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We assessed annual changes in Eurasian Curlew Numenius arquata wintering numbers at estuaries in England and Wales over 40 years against local and broadscale factors. Long-term trends likely reflect the cessation of hunting, but potentially also distributional changes associated with milder winters and changes in breeding success. To investigate whether local or broadscale factors might affect site-level annual abundance changes in Curlews in England and Wales. Relationships between Wetland Bird Survey (WeBS) counts from 46 estuaries from 1974/75 to 2016/17 and environmental data were assessed using Generalized Linear Mixed Models. The winter abundance trend of Curlews in England and Wales closely matched the decline of breeding populations since the mid-1990s. However, there are clear differences in the trends prior to this. Our analysis suggests that winter counts were influenced by the cessation of hunting and by weather, with abundance decreasing during cold winters and increasing the following winter. The influence of severe weather was less pronounced in the immediate aftermath of the hunting ban. An increase in numbers in the east of the UK also occurred during this period. No effects were detected for other environmental variables, but this may reflect the fact that only static variation between sites was tested for these variables rather than change. The increase in wintering Curlew numbers in the UK during the 1980s and early 1990s likely reflects a positive response to the cessation of hunting, but also a wider redistribution associated with milder winters across the European wintering range. Winter temperatures influenced annual abundance changes at individual sites, although impacts on detectability are difficult to disentangle from impacts on survival using WeBS counts alone. Factors operating during the breeding season are likely to be the main drivers of the current population decline. [ABSTRACT FROM AUTHOR]

Capsule: The 2007 national survey of the UK breeding population of Little Ringed Plovers shows a further spread into Scotland and Wales since the previous survey in 1984. In contrast, there has been a significant decrease in the Ringed Plover breeding population. Aims: To provide new breeding population estimates in the UK and Great Britain for Little Ringed Plover Charadrius dubius and Ringed Plover Charadrius hiaticula in 2007 and investigate changes in breeding distribution and habitat use since 1984. Methods: Breeding population estimates were made by combining counts of pairs from 'key sites' (2 × 2 km tetrads known to be occupied in/since 1984) and estimates of the numbers of pairs away from these sites based on stratified sampling. Survey periods for Little Ringed Plover: 15 April to 15 July, three visits; Ringed Plover: 15 April to 30 June, two visits. Results: Population estimates, for 2007, of 1239 (95% confidence intervals: 1175–1311) pairs of Little Ringed Plover and 5291 (5106–5478) pairs of Ringed Plovers were calculated for Great Britain, with 5438 (5257–5622) pairs of Ringed Plover estimated in the UK. Counts of Ringed Plover at inland and coastal sites, covered in both 1984 and 2007, decreased by 83% and 53%, respectively. The Little Ringed Plover population has expanded in range northward and westward since 1984. Main habitats used in 2007 by Little Ringed Plover were inland gravel and sand (25.9%) and river shingle (17.8%); and, for Ringed Plover, coastal shingle and sand (38.5% and 13.7%, respectively) and machair plus associated habitats (23.8%) in the Outer Hebrides. Conclusions: Between 1984 and 2007, the Little Ringed Plover breeding population in the UK increased considerably, expanding northward and westward, with increased use of river shingle habitats. During the same period Ringed Plover breeding numbers in the UK declined considerably in both coast and inland habitats, likely to be due to human disturbance and habitat change, respectively. [ABSTRACT FROM AUTHOR]

Many emerging methods for ecological monitoring use passive monitoring techniques, which cannot always be used to identify the observed species with certainty. Digital aerial surveys of birds in marine areas are one such example of passive observation and they are increasingly being used to quantify the abundance and distribution of marine birds to inform impact assessments for proposed offshore wind developments. However, the uncertainty in species identification presents a major hurdle to determining the abundance and distribution of individual species., Using a novel analytical approach, we combined data from two surveys in the same area: aerial digital imagery that identified only 23% of individuals to species level and boat survey records that identified 95% of individuals to species level. The data sets were analysed to estimate the effects of environmental covariates on species density and to produce species-specific estimates of population size., For each digital aerial observation without certain species identification, randomized species assignments were generated using the observed species proportions from the boat surveys. For each species, we modelled several random realizations of species assignments and produced a density surface from the ensemble of models. The uncertainty from each stage of the process was propagated, so that final confidence limits accounted for all sources of uncertainty, including species identification., In the breeding season, several species had higher densities near colonies and this pattern was clearest for three auk species. Sandeel density was an important predictor of the density of several gull species., Synthesis and applications. This method shows it is possible to construct maps of species density in situations in which ecological observations cannot be identified to species level with certainty. The increasing use of passive detection methods is providing many more data sets with uncertain species identification and this method could be used with these data to produce species-specific abundance estimates. We discuss the advantages of this approach for estimating the abundance and distribution of birds in marine areas, particularly for quantifying the impacts of offshore renewable developments by making the estimates derived from the older digital surveys more comparable to the recently improved surveys. [ABSTRACT FROM AUTHOR]

CapsuleThe UK supported over 3.8 million wintering gulls in 2003/04–2005/06. AimsTo provide new winter population estimates for Great Britain, its constituent countries, Northern Ireland, Channel Islands and Isle of Man, for five species of gull. MethodsObservers undertook counts of gulls at roosts across three winters. Population estimates were produced by combining counts from key inland and coastal sites and estimates derived from stratified random sampling of inland tetrads and coastal stretches. ResultsOver 3.8 million gulls were estimated to winter in the UK and its near-shore coastal waters, a total that, due to more comprehensive methods, adds appreciably to previous estimates. Results inform conservation listings and required site-based conservation measures. Twenty sites held internationally important numbers of individual species and 37 internationally important assemblages and provisionally could qualify as Special Protection Areas for gulls alone. Forty-nine sites held nationally important numbers of particular species and provisionally could be notified as Sites/Areas of Special Scientific Interest solely for their importance for gulls. ConclusionsGiven the importance of the UK for wintering gulls and the declining status of some species, there is a clear requirement to consider measures and information needs that would provide for their conservation. [ABSTRACT FROM PUBLISHER]

Aim British estuarine ecosystems support large populations of protected migratory waders. Understanding how wader communities vary spatially and how they may be changing temporally can greatly improve the understanding of these dynamic ecosystems. Here, we explore the variation in functional diversity (using a range of morphological and ecological traits) in order to identify the processes shaping wader communities on British estuaries and how these processes may be changing. Location England, Wales and Scotland. Methods We use national survey data (Wetland Bird Survey) from 1980/1981 to 2006/2007 winter to calculate functional diversity (FD) - an index that measures trait dispersion - in wader communities on 100 estuaries. We test for evidence of non-random patterns of diversity and explore the relative importance of two key processes, environmental filtering and competition, in shaping these communities. Results The observed FD was significantly and positively associated with species richness and to a lesser extent estuary area, followed by longitude. An increase in observed FD was observed since 1980, supported by a small but significant slope. In the majority of cases, changes in FD were mirrored by changes in species richness. Observed FD was on average lower than expected by chance, as indicated by a negative value of observed minus expected FD. However, this difference became less negative over time, with observed minus expected FD values increasing slightly, but significantly, over the study period. Main conclusions Wader FD varies across British estuaries, and the relative influence of the processes by which communities are structured appears to be changing through time. We discuss the potential drivers underlying these patterns and the importance of identifying such drivers for the protection of wader communities. [ABSTRACT FROM AUTHOR]

Capsule Winter Gull Roost Survey data spanning 50 years were used to generate population indices. Aims To evaluate how wintering numbers of five gull species have changed in Great Britain over the last five decades. Methods Generalized linear models were used to relate gull numbers to habitat, site and year factors, and so derive species-specific indices for nine regions of Great Britain. Regional models considered data from different timescales depending on coverage. Results Patterns of change varied by species and region. All species showed increases in number over the period 1953 to 2004. In most regions, Black-headed Gull Chroicocephalus ridibundus numbers have declined since peaks between 1973 and 1993; Common Gulls Larus canus have also declined recently in some regions. Lesser Black-backed Gull L. fuscus numbers have increased dramatically since 1953, whereas numbers of Herring Gull L. argentatus showed large declines between 1963 and 1983. Great Black-backed Gull L. marinus numbers have increased in the west and the Midlands, but recently declined in eastern regions. Conclusions Numbers of wintering gulls in Great Britain have shown rapid changes over the last five decades, reflecting changes in the sizes of breeding populations. These changes are likely to be associated with changes in human activities and resource availability. [ABSTRACT FROM AUTHOR]

Detecting coherent signals of climate change is best achieved by conducting expansive, long-term studies. Here, using counts of waders ( Charadrii) collected from ca. 3500 sites over 30 years and covering a major portion of western Europe, we present the largest-scale study to show that faunal abundance is influenced by climate in winter. We demonstrate that the ‘weighted centroids’ of populations of seven species of wader occurring in internationally important numbers have undergone substantial shifts of up to 115 km, generally in a northeasterly direction. To our knowledge, this shift is greater than that recorded in any other study, but closer to what would be expected as a result of the spatial distribution of ecological zones. We establish that year-to-year changes in site abundance have been positively correlated with concurrent changes in temperature, but that this relationship is most marked towards the colder extremities of the birds' range, suggesting that shifts have occurred as a result of range expansion and that responses to climate change are temperature dependent. Many attempts to model the future impacts of climate change on the distribution of organisms, assume uniform responses or shifts throughout a species' range or with temperature, but our results suggest that this may not be a valid approach. We propose that, with warming temperatures, hitherto unsuitable sites in northeastern Europe will host increasingly important wader numbers, but that this may not be matched by declines elsewhere within the study area. The need to establish that such changes are occurring is accentuated by the statutory importance of this taxon in the designation of protected areas. [ABSTRACT FROM AUTHOR]

Capsule There has been a decline in the numbers of waterbirds wintering in Ireland between 1 994/95 and 2003/04, including a 5% decline in wildfowl and an 11% decline in waders. Aims To provide estimates of numbers and trends in relative abundance of selected waterbird species wintering on the island of Ireland. Methods Waterbird counts were undertaken at key wetland sites in Ireland each winter (September to March) between 1 994/95 and 2003/04. For each species, estimates were calculated for two five- season periods (1994/95-1998/99 and 1999/2000-03/04), while trends in relative abundance were analysed over the entire ten-season period. Counts were modelled using a multiplicative log-linear index model, with site, year and month factors. Results National estimates of overwintering numbers were produced for 42 species of waterbirds, and used to produce all-Ireland 1% thresholds (which are used to evaluate the importance of wetland sites). In winter, large proportions of several populations occur in Ireland, particularly Whooper Swan Cygnus cygnus, Greater White-fronted Goose (Greenland race) Anser albifrons flavirostris, Brent Goose (Canadian Light-bellied race) Branta bernicla hrota and Black-tailed Godwit Limosa limosa islandica. Of the 39 species for which trends were measured, 1 8 showed annual declines in excess of 2%, while ten species had increased. Numbers of the remaining 11 species were relatively stable. For many species, the trends measured appear to be continuations of longer-term changes since the 1970s. Conclusion These most recent estimates of waterbird numbers have been improved compared with those previously generated, due to improved levels of coverage and better analytical methods. This study highlights that there have been significant changes in the numbers of waterbirds wintering in Ireland over the past 30 years. The fact that many of these trends parallel wider flyway-scale population trajectories implies that large-scale drivers (e.g. climate change) may be responsible. However, many of the observed declines are likely to be a consequence of increased economic development which has led to direct habitat loss to industrial and residential development. [ABSTRACT FROM AUTHOR]

Capsule Both populations are increasing at a similar rate. Aims During 2000, an extensive survey of introduced Greater Canada Geese and re-established Greylag Geese in Great Britain was undertaken in order to update population estimates last made between 1988 and 1991. Methods A randomized stratified sample of 1 329 of the 61 51 0 tetrads (2 km x 2 km unit) in Great Britain was surveyed. The habitat categories, or strata, were based on the proportion of water cover, urbanization, and upland/lowland in each tetrad. Non-urbanized strata were further divided into northern and southern reporting areas. Results In 2000 there were an estimated 88 866 full-grown Greater Canada Geese and 24 522 full- grown Greylag Geese in Great Britain. Since the 1988-9 1 survey, Greater Canada Geese have increased by 166% and Greylag Geese by 1 70%, an average per annum rate of increase of 9.3% for Greater Canada Geese and 9.4% for Greylag Geese. The increase in Greater Canada Goose numbers since the 1988–91 survey has occurred mainly in habitats which had previously held low goose population densities, particularly the ‘no water ’ lowland habitat. Although densities were still relatively low in this habitat (<0.5 geese per km2), because of its extent it supported 56% of the total Greater Canada Goose population in 2000. The greatest increase in re-established Greylag Goose numbers has arisen from an expansion into lowland habitat with some water cover. Conclusion There was no obvious decline in the 8.3% per annum Greater Canada Goose growth rate that caused the population to treble. between 1976 and 1991. Greylag Goose numbers are increasing at a similar rate to those of the Greater Canada Goose. [ABSTRACT FROM AUTHOR]

Capsule The winter distribution of Golden Plover and Lapwing has shifted east since the mid-1980s, perhaps in response to climate change. Aims To combine analyses of winter trends on wetlands and flocks on farmland to assess the current status of Golden Plover and Lapwing in one of their main wintering regions. Methods Winter trends were derived from monthly counts on estuaries and wetlands for the period 1 974-2002 (the Wetland Bird Survey). Winter distribution on farmland was assessed using casual records of large flocks and surveys of a stratified random sample of 1-km squares (the Winter Farmland Bird Survey). Results Regional trends showed a pronounced increase in numbers of both species since i 974 on the east coast, with a smaller increase on the south coast. Numbers in the west and north tended to decline. Flocks on farmland were concentrated in eastern Britain unlike the situation in the 1980s. Conclusions The winter distribution of Golden Plover and Lapwing has shifted to the east, resulting in large numbers on the east coast and in the arable east of Britain. The implications of this shift, especially in relation to known habitat associations, are discussed. [ABSTRACT FROM AUTHOR]

Capsule Population size estimates of widely dispersed waterbird species in Great Britain were improved using a stratified random sample of habitats in addition to standard counts of known wetlands. Aims To improve the estimation of national population sizes for species less well covered by the UK Wetland Bird Survey (WEBS) using a stratified random sampling approach. Methods Observers recorded habitat type and waterbird numbers within a stratified random sample of 1-km grid squares across Great Britain. For 20 species, population sizes were estimated using boot-strap techniques. These totals were added to WeBS Core Count and Non-Estuarine Coastal Waterbird Survey (UK-NEWS) data and the resulting Dispersed Waterbird Survey (DWS) estimate compared with published national population estimates. Results DWS estimates exceeded published national estimates by more than 50% for eight species but were lower for Pochard Aythya farina, Goldeneye Bucephala clangula and Moorhen Gallinula chloropus. Conclusions Our analyses suggest that the DWS provides a useful source of supplementary information for several dispersed species and demonstrates the value of a stratified random sampling approach for monitoring waterbird populations. [ABSTRACT FROM AUTHOR]

The distributions of eight out of nine common species of waders (Charadrii) overwintering on UK estuaries have changed in association with recent climate change. These birds represent a high proportion of various populations from breeding grounds as far apart as Greenland to the west to high-arctic Russia to the east. During warmer winters, smaller proportions of seven species wintered in south-west Britain. The distributions of the smaller species show the greatest temperature dependence. The opposite was found for the largest species and no relationship was found for a particularly site-faithful species. In north-west Europe, the winter isotherms have a broadly north to south alignment, with the east being colder than the west. The average minimum winter temperatures across the UK having increased by about 1.5°C since the mid-1980s, the temperatures on the east coast during recent winters have been similar to those of the west coast during the mid-1980s. On average, estuaries on the east and south coasts of Britain have muddier sediments than those on the west coast and thus support a higher biomass of the invertebrate prey of waders. We suggest that, with global climatic change, the advantage gained by waders wintering in the milder west to avoid cold weather-induced mortality is diminished. Consequently, more choose to winter in the east and thus benefit from better foraging opportunities. The implications of these results are considered in terms of a site-based approach to wildlife protection used in Europe and elsewhere. [ABSTRACT FROM AUTHOR]

The relationship between weather and wader distributions on non-estuarine coasts is described and used to predict how future wader distributions may respond to climate change. The distributions of eight out of nine species of wader commonly wintering on the non-estuarine coasts of Britain altered between two similar surveys, in 1984/85 and 1997/98, that covered 78% and 38% of Britain's 12 594 km of non-estuarine coastline, respectively. These eight species moved at least in part either eastwards along the winter isotherms or northwards. These changes in distribution broadly coincide with a distributional shift towards the species’ respective breeding grounds and are correlated with the local winter weather over the period: increasingly mild extreme temperatures and changes in mean rainfall, mean wind speed and wind-chill. Based on the scenarios for Britain's climate in 2020 and 2080, it is predicted that the distributions of the waders will move away from the west. The non-estuarine coasts of Britain hold particularly high proportions of the international flyway populations of Ringed PloverCharadrius hiaticula, SanderlingCalidris alba, Purple SandpiperCalidris maritimaand Ruddy TurnstoneArenaria interpresthat are all expected to show continuing decline to 2080. Overwintering waders appear to be good indicators of the effects of climate change. [ABSTRACT FROM AUTHOR]

Capsule An updated estimate is presented and major declines in the internationally important populations of several species identified. Aim To provide population estimates of the waders overwintering on the UK and Isle of Man's nonestuarine 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): 70790 Oystercatcher Haematopus ostralegus (7%), 24 110 Ringed Plover Charadrius hiaticula (33%), 28670 Golden Plover Pluvialis apricaria (2%), 2175 Grey Plover Pluvialis squatarola (1%), 41 180 Lapwing Vanellus vanellus (1%), 7625 Knot Calidris canutus (2%), 13 660 Sanderling Calidris alba (11%), 17 220 Purple Sandpiper Calidris maritima (9%), 27 880 Dunlin Calidris alpina (2%), 3670 Bar-tailed Godwit Limosa lapponica (3%), 66330 Curlew Numenius arquata (16%), 33 820 Redshank Tringa totanus (18%) and 39 560 Turnstone Arenaria interpres (42%). Similarly the Isle of Man held 887 Ringed Plover (1%), 8895 Curlew (2%) and 5220 individuals of the other species. Conclusion Eight species have increased and five have declined in the UK since the 1984-85 survey. We discuss the possible reasons for the declines of Ringed Plover (-15%), Sanderling (-20%), Purple Sandpiper (-21%), Bar-tailed Godwit (-44%) and Turnstone (-16%), species whose numbers on the UK's non-estuarine coasts are internationally important. [ABSTRACT FROM AUTHOR]

Capsule Population change in geese was assessed using an approach that requires a relatively small sampling effort. Aims During the 1999 breeding season a survey was carried out to determine if the numbers of introduced Canada and re-established Greylag Geese in southern Britain had changed since 1988-91 and whether any change had occurred in areas with previously high or low Canada Goose densities. Methods A randomized stratified sample of 246 tetrads from the 24 156 tetrads covered between 1988-91 in this area, as part of the New Atlas of Breeding Birds, were resurveyed. Eight habitat categories were used in the stratification and were based on 1-km-square summary data obtained from the CEH Land Cover Map of Great Britain (water cover and urbanization) and LANDCLASS stratification (upland/lowland). The five habitat categories with the highest densities of Canada Geese and the greatest variance in numbers were sampled. Results Between 1989 and 1999, the number of Canada Geese on land with over 5% water cover and on lowland with some water cover increased by on average 156%, an average rate of increase of 9.9% per annum. Southern Britain probably now holds a minimum of 82 000 Canada Geese. Between 1989 and 1999, the number of Greylag Geese on land with over 5% water cover and on lowland with some water cover increased by on average 214%, an average rate of increase of 12% per annum. Southern Britain probably now holds a minimum of 30 000 Greylag Geese. Conclusion Maximum densities of Canada Geese may have been reached in high-density habitats but their numbers are still increasing very rapidly. Greylag Geese are increasing even more rapidly. [ABSTRACT FROM AUTHOR]

1. Predictive models of animal distribution based on habitat can be used to assess the likely effects of changes in landuse on a species. In this study we developed a model of the distribution of buzzard nests in part of Argyll, Scotland. the model was tested on a further study site. 2. Habitat was described in terms of vegetation cover, derived from satellite imagery, and topography, using a digital terrain model to classify altitude, slope, aspect and ruggedness. This data base was incorporated into a Geographical Information System. 3. Environmental data, in the form of areas and boundary lengths of vegetation types and landscape classifications, were extracted from the data base for circular areas of various radii from the centre of 500 m grid cells covering each study area. We also included counts of buildings and lengths of roadways. 4. Both logistic regression analysis and discriminant function analysis were used to produce classification models, which assigned each grid cell a probability that it contained a buzzard nesting area. the best predictive model was based on median altitude, total boundary length between all vegetation categories, the amount of moorland and the length of boundary between pre-thicket forestry and open ground. 5. This model successfully reclassified 96⋅88% of grid cells in the areas from which it was developed and 82⋅35% in a test area. Previous studies have frequently predicted the distribution of species within the environment, but here we were able to predict the distribution of nesting areas within the distribution of a species. [ABSTRACT FROM AUTHOR]

All ecological measurements are subject to error; the effects of missed detection (false negatives) are well known, but the effects of mistaken detection (false positives) are less understood. Long-term capture–recapture datasets provide valuable ecological insights and baselines for conservation and management, but where such studies rely on noninvasive re-encounters, such as field-readable color bands, there is the potential to accumulate detection errors as the length of the study and number of tags deployed increases. We investigated the prevalence and effects of misreads in a 10-yr dataset of Red Knots (Calidris canutus rufa) marked with field-readable leg flags in Delaware, USA. We quantified the effects of misreads on survival estimation via a simulation study and evaluated whether removal of individuals only reported once in a year (potential misreads) influenced survival estimation from both simulated datasets and our case study data. We found overall apparent error rates of 0.31% (minimum) to 6.6% (maximum). Observer-specific error rates and the variation among observers both decreased with the number of flags an observer recorded. Our simulation study showed that misreads lead to spurious negative trends in survival over time, particularly for long-term studies. Removing all records in which a flag was only recorded once in a sampling occasion reduced bias and eliminated spurious negative trends in survival but also reduced precision in survival estimates. Without data filtering, we found a slight decrease in Red Knot annual survival probability from 2008 to 2018 (β = −0.043 ± 0.03), but removing all single-observation records resulted in no apparent trend (β = −0.0074 ± 0.02). Spurious trends in demographic rates could influence inference about population trajectories and resultant conservation decision-making. Data filtering could eliminate errors, but researchers should carefully consider the tradeoff between precision obtained by larger sample sizes and potential bias due to misreads in their data. [ABSTRACT FROM AUTHOR]

Regional trends in the populations of waders wintering largely on estuaries were analysed using data collected by the Wetland Bird Surveybetween the winters of 1969/70 and 1995/96 to assess whether trends seen at the national level were repeated across regions of Britain. Not all were. Over this period, the numbers of seven of the 12 species studied increased in south and southeast England, but remained static or declined in southwest England and south Wales. Possible explanations for this are proposed. Increases in the number of Curlews Numenius arquata in the north and northeast of Scotland occurred after 1981/82, when the species stopped being a legal quarry species. A rapiddecline in Oystercatcher Haematopus ostralegus and Knot Cahdris eanutus numbers in east England after 1988/89 may be linked to a change in the Wash shell-fisheries. Warmer winters may be making it less essential for birds to winter in the milder west of Britain. In two pairsof regions, northeast and southeast Scotland, and in northwest England north Wales and northeast England, waders showed similar long-termpopulation changes. The long-term population trends of Oystercatchers in the different regions correlate to those of Ringed Plovers Charadrius hiaticula and Knot, while those of Ringed Plovers are very similar to those of Bar-tailed Godwits Limosa lapponica. In some regions of Britain, the population trends of some species varied a lot between sites, a factor that is an important consideration when determiningthe size and geographical position of regions for future regional indexing. The present separation of regions based on water catchments and geography has given a useful insight into population changes at a finer spatial scale but it could be improved further with added biological input. [ABSTRACT FROM AUTHOR]