Showing papers by "Royal Society for the Protection of Birds published in 2007"

Climate envelope, life history traits and the resilience of birds facing global change

Abstract: Few studies have examined how life history traits and the climate envelope influence the ability of species to respond to climate change and habitat degradation. In this study, we test whether 18 species-specific variables, related to the climate envelope, ecological envelope and life history, could predict recent population trends (over 17 years) of 71 common breeding bird species in France. Habitat specialists were declining at a much higher rate than generalists, a sign that habitat quality is decreasing globally. The lower the thermal maximum (temperature at the hot edge of the climate envelope), the more negative are the population trends and the less tolerant these species are climate warming, regardless of the thermal range over which these species occur. The life history trait ‘the number of broods per year’ was positively related to recent trends, suggesting that single-brooded species might be more sensitive to advances in food peak due to climate change, as it increases the risk of mistiming their single-breeding event. Annual fecundity explained long-term declines, as it is a good proxy for most other demographic rates, with shorter-lived species being more sensitive to global change: individuals of species with higher fecundity might have too short a life to learn to adapt to directional changes in their environment. Finally, there was evidence that natal dispersal was a predictor of recent trends, with species with high natal dispersal experiencing smaller population declines than species with low natal dispersal. This is expected if the higher the natal dispersal, the larger the ability to shift spatially when facing changes in local habitat or climate, in order to track optimal conditions and adapt to global change. Identifying decline-promoting factors allow us to infer mechanisms responsible for observed declines in wild bird populations facing global change, and by doing so allow for a more pre-emptive approach to conservation planning.

Improvements to the Red List Index.

Abstract: The Red List Index uses information from the IUCN Red List to track trends in the projected overall extinction risk of sets of species. It has been widely recognised as an important component of the suite of indicators needed to measure progress towards the international target of significantly reducing the rate of biodiversity loss by 2010. However, further application of the RLI (to non-avian taxa in particular) has revealed some shortcomings in the original formula and approach: It performs inappropriately when a value of zero is reached; RLI values are affected by the frequency of assessments; and newly evaluated species may introduce bias. Here we propose a revision to the formula, and recommend how it should be applied in order to overcome these shortcomings. Two additional advantages of the revisions are that assessment errors are not propagated through time, and the overall level extinction risk can be determined as well as trends in this over time.

International Conservation Policy Delivers Benefits for Birds in Europe

Abstract: Conservation of the planet's biodiversity will depend on international policy intervention, yet evidence-based assessment of the success of such intervention is lacking. Poor understanding of the effectiveness of international policy instruments exposes them to criticism or abandonment and reduces opportunities to improve them. Comparative analyses of population trends provide strong evidence for a positive impact of one such instrument, the European Union's Birds Directive, and we identify positive associations between the rate of provision of certain conservation measures through the directive and the response of bird populations. The results suggest that supranational conservation policy can bring measurable conservation benefits, although future assessments will require the setting of quantitative objectives and an increase in the availability of data from monitoring schemes.

Population trends of widespread woodland birds in Europe

Abstract: We explore population trends of widespread and common woodland birds using data from an extensive European network of ornithologists for the period 1980–2003. We show considerable differences exist in the European trends of species according to the broad habitat they occupy and the degree to which they specialize in habitat use. On average, common forest birds are in shallow decline at a European scale; common forest birds declined by 13%, and common forest specialists by 18%, from 1980 to 2003. In comparison, populations of common specialists of farmland have declined moderately, falling on average by 28% from 1980 to 2003. These patterns contrast with that shown by generalist species whose populations have been roughly stable over the same period, their overall index increasing by 3%. There was some evidence of regional variation in the population trends of these common forest species. The most obvious pattern was the greater stability of population trends in Eastern Europe compared with other regions considered. Among common forest birds, long-distance migrants and residents have on average declined most strongly, whereas short-distance migrants have been largely stable, or have increased. There was some evidence to suggest that ground- or low-nesting species have declined more strongly on average, as have forest birds with invertebrate diets. Formal analysis of the species trends confirmed the influence of habitat use, habitat specialization and nest-site; the effects of region and migration strategy were less clear-cut. There was also evidence to show that year-to-year variation in individual species trends at a European scale was influenced by cold winter weather in a small number of species. We recommend that the species trend information provided by the new pan-European scheme should be used alongside existing mechanisms to review the conservation status of European birds. The analysis also allows us to reappraise the role of common forest bird populations as a potential barometer of wider forest health. The new indicator appears to be a useful indicator of the state of widespread European forest birds and might prove to be a useful surrogate for trends in forest biodiversity and forest health, but more work is likely to be needed to understand the interaction between bird populations and their drivers in forest.

Should conservation strategies consider spatial generality? Farmland birds show regional not national patterns of habitat association.

Abstract: A key assumption underlying any management practice implemented to aid wildlife conservation is that it will have similar effects on target species across the range it is applied. However, this basic assumption is rarely tested. We show that predictors [nearly all associated with agri-environment scheme (AES) options known to affect European birds] had similar effects for 11 bird species on sites with differing farming practice (pastoral vs. mixed farming) or which differed in the density at which the species was found. However, predictors from sites in one geographical region tended to have different effects in other areas suggesting that AES options targeted at a regional scale are more likely to yield beneficial results for farmland birds than options applied uniformly in national schemes. Our study has broad implications for designing conservation strategies at an appropriate scale, which we discuss.

National Threatened Species Listing Based on IUCN Criteria and Regional Guidelines: Current Status and Future Perspectives

Abstract: As countries worldwide become increasingly interested in conserving biodiversity, the profile of national threatened species lists expands and these lists become more influential in determining conserva- tion priorities. The World Conservation Union (IUCN) Categories and Criteria for evaluating extinction risk, originally intended for use at the global level, are increasingly being used at the national level. To facilitate this process, the IUCN recently published guidelines for the application of the criteria at subglobal levels. We evaluated the application of these guidelines, focusing on the opinions and experience of the global community of national assessors. To assess the extent to which IUCN criteria have been used in official national listing efforts, we sent a survey to 180 Convention on Biological Diversity national focal points designated by gov- ernments. Of the respondents, 77% had developed national threatened species lists. Of these, 78% applied a version of the IUCN criteria, and 88% plan to produce future threatened species lists. The majority of this last group (83%) will use IUCN criteria. Of the countries that have or will develop a threatened species list, 82% incorporated their list or the IUCN criteria into national conservation strategies. We further explored the issues highlighted by the survey results by integrating the experience of assessors that have produced national lists. Most of the problems national assessors faced when applying the IUCN criteria arose when the criteria were applied at the regional level without the IUCN Regional Guidelines and when assessors were confused about the purpose of the IUCN criteria and lacked training in their proper use. To improve their clarity and increase their repeatability, we recommend that the IUCN increase communication and information exchange among countries and between regional and global assessors, potentially through an interactive Web site, to facilitate the development of national red lists and to improve their conservation value within and between countries.

Future novel threats and opportunities facing UK biodiversity identified by horizon scanning

Abstract: 1. Horizon scanning is an essential tool for environmental scientists if they are to contribute to the evidence base for Government, its agencies and other decision makers to devise and implement environmental policies. The implication of not foreseeing issues that are foreseeable is illustrated by the contentious responses to genetically modified herbicide-tolerant crops in the UK, and by challenges surrounding biofuels, foot and mouth disease, avian influenza and climate change. 2. A total of 35 representatives from organizations involved in environmental policy, academia, scientific journalism and horizon scanning were asked to use wide consultation to identify the future novel or step changes in threats to, and opportunities for, biodiversity that might arise in the UK up to 2050, but that had not been important in the recent past. At least 452 people were consulted. 3. Cases for 195 submitted issues were distributed to all participants for comments and additions. All issues were scored (probability, hazard, novelty and overall score) prior to a 2-day workshop. Shortlisting to 41 issues and then the final 25 issues, together with refinement of these issues, took place at the workshop during another two rounds of discussion and scoring. 4. We provide summaries of the 25 shortlisted issues and outline the research needs. 5. We suggest that horizon scanning incorporating wide consultation with providers and users of environmental science is used by environmental policy makers and researchers. This can be used to identify gaps in knowledge and policy, and to identify future key issues for biodiversity, including those arising from outside the domains of ecology and biodiversity. 6. Synthesis and applications. Horizon scanning can be used by environmental policy makers and researchers to identify gaps in knowledge and policy. Drawing on the experience, expertise and research of policy advisors, academics and journalists, this exercise helps set the agenda for policy, practice and research.

NSAIDs and scavenging birds: potential impacts beyond Asia's critically endangered vultures

Abstract: Veterinary treatment of livestock with diclofenac, a non-steroidal anti-inflammatory drug (NSAID), has caused catastrophic declines of Gyps vultures in Asia. This has highlighted a lack of knowledge on the potential impacts of NSAIDs on scavenging birds. Surveys of veterinarians and zoos document the outcomes of the treatment of over 870 scavenging birds from 79 species. As well as diclofenac, carprofen and flunixin were associated with mortality, with deaths observed in 13 and 30% of cases, respectively. Mortality was also found following treatment with ibuprofen and phenylbutazone. NSAID toxicity was reported for raptors, storks, cranes and owls, suggesting that the potential conservation impact of NSAIDs may extend beyond Gyps vultures and could be significant for New World vultures. In contrast, there were no reported mortalities for the NSAID meloxicam, which was administered to over 700 birds from 60 species. The relative safety of meloxicam supports other studies indicating the suitability of this NSAID to replace diclofenac in Asia.

The impact of predator control on lapwing Vanellus vanellus breeding success on wet grassland nature reserves

Abstract: Summary 1Whilst the widespread declines in breeding grassland waders in many parts of Europe have been associated with changes in agriculture, there is concern that predation may compromise recovery of wader populations, even in situations where habitat is suitable, such as nature reserves managed for breeding waders. 2An 8-year cross-over experiment was used to examine the effect of red fox Vulpes vulpes and carrion crow Corvus corone control on breeding performance and population trends of lapwing Vanellus vanellus on 11 lowland wet grasslands. 3Predator densities in the absence of control measures were highly variable among sites, and consequently the numbers of predators removed were similarly variable. Overall, predator control measures resulted in a 40% decline in adult fox numbers and a 56% reduction in territorial crows. 4There was no overall effect of predator control on the failure rate of 3139 lapwing nests. However, the effect of predator control varied significantly among sites, reflecting the variation in predator densities. Predator control measures were more likely to result in increased nest survival at sites where predator densities were high. 5Nest-temperature loggers deployed at seven sites indicated that 88% of nest predations occurred during darkness, suggesting nocturnal mammalian predators. 6At seven sites predator control had no overall effect on chick survival, monitored by radio-tracking 459 chicks, but there were differences in the effect of predator control among sites. Densities of predators were low during years without predator control measures at the majority of these sites. 7At six further sites breeding success, assessed from the proportion of adults accompanied by young late in the season, was twice as high in years when predators were controlled. 8There was no overall effect of predator control on lapwing population trends across the experimental sites. 9Synthesis and applications. This study highlights the need for information on predator densities and the impact of predators on nest and chick survival, before embarking on predator control measures at a particular site. A decision tree for determining the circumstances in which fox and/or crow control may be both necessary and effective is recommended.

Intake rates and the functional response in shorebirds (Charadriiformes) eating macro-invertebrates

Abstract: As field determinations take much effort, it would be useful to be able to predict easily the coefficients describing the functional response of free-living predators, the function relating food intake rate to the abundance of food organisms in the environment. As a means easily to parameterise an individual-based model of shorebird Charadriiformes populations, we attempted this for shorebirds eating macro-invertebrates. Intake rate is measured as the ash-free dry mass (AFDM) per second of active foraging; i.e. excluding time spent on digestive pauses and other activities, such as preening. The present and previous studies show that the general shape of the functional response in shorebirds eating approximately the same size of prey across the full range of prey density is a decelerating rise to a plateau, thus approximating the Holling type 11 ('disc equation') formulation. But field studies confirmed that the asymptote was not set by handling time, as assumed by the disc equation, because only about half the foraging time was spent in successfully or unsuccessfully attacking and handling prey, the rest being devoted to searching. A review of 30 functional responses showed that intake rate in free-living shorebirds varied independently of prey density over a wide range, with the asymptote being reached at very low prey densities (< 150/m(-2)). Accordingly, most of the many studies of shorebird intake rate have probably been conducted at or near the asymptote of the functional response, suggesting that equations that predict intake rate should also predict the asymptote. A multivariate analysis of 468 'spot' estimates of intake rates from 26 shorebirds identified ten variables, representing prey and shorebird characteristics, that accounted for 81 % of the variance in logarithm-transformed intake rate. But four-variables accounted for almost as much (77.3 %), these being bird size, prey size, whether the bird was an oystercatcher Haematopus ostralegus eating mussels Mytilus edulis, or breeding. The four variable equation under-predicted, on average, the observed 30 estimates of the asymptote by 11.6%, but this discrepancy was reduced to 0.2% when two suspect estimates from one early study in the 1960s were removed. The equation therefore predicted the observed asymptote very successfully in 93 % of cases. We conclude that the asymptote can be reliably predicted from just four easily measured variables. Indeed, if the birds are not breeding and are not oystercatchers eating mussels, reliable predictions can be obtained using just two variables, bird and prey sizes. A multivariate analysis of 23 estimates of the half-asymptote constant suggested they were smaller when prey were small but greater when the birds were large, especially in oystercatchers. The resulting equation could be used to predict the half-asymptote constant, but its predictive power has yet to be tested. As well as predicting the asymptote of the functional response, the equations will enable research workers engaged in many areas of shorebird ecology and behaviour to estimate intake rate without the need for conventional time-consuming field studies, including species for which it has not yet proved possible to measure intake rate in the field.

Safety of meloxicam to critically endangered Gyps vultures and other scavenging birds in India

Abstract: Widespread veterinary use of the non-steroidal anti-inflammatory drug diclofenac is responsible for the population collapse of three species of Gyps vulture in south Asia; these species are now critically endangered. Vultures die when they consume carcasses of livestock that contain lethal residues of diclofenac. National and international conservation organizations have urgently recommended that diclofenac be banned and replaced with alternative drugs that are relatively safe to Gyps vultures and other scavenging birds. We tested the safety of the NSAID meloxicam on the oriental white-backed vulture, long-billed vulture and a range of other scavenging birds in India (Egyptian vulture Neophron percnopterus, cattle egret Bubulcus ibis, house crow Corvus splendens, large-billed crow Corvus machrorhynchos and common mynah Acridotheres tristis). Meloxicam was administered by oral intubation [at 0.5 and 2.0 mg kg−1 vulture body weight (bw)], or through feeding with muscle or liver tissue (at 0.3 to 2.1 mg kg−1 vulture bw) from meloxicam-treated buffalo Bubalus bubalis. We estimate that 2.0 mg kg−1 bw is the maximum likely exposure in the wild. All 31 Gyps vultures and the 20 other scavenging birds given meloxicam survived. Feeding behaviour remained normal and there were no significant differences between the treated and control groups in body mass, or the blood haematology and biochemistry parameters monitored, including those known to be affected by diclofenac (uric acid levels and alanine transferase activity). Meloxicam is used to treat a wide range of livestock ailments and is licensed and manufactured in India. We recommend that meloxicam be introduced as rapidly as possible across the Indian sub-continent as an alternative to diclofenac.

The effect of supplementary winter seed food on breeding populations of farmland birds: evidence from two large‐scale experiments

Abstract: 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.

Remote monitoring of nests using digital camera technology

Abstract: Although cameras have been used for many years to collect data at birds' nests, recent advances in digital technology have led to increased storage capacity, faster and easier review of data, and reduced power consumption. The development of sophisticated triggering mechanisms, such as video motion detection, herald a new era of portable, energy-efficient systems that require less frequent maintenance. We used a digital infrared camera system to monitor predation events at the nests of ground-nesting Lapwings (Vanellus vanellus; N= 40) and tree-nesting Spotted Flycatchers (Muscicapa striata; N= 17). Eight predator species were recorded taking eggs or chicks at Lapwing (N= 10) and Spotted Flycatcher (N= 7) nests, including red fox (Vulpes vulpes), badger (Meles meles), sheep (Ovis aries), and Carrion Crow (Corvus corone) at Lapwing nests and Eurasian Jay (Garrulus glandarius), European Buzzard (Buteo buteo), Great-spotted Woodpecker (Dendrocopus major), and domestic cat (Felis catus) at flycatcher nests. We tested three system configurations in an attempt to minimize power requirements and maximize predation-event recording capability. We found that the use of a passive-infrared sensor to awaken the system from standby mode did not compromise reliability and reduced power consumption. With this system, a 38-A h battery operated the system for 120 h with no maintenance at a cost per unit of about $800 (US; or £400 UK Sterling). Further modifications would permit adaptation of the system for a wide range of scientific and nest surveillance operations.

Rate of decline of the Oriental white-backed vulture population in India estimated from a survey of diclofenac residues in carcasses of ungulates

Abstract: The non-steroidal anti-inflammatory drug diclofenac is a major cause of the rapid declines in the Indian subcontinent of three species of vultures endemic to South Asia. The drug causes kidney failure and death in vultures. Exposure probably arises through vultures feeding on carcasses of domesticated ungulates treated with the drug. However, before the study reported here, it had not been established from field surveys of ungulate carcasses that a sufficient proportion was contaminated to cause the observed declines. We surveyed diclofenac concentrations in samples of liver from carcasses of domesticated ungulates in India in 2004–2005. We estimated the concentration of diclofenac in tissues available to vultures, relative to that in liver, and the proportion of vultures killed after feeding on a carcass with a known level of contamination. We assessed the impact of this mortality on vulture population trend with a population model. We expected levels of diclofenac found in ungulate carcasses in 2004–2005 to cause oriental white-backed vulture population declines of 80–99% per year, depending upon the assumptions used in the model. This compares with an observed rate of decline, from road transect counts, of 48% per year in 2000–2003. The precision of the estimate based upon carcass surveys is low and the two types of estimate were not significantly different. Our analyses indicate that the level of diclofenac contamination found in carcasses of domesticated ungulates in 2004–2005 was sufficient to account for the observed rapid decline of the oriental white-backed vulture in India. The methods we describe could be used again to assess changes in the effect on vulture population trend of diclofenac and similar drugs. In this way, the effectiveness of the recent ban in India on the manufacture and importation of diclofenac for veterinary use could be monitored.

Restoration of wet features for breeding waders on lowland grassland

Abstract: Summary 1. Over the last century, the loss of around half of the world’s wetlands, principally through drainage and conversion to agriculture, has been one of the main drivers of declines in breeding waders. Across Europe, nature reserves have been effective conservation islands for breeding waders, but management of the wider countryside is needed for more wide-scale population recovery. This is likely to require the restoration of wet features, but in a manner which is compatible with farming operations. 2. Here we explore the extent to which three types of wet feature influence the distribution of breeding lapwings Vanellus vanellus and their chicks on grassland. Footdrains are shallow channels used historically for drainage, but which can also be created and managed for water retention and cause little disruption to farming activities. Footdrain floods are areas where water overtops footdrains. Isolated pools are unmanaged areas of surface water resulting from rainfall or high water tables. 3. We selected 70 fields on nine sites which spanned the range of wet feature type and cover in early April. By May, only around 10% of the water within isolated pools remained, whereas 30‐40% water was maintained in footdrains into June. 4. Fields with high footdrain flood densities attracted significantly higher densities of nesting lapwing and nests were more likely to be within 50 m of footdrain floods. Later in the season, footdrains were the primary remaining water source, and chick field use increased significantly with footdrain density. Chicks were also more likely to forage nearer footdrain floods in areas of wet mud created by receding water levels. 5. Synthesis and applications. Areas of shallow, small-scale flooding are of critical importance for breeding waders. Management tools such as footdrains, coupled with appropriate hydrological management, provide a means of retaining water throughout the breeding season. Installation of these features is relatively simple, but maintaining sufficient water levels within the system is critical, especially in the face of increasingly unpredictable water supplies associated with climate change. Such management tools offer a solution that may be both effective at improving breeding wader populations and practicable for commercial grazing marsh management.

Habitat change and woodland birds in Britain: implications for management and future research: Habitat change and woodland birds

Abstract: There is increasing evidence that changes in habitat structure in the form of reduced understorey and loss of open habitats, both probably a result of increases in shading and deer browsing, may be responsible for causing recent changes in the composition of breeding bird communities in many lowland British woods and forests. In contrast, management of upland coniferous forests may prevent the attainment of mature and old-growth structures which would benefit community development in these new ecosystems. We suggest that the key challenge for woodland conservation policy is to create larger areas of both young-growth and old-growth habitat. These objectives need not necessarily conflict with each other, or with other multipurpose forestry objectives, provided that they inform strategic plans and are targeted at appropriate locations and scales. In the lowlands, the current large stock of middle-aged, often unmanaged and species-poor woodland provides an opportunity to restore or create new woodland habitats of high biodiversity value. The development of woodfuel markets may effectively increase the amount of young-growth but it is unclear exactly what habitat structures might be created. In the uplands, allowing more natural development of native woodland in mosaics with other habitats may provide opportunities for both old- and young-growth species. For the foreseeable future, deer impacts will continue to be widespread and probably increasingly severe in many areas. In view of the uncertainty about the implications of climate change for woodland ecosystems, a strong case can be made for attempting to buffer valued wildlife communities against damaging effects by creating and maintaining high structural diversity at a range of scales and increasing the area of woodland.

Recent changes in bird populations in British broadleaved woodland

Abstract: This paper presents estimated national and regional changes in numbers of breeding woodland birds in predominantly broadleaved woodland in Britain between the mid 1980s and 2003–04, derived from the Repeat Woodland Bird Survey (RWBS). A total of 405 sites across Britain for which historical data on bird populations were available were re-surveyed by BTO and RSPB fieldworkers during the RWBS. Changes were estimated separately for sites surveyed by the RSPB (n = 252) and BTO (n = 153) because of differences between the two groups in the field methods used in the original surveys. Changes between the 1960s and 1970s and 2003–04 were also estimated with the BTO data set only. The BTO and RSPB sites provide geographically complementary coverage of Britain and together provide much more widespread coverage than did the Common Bird Census (CBC), the former national monitoring scheme. Nationally, between the 1980s and 2003–04, six species declined significantly and three increased significantly based on the RSPB data, whereas eight declined and 13 increased according to the BTO data, with good correspondence between the changes recorded by the two data sets (only seven of 34 species showing trends differing in direction). Eight species showed large national declines (> 25%) according to both data sets: Garden Warbler Sylvia borin, Lesser Redpoll Carduelis cabaret, Lesser Spotted Woodpecker Dendrocopos minor, Spotted Flycatcher Muscicapa striata, Tree Pipit Anthus trivialis, Willow Tit Poecile montanus, Willow Warbler Phylloscopus trochilus and Wood Warbler P. sibilatrix. Eleven species showed large national increases (> 25%) in both data sets: Blackcap Sylvia atricapilla, Blue Tit Cyanistes caeruleus, Common Chiffchaff Phylloscopus collybita, Coal Tit Periparus ater, Great Spotted Woodpecker Dendrocopos major, Great Tit Parus major, Green Woodpecker Picus viridis, Goldcrest Regulus regulus, European Robin Erithacus rubecula, Eurasian Treecreeper Certhia familaris and Winter Wren Troglodytes troglodytes. Analysis of the longer-term changes using the BTO data set showed significant declines between the 1960s and 2003–04 in seven species and increases in 12 species. The large declines detected by the national monitoring schemes (CBC/BBS) for Lesser Spotted Woodpecker, Lesser Redpoll, Spotted Flycatcher, Tree Pipit, Willow Tit, Willow Warbler and Wood Warbler were all confirmed by the RWBS but the declines of the Common Bullfinch Pyrrhula pyrrhula, Marsh Tit Poecile palustris and Mistle Thrush Turdus viscivorus were not clearly supported. The declines detected by the RWBS for Garden Warbler, Pied Flycatcher Ficedula hypoleuca and Common Redstart Phoenicurus phoenicurus were not evident from the national monitoring schemes. Most of the increases detected by the monitoring schemes were confirmed by the RWBS. However, the large increases detected by the RWBS for Coal Tit, Goldcrest, Great Tit and Eurasian Treecreeper were unexpected. All long-distance migrants have declined whilst medium-distance migrants (Blackcap and Common Chiffchaff) have increased. Also, rare and specialist woodland species have fared less well than common and generalist species.

What effects do walkers and dogs have on the distribution and productivity of breeding European Nightjar Caprimulgus europaeus

Abstract: Several successive studies of European Nightjars Caprimulgus europaeus (hereafter, Nightjar) on the Dorset heaths demonstrated negative effects of the proximity of urban development and associated disturbance from access on foot by people and dogs. Surrogate measures of human density and settlement, including the amount of developed land around each heathland patch and the number of houses, were significantly and negatively related to the density of Nightjars (using data from the 1992 national survey) on heathland patches, regardless of patch size. These findings prompted targeted field studies, the subject of this paper, which investigated the mechanisms and effects of recreational disturbance on breeding Nightjars. Fieldwork in 2002 focused on a suite of heathland sites representing a range of access from sites closed to the public to heaths heavily used for recreation, notably by dog walkers. Studies in 2003 concentrated on the heavily used heaths. Nests which failed were significantly closer to paths, tended to be closer to the main points of access to heaths, in areas with higher footpath density, notably of high levels of use, and in more sparsely vegetated locations. The proximate cause of nest failure was most frequently egg predation. Nest cameras, deployed in 2003 in an attempt to identify the predators of eggs or chicks, recorded just one instance of predation, that of an egg by a Carrion Crow Corvus corone , and two instances of the incubating bird being flushed by a dog, once from an egg and once from a chick, neither event preventing fledging. Flushing rate of Nightjars from the nest was associated with the height of vegetation around the nest and the extent of nest cover. The studies indicate that access disturbance interacts with environmental conditions for breeding birds. Birds flush more readily from eggs, which are highly visible when exposed, especially in areas with sparse nest cover, leaving them vulnerable to predation. Although Nightjar flushing rates were observed to be low in 2003, just one event leading to predation is enough to end that nesting attempt. Management measures are recommended to minimize the effects of walkers and their dogs on Nightjars.

Prioritizing the world's islands for vertebrate-eradication programmes

Abstract: In the last 400 years, more species have become extinct on small islands than on continents. Yet, scant attention has hitherto been paid to prioritizing island restorations. Nevertheless, considerable conservation effort is now devoted to removing a major cause of these extinctions – invasive alien vertebrates. Because modern techniques allow the clearance of invasive vertebrates from quite large islands (up to 1000 km2), many islands are candidates for restoration. A robust strategy for allocating available funds is urgently needed. It requires, for each candidate island, an objective estimation of conservation gain and a method for predicting its financial cost. Our earlier work showed that a good first-pass estimate of vertebrate eradication costs can be made using just island area and target species. Costs increase with island area, while rodents are more expensive per unit area than ungulates. Here, we develop a method for assessing the conservation benefit of a proposed eradication and apply the method to threatened birds, but not other taxa. The method, combining information on how threatened a species is, on the impact of alien vertebrates on that species and on the islands on which the species occurs, allows us to present a means of determining which islands yield the greatest conservation benefit per unit of expenditure on vertebrate eradication. In general, although greater overall benefit would accrue to birds from eradication of invasive vertebrates on larger islands, benefit per unit of expenditure is the highest on relatively small islands, and we identify those that should be priority targets for future eradications. Crucially, this quantitative assessment provides considerable efficiency gains over more opportunistic targeting of islands. The method could be adapted to prioritize islands on a regional or national basis, or with different conservation gains in mind.

Effects of Volcanic Ash on the Forest Canopy Insects of Montserrat, West Indies

Abstract: The impact of ash deposition levels on canopy arthropods was studied on the West Indian island of Montserrat, the site of an ongoing volcanic eruption since 1995. Many of the island's natural habitats have been buried by volcanic debris, and remaining forests regularly receive volcanic ash deposition. To test the effect of ash on canopy arthropods, four study sites were sampled over a 15-mo period. Arthropod samples were obtained using canopy fogging, and ash samples were taken from leaf surfaces. Volcanic ash has had a significant negative impact on canopy arthropod populations, but the decline is not shared equally by all taxa present, and total population variation is within the variance attributed to other aboitic and biotic factors. The affected populations do not differ greatly from those of the neighboring island of St. Kitts, which has not been subject to recent volcanic activity. This indicates that observed effects on Montserrat's arthropod fauna have a short-term acute response to recent ash deposition rather than a chronic depression caused by repeated exposure to ash over the last decade.

Stand management: a threat or opportunity for birds in British woodland?: Stand management and birds in British woodland

Abstract: Recent studies have suggested that the neglect of stand management is having a detrimental effect on the habitat of a number of woodland birds in Britain. The remedy, to reinstate active management, appears to run counter to a number of other conservation recommendations such as re-wilding and naturalizing of stands. We attempt to unpick this apparent conflict by considering the resource needs of British woodland birds relative to those of birds elsewhere in Europe, and whether these needs differ between those with declining and those with increasing populations. We also consider how these requirements relate to stand management and stand dynamics and consider options for future management. We found that whilst stand stage per se did not discriminate between the declining and increasing species pools, correspondence analysis suggested that there were differences between the groups in their preferred habitat features. Declining woodland birds in Britain appear to be most closely associated with the presence of deciduous trees in the stand, an open canopy, and ecotonal structures. Species present in the near continent, but not in Britain, were associated with deciduous snags, large trees, canopy layer and holes. Species increasing in Britain were located between these groups on an axis of woodland maturity, and most strongly associated with habitat features of canopy layer and holes. Stand management can help provide the structures apparently preferred by many of the declining species and, if targeted, can deliver them at a more rapid rate than development of similar features through natural stand dynamics. However, there are often multiple pathways to particular structures and a single recommendation of active management is likely to be insufficient to secure the necessary features in most situations. In addition, habitat features important in Europe as a whole may not be the most critical at a local or regional scale. The varying requirements of the different species pools suggest that greater recognition of this would be appropriate in developing conservation strategies in different regions, and greater clarity is desirable over conservation objectives and habitat structures for particular woodlands.

Impacts of a volcanic eruption on the forest bird community of Montserrat, Lesser Antilles

Abstract: Volcanic eruptions are an important and natural source of catastrophic disturbance to ecological communities. However, opportunities to study them are relatively rare. Here we report on the effects of the eruption of the Soufriere Hills volcano on the forest bird community of the Lesser Antillean island of Montserrat. The island's species-poor avifauna includes 11 restricted-range species, including the Critically Endangered endemic Montserrat Oriole Icterus oberi. Analysis of monitoring data from 1997 to 2005 indicates that counts of most species were substantially lower following major ashfalls. However, this effect was short-lived, with rapid population recovery in subsequent years. Furthermore, levels of seasonal rainfall appear to have been at least as important in determining population trends as ashfall. Overall, most species were at least as abundant at the end of the study as at the start, and no forest bird species have been extirpated from Montserrat. We discuss potential ecological drivers of ashfall impacts on populations: there is some evidence that terrestrial foragers were most severely affected.

Testing the effects of recreational disturbance on two upland breeding waders

Abstract: Previous work has shown that Golden Plovers Pluvialis apricaria guarding chicks utilize heavily disturbed habitat at a lower rate than surrounding areas, but that such rates of avoidance are reduced when the movement of people is restricted to a surfaced footpath. However, there remained some unanswered questions, which are addressed in this paper. First, we examine to what extent habitat avoidance is dependent upon visitor numbers, and find no evidence that Golden Plovers avoided disturbed areas at a site where visitor pressure was half that previously studied. Secondly, we examine whether these relationships between habitat occupancy and disturbance apply to other upland waders and find that Dunlin Calidris alpina habitat utilization in disturbed areas showed a non-significant increase of approximately 50% following the provision of a surfaced footpath, in a manner similar to that observed for Golden Plover. Thirdly, we examine whether the large numbers of visitors (120 per weekend day) using the surfaced footpath impact on Golden Plover breeding success, despite the lack of habitat avoidance. There was no evidence that nest location, clutch survival or chick growth rates were reduced close to the footpath. Together, these results suggest that high levels of disturbance can impact upon habitat usage by upland waders, but only in limited circumstances where visitor pressure is very high (greater than at least 30 visitors per weekend day). However, access to such areas can be permitted for large numbers of visitors without impacting upon wader reproductive performance through the provision of a well-surfaced route.

Modelling the winter distribution of a rare and endangered migrant, the Aquatic Warbler Acrocephalus paludicola

Abstract: The Aquatic Warbler Acrocephalus paludicola is one of the most threatened Western Palearctic passerine species, classified as globally Vulnerable. With its breeding grounds relatively secure, a clear need remains for the monitoring and protection of the migration and wintering grounds of this rare and endangered migrant. Recent research has shown that the Aquatic Warbler migrates through northwest Africa in autumn and spring. The wintering grounds are apparently limited to wetlands of sub-Saharan West Africa, with records from only about 20 localities in Mauritania, Mali, Senegal and Ghana. Given the lack of knowledge of its whereabouts, we decided to use the available data to predict the wintering distribution of the Aquatic Warbler with the help of Geographic Information Systems (GIS). We used a novel approach to model the distribution of rarely recorded species, which is based on a combination of presence-only and presence‐absence modelling techniques. Using the program BIOMOD, we thus generated four progressively more conservative predictions of where the Aquatic Warbler overwinters in Africa. Whereas the most permissive model predicts the Aquatic Warbler to be found in a latitudinal band stretching from the Senegal river delta all the way to the Red Sea coast, the most restrictive model suggests a much smaller area concentrated within the regions around the Senegal river delta in northern Senegal and southern Mauritania and around the Niger inundation zone in southern Mali and eastern Burkina Faso. Such model predictions may be useful guidelines to focus further field research on the Aquatic Warbler. Given the excellent model predictions in this study, this novel technique may prove useful to model the distribution of other rare and endangered species, thus providing a means to guide future survey efforts.

Habitat selection and foraging behaviour of breeding Eurasian Woodcock Scolopax rusticola : a comparison between contrasting landscapes

Abstract: Diet, feeding behaviour and habitat selection of breeding Eurasian Woodcock Scolopax rusticola were studied by radiotracking birds from March to July in two contrasting situations: a 171-ha lowland plantation of Sycamore Acer pseudoplatanus, Beech Fagus sylvaticus and pine Pinus sylvestris/P. nigra in Derbyshire, central England, and an area of c. 900 ha of fragmented, naturally regenerating birch Betula pendula/B. pubescens woodland and hill margin in an upland glen in Angus, northeast Scotland. Earthworms were the most important diet component of adults and chicks in terms of biomass at both sites (50–80%), the rest comprising mainly spiders, harvestmen and beetles. In spring both sexes flew c. 1 km after dusk to feed on fields at night, with up to 94% of nocturnal radiolocations on fields in March, dropping to 18% in July. This behaviour probably reflected seasonal changes in the relative availability of earthworms in fields and woodland. Diurnal home range sizes were similar at both sites and the mean size of 30-day ranges was 62 ± 20 ha (± se), although Woodcock changed locations regularly and areas used for feeding on a daily basis were typically smaller than 1 ha. In the lowland plantation, Sycamore with Dog's Mercury Mercurialis perennis ground cover was highly used relative to availability. In the upland margin study area, the same held for dense sapling-stage birch. These habitats appear to represent a compromise between food availability and protection from avian predators. Recently documented changes in the structure of British woods during the last 30 years, suggestive of reduced management and increased grazing/browsing, are likely to have been detrimental to breeding Woodcock.

Habitat type determines the effects of disturbance on the breeding productivity of the Dartford Warbler Sylvia undata

Abstract: Numerous studies have examined the causes and impacts of human disturbance on birds, but little is known about how these impacts vary among habitats. This is of applied importance both for predicting bird responses to changes in disturbance and in planning how to reduce disturbance impacts. The Dartford Warbler Sylvia undata , a key heathland breeding species, occupies territories in a range of heathland types. Three territory habitat groups were identified: heather-dominated territories, heather territories with significant areas of European Gorse Ulex europaeus and territories containing Western Gorse U. gallii . Productivity was significantly affected by the timing of breeding in all habitats, but disturbance only appeared to have a significant impact on the productivity of birds in heather territories. Disturbance events in heather territories delayed breeding pairs for up to 6 weeks. This significantly decreased both the number of successful broods raised and the average number of chicks fledged per pair. Nests situated close to territory boundaries in heather territories, with high numbers of disturbance events, were more likely to fail outright. It was determined that an average of between 13 and 16 people passing through a heather territory each hour would delay breeding pairs sufficiently to prevent multiple broods.