeneity promote the occurrence of Ortolan Buntings Emberiza hortulana in the Marche region, a key area for the species’ conservation in Italy.Aims To evaluate the land-use determinants of the occurrence of the Ortolan Bunting, a species strikingly declining in recent decades.Methods Within the Marche region, the Italian stronghold of the species, we surveyed 20 plots in the hilly belt of Pesaro-Urbino province, and recorded different potential land-cover drivers of the occurrence of Ortolan Buntings. We modelled habitat selection according to environmental variables measured in the field at an equal number of territory and control sites, using generalized linear models.Results We found 104 territories of Ortolan Buntings. Different groups of predictors (crop cover, marginal habitats, other land-uses) were similarly important; positive drivers of the species’ occurrence were the covers of cereal, dead trees, pure and mixed Tamarisk rows, other crops, sunflower, and reeds; covers of broom had a quadratic effect, while negative effects were found with seminatural grassland, paved roads, and isolated shrubs. The disappearance of cultural landscapes, which is ongoing in many European areas, resulted in the loss of elements typically found in low-intensity farming systems and of particular importance for the species. Tamarisk rows may provide multiple benefits, offering song posts and potential nesting sites close to the ground, and their abundance in the Marche region could contribute to explain why Ortolan Buntings are locally more common there, compared to other Italian regions.Conclusions The maintenance of Tamarisk rows, marginal habitats and crop heterogeneity are key measures needed to support Ortolan Bunting populations. Disclosure statementNo potential conflict of interest was reported by the author(s).","PeriodicalId":55353,"journal":{"name":"Bird Study","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135341874","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A preliminary study of the winter roosting behaviour of four woodland passerines","authors":"M. J. O’Connell, F. I. Squirrell, M. Greening","doi":"10.1080/00063657.2023.2269329","DOIUrl":"https://doi.org/10.1080/00063657.2023.2269329","url":null,"abstract":"ABSTRACT Capsule Radio-tracking of four woodland passerine species reveals variation in winter roost site selection within and between species. Aims To evaluate methods for studying winter roosting behaviour in woodland passerines and to collect preliminary data on intra- and inter-specific differences in roost site characteristics and spatial arrangement. Methods Ten woodland birds (three Eurasian Blackbirds Turdus merula, three Dunnocks Prunella modularis, two Great Tits Parus major and two European Robins Erithacus rubecula), were fitted with a tail-mounted Lotek PicoPip AG337 VHF radio tag (January to March 2022). Tagged birds were located by triangulation, and nightly winter roost locations identified and characterized. A geographic information system was used to quantify roost site fidelity, roosting height and types of habitats used. Results Manual tracking of birds with radio tags is a cost effective and appropriate method for studying passerine winter roosting behaviour. Sample sizes were too small to allow exploration of significant differences between sites, age and sex. European Robins showed the greatest site fidelity in relation to between-night roost positions, with Eurasian Blackbird, Great Tit and Dunnock being more variable in the sites chosen between nights. Eurasian Blackbird and Great Tit roost sites were generally higher above the ground (up to 6 m), compared to European Robins and Dunnocks (all sites less than 4 m above the ground). Eurasian Blackbirds varied the most in the number of habitats used for roost sites, and European Robins showed the least variation. Only three out of 11 habitat types (bramble Rubus sp, laurel Prunus sp. and Sycamore Acer pseudoplatanus with Ivy Hedera helix) were used by more than one species as a roosting habitat. Conclusion Further research should focus on: (1) habitat use in relation to relative availability; (2) increasing samples sizes to allow comparison of factors such as age, sex and sites; (3) the impact of supplementary feeding on roosting behaviour; (4) quantifying the thermal properties of roost sites.","PeriodicalId":55353,"journal":{"name":"Bird Study","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136318440","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Declining territory occupancy and productivity in a Welsh Red-billed Chough <i>Pyrrhocorax pyrrhocorax</i> population","authors":"A. V. Cross, A. Stratford, I. Johnstone, P. J. Lindley","doi":"10.1080/00063657.2023.2264558","DOIUrl":"https://doi.org/10.1080/00063657.2023.2264558","url":null,"abstract":"ABSTRACT Capsule Much of the UK’s largest population of Red-billed Chough Pyrrhocorax pyrrhocorax shows long-term decline in territory occupancy and productivity. Underlying mechanisms need urgent study to improve conservation delivery for this species in Wales. Aims Periodic census data have shown a localized decline of Red-billed Choughs in Wales, which supported 66% of the UK breeding population in 2014. The aim is to explore the nature of this decline using long-term study data to search for patterns in territory occupancy and breeding performance. Methods Data from annual monitoring of breeding territories in mid- and north Wales, across 25 years and representing 74% of the Welsh population, were analysed to test for variation in occupancy and breeding metrics in relation to territory type, geographic region, and protection status. Results Most territories were coastal, where occupancy fell by 12%. Occupancy of inland territories fell by 72%, accounting for just 24% of territories by 2019. The number of chicks fledged per occupied territory fell by 25% across all territories, but the brood size of successful pairs only fell 9% with neither varying by territory type. Nest success rate fell 17% on the coast but 33% inland. Trends in occupancy and breeding metrics showed little variation between geographic regions and protection status. Conclusion The severe decline of inland nesting Red-billed Choughs could lead to rapid local extinction, but the slower decline in the coastal population is also of concern. Declining breeding performance is a plausible driver of population decline. As current conservation delivery appears ineffective, the mechanism of decline needs urgent study to identify necessary protection measures.","PeriodicalId":55353,"journal":{"name":"Bird Study","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135169884","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Habitat selection of breeding Wood Sandpipers <i>Tringa glareola</i> in Scotland","authors":"Bozena Kalejta-Summers","doi":"10.1080/00063657.2023.2260964","DOIUrl":"https://doi.org/10.1080/00063657.2023.2260964","url":null,"abstract":"ABSTRACTCapsule The European breeding population of the Wood Sandpiper Tringa glareola is estimated to be stable, but the species has declined in several countries. Describing breeding habitat requirements is important for the conservation and management of the breeding sites.Aims To determine the habitats used by breeding Wood Sandpipers.Methods Two breeding sites of Wood Sandpipers in Highland Scotland were visited regularly during spring and summer in 2006 and 2007; habitat variables were measured at points where birds were detected and compared with random points.Results The birds selected sites with a greater percentage of water cover, bare ground and Carex spp., but with a low index of total obscurity of vegetation.Conclusion By selecting habitat with bare ground, low obscurity of vegetation and shallow water, birds may have sufficient concealment from predators, but also maintain vigilance and obtain good feeding opportunities for themselves and their chicks. AcknowledgementsThe Royal Society for the Protection of Birds (RSPB), Scottish Natural Heritage (SNH) and Forestry Commission Scotland (FCS) made this project possible by providing financial support. I thank R. Summers for his comments on the manuscript and help with statistical analysis, and K. Chisholm for her invaluable help with all the logistics of the project. The owners of the local estates gave their support and permission to conduct this project on their land.Disclosure statementNo potential conflict of interest was reported by the author(s).","PeriodicalId":55353,"journal":{"name":"Bird Study","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135617834","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Wintering Great White Egrets <i>Ardea alba</i> in a riverine area in the Netherlands: numbers, abundance and timing","authors":"Rob Lensink, Paul van Els","doi":"10.1080/00063657.2023.2264559","DOIUrl":"https://doi.org/10.1080/00063657.2023.2264559","url":null,"abstract":"ABSTRACTCapsule The riverine area in the Netherlands is an important wintering area for Great White Egrets Ardea alba. Numbers decline in relation to very cold weather, and increase in relation to peaks in population cycles of Common Vole Microtus arvalis.Aim To analyse the variation in abundance and timing of wintering Great White Egrets between years and roosts.Methods The study area was a 21,000 ha section of the riverine area between the rivers Meuse and Waal. The paper presents the results of eight years of weekly counts of three roosts, one year of 10 roosts and seven years of nearly daily counts of foraging birds in an agricultural landscape. All surveys were carried out outside the breeding season.Results Birds used the area from the end of June until the beginning of April. Abundance strongly varied with small rodent prey availability, with maxima between 15 and 50 birds in years with average prey abundance, and a maximum of 125 individuals in 2019/2020 when prey availability was high. Since most birds foraged on grassland, this suggests a density of two birds per 100 ha in normal years and eight birds per 100 ha in peak years. Each roost covers a foraging area of 2000 ha in total, or 1000 ha grassland. Mean densities were similar between years but there was seasonal variation, with most roost counts peaking during autumn. Birds would temporarily leave the area during spells of snow or frost. In spring, departure towards the breeding grounds was partly dependent on the mean temperature in March.Conclusion Counts of Great White Egrets at roosting and foraging sites in the Netherlands vary seasonally with temperature and prey availability. AcknowledgementsThanks to the conservation organisations Gelders Landschap & Kastelen (André Bonte) and Staatsbosbeheer (Tymen van Heerde) for permission to do field work on their properties. Thanks to Ecco Smit and Roy Sluis, who participated in the counts at Ewijk and Wezelse Plas, and to Ton Ebben for doing counts during my holidays. Also thanks to Astrid Potiek for her critical review of an earlier draft and Job de Jong for preparing the map and calculating land use in Maas & Waal (both Bureau Waardenburg).Disclosure statementNo potential conflict of interest was reported by the author(s).","PeriodicalId":55353,"journal":{"name":"Bird Study","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135617024","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}