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Previous studies have highlighted the importance of intertidal habitats on the coast of Jiangsu Province, China for the Critically Endangered Spoon-billed Sandpiper Calidris pygmaea during the post-breeding moult. We report Lincoln-Petersen closed-population estimates of numbers of Spoon-billed Sandpipers Calidris pygmaea at the three principal sites in the region for the species: Tiaozini, Yangkou and Dongling. Our estimates were based upon resightings and scan surveys of individually-marked birds. Surveys were conducted in September–October when nearly all of the birds present were adults (≥1 yr old). We estimated the number present at Tiaozini in each of the years 2017–2020, during which numbers declined from 225 to 151, mostly between 2018 and 2019. To identify parts of the intertidal area used by Spoon-billed Sandpipers, we mapped locations of satellite-tagged birds in 2017 and 2019. Data from seven tagged birds indicated that they moved to intertidal flats up to 7 km seaward of the nearest point of the seawall at low tide. We then analysed satellite imagery for 2017–2020 for intertidal areas up to this distance from the coast and found evidence for changes in topography of the intertidal mudflats and positions of major channels. The mean extent of exposed mudflats per tidal cycle appeared to have declined by about 20% between 2017 and 2020. Surveys at two other sites in 2020 indicated that there were 26 birds at Yangkou and 63 birds at Dongling, with a total of 240 birds at all three sites combined in 2020. This is approximately half of the estimated world population of adults. The coast of Jiangsu Province is therefore of global importance for the Spoon-billed Sandpiper. Although birds no longer at Tiaozini may have been displaced to other sites, the observed population decline, which co-incided with changes in intertidal topography, raises concerns about the future conservation status of the species. Uncertainty about future changes to the topography and extent of intertidal mudflats makes the co-ordinated protection of all sites in Jiangsu Province known to hold Spoon-billed Sandpipers during the post-breeding moult period a conservation priority. This applies particularly to Tiaozini, Yangkou and Dongling, but also to other sites at which future surveys may reveal to hold concentrations of the species.

A single formal estimate of the size of the world population of the Critically Endangered Spoon-billed Sandpiper Calidris pygmaea has been published. This used a Lincoln-Petersen method, which combined a global mark-resighting analysis with a scan survey to estimate the proportion of birds with individual marks observed at a post-breeding moult and migration stopover site in Jiangsu Province, China. We report nine further repetitions of this procedure, which we call Method A, giving ten world population estimates in all, during the 6-year period 2014–2019. Four of these estimates use scan surveys from Jiangsu in the post-breeding adult moult period and six are from the non-breeding season (November–February) at three widely-separated sites in Bangladesh, Myanmar and South China. The weighted mean world population size at the end of the breeding season, based upon all ten surveys, was 490 mature individuals (95% C.L. 360–620) and 773 individuals of all ages (95% C.L. 569–978), which is similar to the single previous Method A estimate (420 mature individuals), but considerably more precise. We also report results from two independent but low-precision methods: one based upon published non-breeding season counts and the non-breeding season localities of satellite-tagged birds (Method B) and the other based upon mark-recapture analysis of birds marked as unfledged chicks and recaptured as migrating juveniles (Method C). These two methods gave estimates within the range 471 to 922 mature individuals, depending upon assumptions. The trend of Method A population size estimates with time during the short study period was a decline at a mean rate of 8% per year, but this did not differ significantly from zero (no change). The precision of this estimate of population trend was low, but its rate is of similar magnitude to the 9% per year decline during 2009–2016, derived from surveys of the local population at the most important known non-breeding season site in Myanmar. Hence, although the rapid population decline indicated by surveys of breeding populations observed prior to 2009 (mean 26% decline per year) has probably slowed as a result of conservation efforts, our results indicate that the species should continue to be listed as Critically Endangered.

SummaryThe Spoon-billed Sandpiper Calidris pygmaea is a ‘Critically Endangered’ migratory shorebird. The species faces an array of threats in its non-breeding range, making conservation intervention essential. However, conservation efforts are reliant on identifying the species’ key stopover and wintering sites. Using Maximum Entropy models, we predicted Spoon-billed Sandpiper distribution across the non-breeding range, using data from recent field surveys and satellite tracking. Model outputs suggest only a limited number of stopover sites are suitable for migrating birds, with sites in the Yellow Sea and on the Jiangsu coast in China highlighted as particularly important. All the previously known core wintering sites were identified by the model including the Ganges-Brahmaputra Delta, Nan Thar Island and the Gulf of Mottama. In addition, the model highlighted sites subsequently found to be occupied, and pinpointed potential new sites meriting investigation, notably on Borneo and Sulawesi, and in parts of India and the Philippines. A comparison between the areas identified as most likely to be occupied and protected areas showed that very few locations are covered by conservation designations. Known sites must be managed for conservation as a priority, and potential new sites should be surveyed as soon as is feasible to assess occupancy status. Site protection should take place in concert with conservation interventions including habitat management, discouraging hunting, and fostering alternative livelihoods.

The spoon-billed sandpiper Calidris pygmaea, a migratory Arctic-breeding shorebird, is one of the rarest birds and its population has declined since the 1970s. We surveyed its most important known wintering area in the Upper Gulf of Mottama in Myanmar to estimate recent (2009–2016) changes in its numbers there. The total number of small shorebirds present in the Upper Gulf was counted and the proportion of them that were spoon-billed sandpipers was estimated from sample scans. These two quantities were multiplied together to give the estimated number of spoon-billed sandpipers in each of 4 years. Total numbers of combined small shorebird species tripled from 21,000 to 63,000 between 2009 and 2016, coincident with efforts to reduce hunting pressure on waterbirds. However, the proportion of small shorebirds that were spoon-billed sandpipers declined and their estimated absolute numbers fell by about half, from 244 to 112 individuals. It is probable that loss of intertidal habitat and shorebird hunting elsewhere on the migration route of the spoon-billed sandpipers wintering at Mottama is causing a continued decline, although this is occurring at a less rapid rate than that recorded from Arctic Russia before 2010. The number of spoon-billed sandpipers wintering on the Upper Gulf of Mottama remains the highest single-site total for this species from any known wintering site. Preventing resurgence of illegal shorebird hunting and ensuring long-term protection of the intertidal feeding habitats and roost sites in the Gulf are high priorities if extinction of this species is to be averted.

SummaryThe Yellow Sea region is of high global importance for waterbird populations, but recent systematic bird count data enabling identification of the most important sites are relatively sparse for some areas. Surveys of waterbirds at three sites on the coast of southern Jiangsu Province, China, in 2014 and 2015 produced peak counts of international importance for 24 species, including seven globally threatened and six Near Threatened species. The area is of particular global importance for the ‘Critically Endangered’ Spoon-billed Sandpiper Calidris pygmaea (peak count across all three study sites: 62 in spring [2015] and 225 in autumn [2014] and ‘Endangered’ Spotted Greenshank Tringa guttifer (peak count across all three study sites: 210 in spring [2014] and 1,110 in autumn [2015]). The southern Jiangsu coast is therefore currently the most important migratory stopover area in the world, in both spring and autumn, for both species. Several serious and acute threats to waterbirds were recorded at these study sites. Paramount is the threat of large-scale land claim which would completely destroy intertidal mudflats of critical importance to waterbirds. Degradation of intertidal mudflat habitats through the spread of invasive Spartina, and mortality of waterbirds by entrapment in nets or deliberate poisoning are also real and present serious threats here. Collisions with, and displacement by, wind turbines and other structures, and industrial chemical pollution may represent additional potential threats. We recommend the rapid establishment of effective protected areas for waterbirds in the study area, maintaining large areas of open intertidal mudflat, and the urgent removal of all serious threats currently faced by waterbirds here.

In the North Sea, sandeels provide a vital food source for breeding seabirds, but are also the target of an industrial fishery. GPS tracking suggests that the most productive fishing grounds overlap with foraging areas of black-legged kittiwakes from eastern England, raising the prospect that the fishery could affect the birds. Rising sea temperatures also threaten sandeels, so kittiwake food supplies could be affected by local and larger-scale processes. Drivers of kittiwake breeding success at Flamborough Head and Bempton Cliffs Special Protection Area, the UK's largest colony, and one of the closest to the sandeel fishing grounds, were examined. Relationships between sandeel stocks, sea surface temperature and kittiwake breeding success were analysed with generalized linear mixed models and generalized linear models, with model performance assessed using the Akaike Information Criterion and R2. Higher kittiwake breeding success was associated with higher sandeel spawning stock biomass (SSB; biomass of sexually mature fish) the preceding winter (R2 = 21.5%) and lower sandeel fishing mortality two years previously (R2 = 22.3%). After temporal trends were removed, only the fishing mortality effect remained. Models with multiple predictors supported the importance of fishing mortality. Higher sandeel SSB was associated with lower temperatures (R2 = 15.2–38.6%) and lower sandeel fishing mortality (R2 = 24.2–26.1%). Hence, lower temperatures and fishing mortality were positively associated with sandeel biomass, and higher sandeel biomass and lower fishing mortality were positively associated with kittiwake productivity. In light of worsening environmental conditions and declining sandeel and kittiwake populations, careful consideration should be given to the requirements of sandeel-dependent predators when making fishery management decisions.

The spoon-billed sandpiper Calidris pygmaea is a Critically Endangered shorebird that breeds in the Russian arctic and winters in coastal and estuarine habitats in South-east Asia. We report the first formal estimate of its global population size, combining a mark–resighting estimate of the number of leg-flagged individuals alive in autumn 2014 with an estimate of the proportion of birds with flags from scan surveys conducted during the same period at a migration stop-over site on the Jiangsu coast of China. We estimate that the world breeding population of spoon-billed sandpipers in 2014 was 210–228 pairs and the post-breeding population of all age classes combined was 661–718 individuals. This and related methods have considerable potential for surveillance of the population size of other globally threatened species, especially widely dispersed long-distance migrants.

1.The cirl bunting (Emberiza cirlus L.) has been the subject of targeted and successful conservation efforts based on agri-environment schemes (AES) in the UK since 1993. Recent work has suggested that although focused on a single species, there have been wider biodiversity benefits for plants and some invertebrates. 2.In this study we investigated whether a similar pattern could be found for the Auchenorrhyncha (plant- and leafhoppers) within agricultural grasslands, where they form an important component of the herbivore community. 3.Sweep netting was used to sample Auchenorrhyncha from AES pastures, on which no pesticide or fertiliser inputs are allowed, and from conventionally grazed and cut (silage) fields at 25 locations in south Devon UK, during 2008. 4.Generalised linear mixed models and non-metric multidimensional scaling were used to model abundance, species density, and community structure. 5.AES fields had the highest abundance, followed by conventionally grazed and then cut fields. The same pattern occurred for species density, although there was no significant difference between conventionally grazed and cut fields. There was no difference in community structure between field types. 6.Number of plant species, sward age, and nitrogen input were important covariates of field type, suggesting that the limitations on inputs resulting from AES are the likely drivers of the observed differences. 7.The results add to the evidence base that suggests that increased agricultural intensity is inversely related to invertebrate biodiversity. They also provide evidence that AES designed for the cirl bunting have provided wider biodiversity benefits.

Capsule Summer bird densities in establishment-stage (2–3-year-old) Miscanthus were the same as in winter wheat fields for many species, but were higher for Lapwing, and for Reed Bunting and Blackbird late in the summer. Aims To compare abundances of farmland birds in establishment-stage Miscanthus biomass crops with those in crop types they are likely to replace (winter wheat and grassland) during the breeding season. In particular, to investigate whether such a rapid-growing, dense crop has lower abundances of field-nesting species. Methods Bird surveys were conducted in 51 Miscanthus fields and an equal number of grass or winter wheat control fields between May and July, in Lincolnshire and southwest England. Results Species richness was similar in Miscanthus to that in winter wheat and grass. Skylark densities were similar in Miscanthus and wheat, while Lapwing densities were higher in Miscanthus and grass than wheat. Miscanthus contained very high densities of Reed Buntings and Blackbirds late in the...

Capsule Yellow Wagtails successfully raised two consecutive broods in landscapes dominated by autumn-sown crops and did not require spring crops or fallow plots for later nesting. Aims To assess whether arable landscapes dominated by winter cropping provide habitats that allow Yellow Wagtails to raise two successful broods. To assess the utility of spring cultivated agri-environment fallow plots as a nesting and foraging habitat for Yellow Wagtails. Methods Nesting success and foraging behaviour of Yellow Wagtails was monitored on lowland arable farmland dominated by winter cropping during two successive breeding seasons. Results Yellow Wagtails successfully raised first and second broods mainly in winter cereals, with later nests being more successful. Some nests were initiated in bean fields where egg-stage failure rates were high, probably as a consequence of depredation. Fallow plots were not used for nesting but, along with other areas of sparse vegetation, were regularly used for foraging. Conclusio...

This study tested whether agri-environment scheme (AES) management for corncrakes in the UK is associated with higher diversity or abundance of non-target flora and fauna relative to similar land outside AES management. The species richness and abundance of forbs, butterflies, bumblebees and foliar arthropods were compared on 101 paired control-treatment plots across the two AES measures for corncrakes: provision of tall vegetation throughout the breeding season (Early and Late Cover; ELC) and delayed mowing (DM) of hay or silage fields. There were significant positive effects of AES management for the species richness of forbs, and abundance of late-season flowers, butterflies, bumblebees and the majority of foliar arthropod groups on one or both AES measures. Significant negative effects of AES were found in only two cases: forb species richness (ELC only) and the abundance of springtails (DM only). For the remaining species and groups studied there was either no effect of AES or no clear difference due to strong AES × season interactions. The magnitude of the AES effects varied substantially both between taxonomic groups and the two measures for corncrake. Most of the positive effects were for common and widespread species, except for two rare bumblebees. The benefits resulted from the reduction in farmland management intensity associated with AES. While not beneficial to all taxonomic groups these results demonstrate that, in the case of corncrakes in the UK at least, well-designed AES measures targeted at a specific species do yield wider biodiversity benefits.

Two-hectare unsown, tilled fallow plots put in place under agri-environment schemes for stone curlews Burhinus oedicnemus in England were surveyed for other bird species, brown hares Lepus europaeus, carabid beetles, vascular plants, butterflies and bumblebees. The results were compared with those from surveys within the crop in the same field and in neighbouring fields. This was done to test whether agri-environment management targeted at a single species also provided benefits to wider biodiversity. All groups except carabid beetles were more abundant, more likely to be recorded, or more species rich on plots than within the crop. Carabid beetle activity–density and species richness did not differ between the plot and the crop; activity–density of one functional group (predators) was lower on plots than in the crop. Six rare arable plant species were recorded, predominantly from plots, and the plots are considered to perform comparably to other agri-environment options available in England designed specifically for arable plants. One red-listed bird species of conservation concern (skylark Alauda arvensis) was more abundant on plots than in the crop, and three other red-listed species (linnet Carduelis cannabina, yellowhammer Emberiza citrinella, corn bunting E. calandra) were more likely to be recorded on plots than in the crop. A fifth (lapwing Vanellus vanellus) was almost exclusively recorded from plots, and was more likely to be recorded on plots categorised as in good condition for stone curlews. These results demonstrate that fallow plots that have been put in place for the recovery of stone curlews have considerable value for a range of other farmland biodiversity, although management for stone curlews may be detrimental to some taxa, such as carabid beetles, that are sensitive to the relatively frequent spring tillage that these plots receive.

Agri-environment scheme (AES) management has increased populations of cirl buntings (Emberiza cirlus) in South Devon, England, and might be expected to provide benefits for other declining biodiversity, due to less intensive farm management. Fields managed under AES for cirl buntings (low-input spring barley or permanent pasture without inputs) were contrasted with control fields under conventional management (spring barley without management restrictions and winter cereals, or grazed without management restrictions) to identify such benefits for vascular plants, butterflies, bumblebees, carabid beetles, foliar invertebrates and bats. Activity-density and species richness of carabid beetles were both higher in AES spring barley fields than in control spring barley and winter cereal fields. Forb cover and abundance of butterflies and bumblebees were higher in AES spring barley fields than in winter cereals, but did not differ between AES and control spring barley. No difference was observed in plant species richness between any of the arable field types. Plant species richness and butterfly abundance were higher in AES pasture fields than in controls. Abundance, activity-density and/or species richness of other taxa did not differ between AES and control pastures. Benefits observed in AES spring barley fields arise from management specific to AES agreements, and also, we suggest, from the maintenance of spring-sown barley in the landscape. Benefits in AES pasture fields are ascribed to the absence of fertiliser and pesticide inputs, and reductions in stocking arising from this; there is also likely to have been some pre-selection for older pastures to be entered into AES management agreements. Agri-environment measures for cirl buntings have benefits for a range of taxa beyond the target species, and therefore, largely through reduction of management intensity and maintenance of land-use diversity, improve the overall biodiversity of the farmed landscape where they are present.

The potential for agri‐environment schemes to reverse farmland bird declines is limited for some species by a lack of suitable prescriptions, in particular effective in‐field options for species that breed in crops. We assess the provision of alternative nesting habitat for increasing productivity of the Corn Bunting Emberiza calandra. Breeding success was monitored over three years in response to a tailored option that provided extensively managed crops of spring‐sown barley, most of which were funded by existing agri‐environment schemes and were left unharvested. Corn Buntings nested in both extensively managed crop provisions and conventional intensively managed barley crops. Females that used extensively managed crops for first nesting attempts were almost four times more likely to re‐nest, despite their later onset of breeding, than females nesting in conventional crops. The latter rarely produced a second nest and, when they did, usually switched nesting habitat. Extensively managed cereal crops were strongly selected by breeding females and supported a high proportion of the breeding population. A re‐nesting model demonstrated that differential re‐nesting rates led to 26% higher annual productivity per female in extensively managed cereal crops. Scenario testing illustrated the importance of timely establishment and deferred harvest of these extensively managed cereals. We recommend the provision of unharvested, extensively managed cereal crops as an agri‐environment option for Corn Buntings where intensively managed cereal crops are the main nesting habitat.

Human-induced habitat changes often generate novel or radically altered habitat characteristics, which can impair the ability of organisms to differentiate between suitable and unsuitable sites. This phenomenon, often termed an ecological trap, has been identified as a potential driver of biodiversity loss worldwide. However, few unequivocal examples have been documented, even in agricultural environments where contemporary habitat changes have been rapid and significant. Several problems complicate the detection of ecological traps in the field, including difficulties in measuring key parameters such as relative habitat preference. Here, we assess habitat selection preferences and breeding success of the yellow wagtail Motacilla flava, a UK red-listed declining passerine, in arable farmland. We combine habitat-specific density indices with measures of home range exclusivity to make inferences on relative habitat preference that are robust to the confounding effect of competitive exclusion. Using multiple measures of breeding success, we identify maladaptive habitat selection patterns at the scale of both territory and nest site choice. Yellow wagtails showed a preference for establishing territories within field bean crops, but subsequently suffered high nest predation rates. Similarly, pairs showed a preference for nesting close to tramlines within cereal fields, but nests further from tramlines achieved higher success due to lower predation rates. We found no evidence of competitive exclusion among neighbouring pairs, suggesting that density-based indices provided an accurate reflection of relative habitat preferences. Our findings highlight the potential role of maladaptive habitat selection in suppressing breeding success among farmland species.

Stable isotope analysis of feathers can be useful in the study of seasonal interactions and migratory connectivity in birds. For the PalaearcticAfrican migration system, however, the lack of isotope data from feathers of known origin in Africa renders the geographic assignment of birds captured on European breeding grounds to potential wintering areas problematic. Rectrices of the threatened aquatic warbler Acrocephalus paludicola grown in Africa were sampled across six European countries to assess whether birds in different breeding populations shared similar isotopic signatures and so were likely to have wintered in the same region in Africa. Freshly grown feathers of aquatic warblers collected at the only known wintering site in Senegal showed high variation in carbon, nitrogen, and hydrogen isotope ratios. Due to similarly high variation in isotope ratios of African-grown feathers within all breeding populations, it was not possible to determine whether different populations wintered in different regions. However, isotope signatures of 20% of birds captured on European breeding grounds fell outside the range of those captured in Senegal, suggesting a wider wintering distribution than is currently known. We therefore assessed whether the origin of these feathers could be estimated by trying to establish isotopic gradients across sub-Saharan West Africa. Feathers of three ecologically similar surrogate species were sampled from wetlands across a 3000 km east-west and a 2000 km northsouth transect. Within-site variation in feather isotope ratios was frequently larger than the difference predicted by gradients across West Africa. Thus, predicting the origin of individual feathers using single-isotope gradients was not reliable. The large within-site variability of feather isotope ratios of a habitat specialist species like the aquatic warbler indicates that using feather isotope ratios will require large sample sizes from many locations, and may thus not be an efficient tool in identifying wintering areas of Palaearctic African migrants.

SummaryA small colony of Northern Bald Ibis Geronticus eremita breeding in the Syrian desert is the only wild remnant of the eastern population of this ‘Critically Endangered’ species. Since its discovery in 2002, the colony has not increased in size despite being protected on the breeding grounds and exhibiting good productivity until recently. Although it appears that the population is being limited during migration and/or wintering, maintaining maximum breeding productivity is a priority for saving this colony to offset poor survival away from Syria. The ibises have a large home range but forage at a relatively small number of sites within it, despite having access to larger areas of apparently suitable habitat. We sampled potential prey using transects, pitfall traps and searches under stones at sites used by the birds to compare with unused sites. Analysis showed that used sites were twice as rich in vertebrate and invertebrate prey than the surrounding areas. Prey levels halved over the course of the breeding season, but we found that they remained higher in the preferred locations compared with the unused areas. Sites closer to the breeding cliff tended to have lower levels of prey available, which perhaps explained the long commutes that the adults undertook when foraging.This work highlights the vulnerability of the birds at this site. Degradation of the patches they use could reduce food supply below critical levels and alternative sites may be hard for the birds to identify, being relatively scarce. The birds are also vulnerable to shortening of the season in which adequate food is available. There is already little time post-fledging to prepare for migration. Low food availability later in the season makes the birds dependent on key resources found around local reservoirs and these have failed recently. Breeding failures in 2008 and 2009 may have been mitigated by improved feeding conditions on the breeding area. The successful management of the site for ibises should include measures to improve their food security through range management, and possibly reservoir rehabilitation.

Declines in habitat quality through the breeding season within a bird's home-range can limit overall productivity. In environments where multiple breeding opportunities arise during the course of a season, these effects can be buffered by a shift to different breeding sites or habitats. We studied the distribution and habitat associations of a crop-nesting farmland bird, the Yellow Wagtail Motacilla flava, across an arable-dominated farming region in eastern England using both field-scale territory mapping and large-scale transect surveys. Surveys were repeated at monthly intervals to measure changes in both distribution and habitat use during the course of the season. The distribution of breeding birds changed markedly at both regional and field-scales, coinciding with a shift in crop preference. Initially, most territorial birds were recorded in autumn-sown cereal fields, but this crop was subsequently abandoned in favour of potato crops, which were more patchily distributed. Other habitat features influencing Yellow Wagtail distribution included local crop diversity, hedgerow presence and soil type, with organic soils supporting higher abundance than alluvial clays or silts. The mid-season switch in habitat associations might allow individuals to maximize the number of breeding attempts made in a single year by using multiple habitats sequentially. The use of multiple habitats could influence population regulation by buffering the effects of local within-season declines in habitat suitability. Seasonal habitat switching may be more prevalent than is currently recognized in seasonal environments.

Capsule Yellow Wagtails showed seasonally variable foraging preferences, favouring field margin and crop habitats, although habitat availability did not influence brood productivity. Aims To identify key habitats and prey types for Yellow Wagtails in arable farmland, assessing the importance of foraging habitat availability in determining breeding productivity. Methods Intensive nest searches were conducted across six areas in eastern England over two breeding seasons. Focal nest watches were used to determine foraging habitat selection. Nestling condition was analyzed in relation to surrounding habitat characteristics and weather conditions. Diet was assessed using chick faecal samples. Results Wet ditches and tracks were favoured foraging habitats, together with crop fields used for nesting. Crop preference varied seasonally, with autumn‐sown wheat preferred in May–June and potatoes preferred in July–August. Chick diet was dominated by flies (Diptera), although beetles (Coleoptera) were prevalent in ear...

Ringing has been an important research tool for the conservation biologist over the last 100 years. Effective conservation of wild bird populations requires understanding of bird ecology and of the factors driving population change, and evidence that proposed conservation measures can be effective. Bird‐ringing studies can provide a wide range of data types to aid and inform this process, and in many cases these data are not available without the capture and marking of individual birds. We review the range of information available from bird ringing, and illustrate this with case studies where ringing has made a key contribution to the knowledge and subsequent conservation action applied to a particular bird population. The value to bird conservation is typically higher where a ringing study is well designed and targeted to answer specific questions of relevance to conservation. Therefore, there is potential for the conservation value of ringing to be improved in future through the development and encourag...

Major changes to the extent and quality of farmland habitats, brought by the intensification of agricultural practice, are thought to be the main factors driving declines in a suite of farmland bird species in Europe. Recent changes in agricultural techniques have also contributed to widespread soil degradation, arising from increased soil exposure to erosion forces, declining soil organic content and increasing soil compaction. Although soils have a fundamental influence on ecosystem properties, the implications of soil degradation for farmland biodiversity have received little attention. In this study, we measure the influence of soil conditions on the distribution of a declining insectivorous farmland bird, the yellow wagtail Motacilla flava, relative to other habitat features in arable fields. Soil penetrability was found to have a significant influence on the abundance of territorial yellow wagtails at the field scale, together with crop type. Other measured habitat features had little effect on territory abundance, including soil organic content, crop height (within preferred crop types), field boundary habitats and availability of bare ground. Monitoring of invertebrate abundance across 20 cereal fields revealed a significant influence of both soil penetrability and soil organic content on aerial invertebrate capture rates. This relationship was strongest during the latter part of the breeding season, implying that settling yellow wagtails could use soil penetrability as a predictive indicator of prey abundance during the chick-rearing period. The strong relationship between yellow wagtails and soil penetrability suggests a potential causative link between soil degradation and population decline. The role of soils in determining abundance patterns and population declines of other farmland species may have been overlooked in previous studies.

Capsule Chick diet varies seasonally and between wet and dry habitats, and there is little evidence for a link between habitat type and productivity. Aim To examine the influence of habitat composition and diversity on Tree Sparrow productivity and nestling diet in a wide variety of locations across the UK. Methods Productivity, chick diet and habitat data were collected from Tree Sparrow nestbox colonies by volunteer bird-ringers in 2002. Nestling diet was assessed by identification of invertebrate remains in faecal sacs. Results Clutch size was significantly higher for Tree Sparrows breeding in farmland than for those in wetland colonies. This did not translate into increased productivity. There was no other evidence of any effect of habitat or nestling diet composition on annual productivity. Diet composition varied seasonally, with habitat type and between individual sites. Conclusions Tree sparrows are capable of successful breeding in a range of habitats, where they utilize a wide range of invertebr...

Capsule Avian predators are principally responsible. Aims To document the fate of Spotted Flycatcher nests and to identify the species responsible for nest predation. Methods During 2005–06, purpose-built, remote, digital nest-cameras were deployed at 65 out of 141 Spotted Flycatcher nests monitored in two study areas, one in south Devon and the second on the border of Bedfordshire and Cambridgeshire. Results Of the 141 nests monitored, 90 were successful (non-camera nests, 49 out of 76 successful, camera nests, 41 out of 65). Fate was determined for 63 of the 65 nests monitored by camera, with 20 predation events documented, all of which occurred during daylight hours. Avian predators carried out 17 of the 20 predations, with the principal nest predator identified as Eurasian Jay Garrulus glandarius. The only mammal recorded predating nests was the Domestic Cat Felis catus, the study therefore providing no evidence that Grey Squirrels Sciurus carolinensis are an important predator of Spotted Flycatcher n...

The UK population of the Spotted Flycatcher Muscicapa striata has declined markedly in the last 30 years but there have been few recent studies of the species. This study examined the relationship between nest success and the predominant habitat type around Spotted Flycatcher nests in two contrasting areas of England. A breeding population in eastern England, a region where numbers of Spotted Flycatchers are known to have decreased dramatically in recent decades, was compared with another in southwest England, where numbers have remained stable or even increased. Whilst there was no difference in breeding success between the two study areas, there were significant differences between habitats, with garden nests more successful than those in farmland or woodland, at both egg and chick stages. Estimates of productivity per nesting attempt were also lower in farmland and woodland, with nests in gardens fledging twice as many chicks as those in either woodland or farmland. The proximate cause of lower success in farmland and woodland was higher nest predation rates during both egg and chick stages. In terms of nesting success, farmland and woodland appear to be similar in quality for this species, but both appear to be suboptimal habitats when compared with gardens, providing evidence of a problem on the breeding grounds for this species, in at least these two habitats.

1. Low winter food availability is probably critical in the declines of many farmland bird species in Europe, leading to the implementation of ameliorative agri-environment scheme options. To date, however, there has been no experimental test of the effectiveness of such options. 2. We report the results of two large-scale, 3-year, controlled experiments investigating the effects of supplementary winter seed provision on breeding farmland bird abundance. In each experiment, the use of winter feeding sites by birds was monitored and the availability of alternative, seed-rich habitat in the surrounding area was measured. The Winter Food for Birds (WFFB) project also included variable levels of food provision. Breeding bird abundance was then monitored in experimental and control areas. The Bird Aid project targeted yellowhammer Emberiza citrinella L., corn bunting Emberiza calandra L. and tree sparrow Passer montanus L., while WFFB considered 11 species that used supplementary winter food. 3. Comparisons of trends in breeding abundance between experimental and control areas revealed little evidence for positive effects of feeding, but there was great variation in the use of feeding sites by each species, and therefore in the seed quantity birds received. 4. Declines for yellowhammer, robin and dunnock were less steep where more food was provided in WFFB areas (a fourfold difference in seed provision across 1·5 times the land area). 5. Analysing trends with respect to weight-of-use of winter food revealed significant, positive relationships for yellowhammer (both projects) and up to five other species, depending on the control terms applied. Thus, positive effects of feeding on population change depend on the effective supply of seed to the species of interest. The hypothesis that winter food is currently limiting the populations concerned is also supported. 6. Synthesis and applications. Effective winter food provision to farmland bird populations has the potential to halt, and perhaps to reverse, declines in abundance. In practice, this means that agri-environment measures supplying significant quantities of winter food, such as stubbles preceded by low-input cereals, should succeed in changing population trends if they provide resources at the times of greatest need and if there is sufficient uptake.

Capsule Large buntings prefer cereal grains whilst sparrows also take oily seeds. Aims To determine seed food preferences of Tree Sparrow Passer montanus and Corn Bunting Emberiza calandra. Methods Forty seed choice experiments were conducted at two sites over two winters. In each experiment, two seed types were provided and the number of visits made by birds to each type was recorded over a set period. At one site, Tree Sparrows were colour-ringed, allowing choices made by individual birds to be recorded. Data were also collected for House Sparrow Passer domesticus, Yellowhammer Emberiza citrinella and Reed Bunting E. schoeniclus. Results All five species fed intensively on cereal grain, and wheat and oats were consistently preferred to barley. Sparrows and Reed Buntings also took maize, which was avoided by Corn Bunting and Yellowhammer. Tree Sparrow exhibited a broad diet, selecting cereal grain and oily seeds including sunflower and oilseed rape, but rye-grass seed was almost completely avoided. Concl...

Airborne LiDAR (Light Detection and Ranging) is a remote sensing technology that offers the ability to collect high horizontal sampling densities of high vertical resolution vegetation height data, over larger spatial extents than could be obtained by field survey. The influence of vegetation structure on the bird is a key mechanism underlying bird–habitat models. However, manual survey of vegetation structure becomes prohibitive in terms of time and cost if sampling needs to be of sufficient density to incorporate fine-grained heterogeneity at a landscape extent. We show that LiDAR data can help bridge the gap between grain and extent in organism–habitat models. Two examples are provided of bird–habitat models that use structural habitat information derived from airborne LiDAR data. First, it is shown that data on crop and field boundary height can be derived from LiDAR data, and so have the potential to predict the distribution of breeding Sky Larks in a farmed landscape. Secondly, LiDAR-retrieved canopy height and structural data are used to predict the breeding success of Great Tits and Blue Tits in broad-leaved woodland. LiDAR thus offers great potential for parameterizing predictive bird–habitat association models. This could be enhanced by the combination of LiDAR data with multispectral remote sensing data, which enables a wider range of habitat information to be derived, including both structural and compositional characteristics.

Tree Sparrows Passer montanus showed a strong preference for nest-sites adjacent to wetland habitats, and avoidance of sites on intensively managed mixed farmland distant from Rutland Water. A variety of wetland edge habitats were frequently used by foraging adult birds when provisioning nestlings, and invertebrate prey of aquatic origin was frequently recorded in chick diet. We suggest that the wetland edge habitats at the study sites played a key role in providing adequate diversity and availability of suitable invertebrate prey to allow successful chick rearing throughout the long breeding season of this multi-brooded passerine. It is possible that large areas of formerly occupied farmland in the UK no longer provide these invertebrate resources due to the effects of intensification in the late 20th century. There was no evidence that the availability of supplementary seed food within 1 km of the nest-site influenced nest-site choice, or affected productivity. It is probable that the importance of seed food resources to the persistence of Tree Sparrow populations operates on a larger spatial scale than that tested in this study, due to the greater mobility of Tree Sparrows in the non-breeding season, when seed resources are most likely to be a key limiting factor. When considering conservation management aimed at recovering breeding populations of Tree Sparrows, the key resources of seed food, invertebrate food and nest-sites must be made available at appropriate spatial scales.

This work was undertaken to devise a technique to measure the height of crops in farmland fields through remote sensing. Crop height is a useful spatial variable which, when measured by ground-based manual survey, has proven to be an important predictor of bird species population. An airborne scanning laser system capable of measuring topography to a height accuracy of better than 10 cm was used to acquire height data over a region of farmland near Oxford, UK. A scanning laser was pulsed from an aircraft at the ground, measuring the time between transmission and receipt of the last significant return signal. Differential Geographical Positioning System (GPS) and onboard attitude sensors were combined with these delay times to construct a set of spot heights through the region. Crop height was also measured from the ground. Pulses were returned from mainly within the crop, rather than predominantly the canopy or ground, so an algorithm to measure the variation of the returned height, after detrending the h...

SummaryOrnithological surveys were carried out in the remnant forests of the island of Negros, in the central Philippines, over five weeks in the summer of 1991. From this work it is concluded that, without the implementation of immediate conservation measures, the global extinction of four bird species is likely to occur in the near future. These are Negros Fruit-dovePtilinopus arcanus, Negros Bleeding-heartGallicolumba keayi, Writhed-billed HornbillAceros waldeniand White-throated Jungle-flycatcherKhinomyias albi-gularis. Another four species restricted to the lowlands of Negros and the adjacent island of Panay, Visayan Tarictic HornbillPenelopides panini, White-winged Cuckoo-shrikeCora-cina ostenta, Flame-templed BabblerStachyris speciosaand Visayan FlowerpeckerDicaeum (australe) haematostictum, must be considered under extreme threat, and the endemic Negros Striped-babblerStachyris nigrorumis under considerable pressure. A further twelve species listed as globally threatened are also in serious danger of extinction on Negros. This paper details the results of fieldwork and presents our conclusions and suggestions for conservation, which must include the direct preservation of the last fragments of lowland forest on the island.

Agricultural intensification is blamed for the plummeting populations of these birds. House-sparrow populations have declined sharply in Western Europe in recent decades1,2, but the reasons for this decline have yet to be identified, despite intense public interest in the matter. Here we use a combination of field experimentation, genetic analysis and demographic data to show that a reduction in winter food supply caused by agricultural intensification is probably the principal explanation for the widespread local extinctions of rural house-sparrow populations in southern England. We show that farmland populations exhibit fine-level genetic structuring and that some populations are unable to sustain themselves (sinks), whereas others act as sources.