Rowena H. W. Langston

Collision Effects of Wind-power Generators and Other Obstacles on Birds

There is extensive literature on avian mortality due to collision with man‐made structures, including wind turbines, communication masts, tall buildings and windows, power lines, and fences. Many studies describe the consequences of bird‐strike rather than address the causes, and there is little data based on long‐term, standardized, and systematic assessments. Despite these limitations, it is apparent that bird‐strike is a significant cause of mortality. It is therefore important to understand the effects of this mortality on bird populations. The factors which determine avian collision risk are described, including location, structural attributes, such as height and the use of lighting, weather conditions, and bird morphology and behavior. The results of incidental and more systematic observations of bird‐strike due to a range of structures are presented and the implications of collision mortality for bird populations, particularly those of scarce and threatened species susceptible to collisions, are discussed. Existing measures for reducing collision mortality are described, both generally and specifically for each type of structure. It is concluded that, in some circumstances, collision mortality can adversely affect bird populations, and that greater effort is needed to derive accurate estimates of mortality levels locally, regionally, and nationally to better assess impacts on avian populations. Priority areas for future work are suggested, including further development of remote technology to monitor collisions, research into the causes of bird‐strike, and the design of new, effective mitigation measures.

Space Partitioning Without Territoriality in Gannets

This Is the Place Bats, bees, seals, and many seabirds practice central-place foraging, leaving a central home site, such as a hive or a rookery, to forage in a specific territory. Such species also share the challenge of competing for local resources with individuals from separate colonies. Using satellite tags, Wakefield et al. (p. 68, published online 6 June; see the Perspective by Weimerskirch) followed over 180 northern gannets to determine potential drivers of foraging territory division. Boundaries among colonial territories arose as a result of competition with individuals from other territories. Individuals from the same colony appeared to share information about foraging sites, presumably contributing to the establishment and maintenance of specific, long-term colonial territories. Gannets establish foraging territory boundaries in colonies through local competition and information exchange. [Also see Perspective by Weimerskirch] Colonial breeding is widespread among animals. Some, such as eusocial insects, may use agonistic behavior to partition available foraging habitat into mutually exclusive territories; others, such as breeding seabirds, do not. We found that northern gannets, satellite-tracked from 12 neighboring colonies, nonetheless forage in largely mutually exclusive areas and that these colony-specific home ranges are determined by density-dependent competition. This segregation may be enhanced by individual-level public information transfer, leading to cultural evolution and divergence among colonies.

A guide to the provision of refuges for waders : an analysis of 30 years of ringing data from the Wash, England

1. It has been proposed to establish roost refuges to limit the disturbance to internationally important over-wintering populations of waders on the Wash. 2. Waders have been caught regularly on the Wash since 1959. By 1993, 24 576 oystercatchers, 4125 grey plovers, 38 041 knots, 96 801 dunlins and 11 729 redshanks had been ringed at 85 roost sites around the Wash. 3. Analysis of the movements between roosts provides a means of determining the relative mobility of waders and the effect of spacing on the availability of the proposed refuges to waders during normal roost movements. This analysis does not take into account either movements between feeding sites nor between roosting and feeding sites. 4. The Wash was divided into five sections according to observed wader movements between roosts and feeding grounds. At least 79% of inter-roost movements of oystercatchers, grey plovers, knots, dunlins and redshanks within a year were restricted to a single section. Juvenile waders changed section more frequently than adults. Waders were almost as site faithful between-year as within-year. 5. A model, based on the variation in retrap rate with distance of the three least mobile wader species within a section of the Wash, was used to describe wader dispersal between roosts. The model was then used to estimate the effect of interrefuge distance on the proportion of waders reaching at least one refuge during normal roost movements. 6. Between roosts waders dispersed over short distances within a section of the Wash. Placing refuges 2, 4 and 7 km apart for grey plovers, 2.5, 5 and 10 km apart for dunlins within-year, and 3.5, 5.5 and 9.5 km apart for redshanks put the refuges within reach of 90, 75 and 50% of the respective populations of these species during their normal roost movements. To validate the sectional approach, the analysis was repeated using roosting movements of dunlins over another section and over the whole Wash; the results were similar to those obtained in the original analysis. 7. The implications of wader dispersal for refuge creation are discussed.

Changes in the numbers of breeding waders on lowland wet grasslands in England and Wales between 1982 and 2002

Capsule Lapwing, Snipe, Curlew and Redshank decreased significantly between 1982 and 2002, while over the same period Oystercatcher increased. Aims To provide current status and population trends for waders breeding on lowland wet grassland in England and Wales. Methods Waders were counted and mapped on three visits to 1051 lowland wet grassland sites, between April and June 2002. Data were compared with those gathered using identical methods in a survey in 1982 and related to land use characteristics and conservation designation. Results Between 1982 and 2002 there were significant declines of 38% for Lapwing Vanellus vanellus, 61% for Snipe Gallinago gallinago, 40% for Curlew Numenius arquata and 29% for Redshank Tringa totanus. Oystercatcher Haematopus ostralegus increased significantly by 47% in the same period. Populations of all species were highly aggregated with most of the birds found on a small number of key sites. Site designation was found to be an important predictor of breeding wader distribution, density and density change. Conclusions The marked population declines of four grassland wader species over the last 20 years are of considerable concern. Careful management of nature reserves and other key sites is essential to halt these declines, while wider scale and more carefully targeted agri-environment schemes may hold the key to reversing declines in the longer term. The efficacy of site designation and current agri-environment schemes for conserving breeding waders on wet grasslands needs to be reviewed.

Territory selection by the Dartford warbler (Sylvia undata) in Dorset, England: the role of vegetation type, habitat fragmentation and population size

The Dartford warbler (Sylvia undata) is of conservation concern throughout western Europe. In the UK conservation is centred on management of the warblers lowland heath habitat. This study analysed the warblers habitat requirements in Dorset, its UK population centre. Maps of breeding territories from 1974, 1984 and 1994 were linked to maps of heathland vegetation and adjacent land use from 1978, 1987 and 1996. Logistic regression showed territories were positively associated with the area of dry/humid heath, mature Ulex europaeus, bare soil, and more rarely with wet heath, young U. europaeus, U. gallii and Pinus scrub. There were negative responses to fragmentation (isolation and area of a heath), and the proximity of woodland, urban areas and intensive agriculture. Sub-optimal habitat was used in years of high population size. Habitat management for this species should consider not only heathland vegetation but also landscape factors such as fragmentation and the proximity of avoided land use types.

Lack of sound science in assessing wind farm impacts on seabirds

Lack of sound science in assessing wind farm impacts on seabirds Rhys E. Green*, Rowena H. W. Langston, Aly McCluskie, Rosie Sutherland and Jeremy D. Wilson Conservation Science Group, Department of Zoology, University of Cambridge, David Attenborough Building, Pembroke Street, Cambridge CB2 3QZ, UK; RSPB Centre for Conservation Science, RSPB, The Lodge, Sandy Bedfordshire SG19 2DL, UK; and RSPB Centre for Conservation Science, RSPB Scotland, 2 Lochside View, Edinburgh Park, Edinburgh EH12 9DH, UK

The breeding status of the Ring Ouzel Turdus torquatus in the UK in 1999

Capsule The first co-ordinated census of breeding Ring Ouzels across the UK reports a minimum of 6157 (95% CI, 3586–9372) and a maximum of 7549 (95% CI, 4459–11197) territories. Aims To set a baseline for the future monitoring of breeding Ring Ouzels and to provide a systematically based estimate of the population size. Methods A random sample of tetrads (2 × 2 km squares) was surveyed from the known breeding range (as defined from the two national breeding bird atlases of 1968–72 and 1988–91). The survey method used tape playback and observation and involved walking four parallel transects in each tetrad. Results Tape playback accounted for one-third of the territories located. Of the tetrads surveyed that were known to be occupied during the 1988–91 breeding bird atlas, 39–43% were unoccupied in 1999. Conclusion The survey highlights a continuing contraction in range.

Status of breeding Twite Carduelis flavirostris in the UK

Capsule The first comprehensive estimate of breeding Twite in the UK indicates that there were approximately 10 000 pairs in 1999. Aims To provide a baseline population estimate of breeding Twite in the UK. Methods In Scotland and England, three visits were made in May to July to a stratified random sample of 1-km squares, walking modified point transects, at 200-m intervals. Whilst recording was continuous, at 100-m intervals within suitable breeding habitat, observers made five-minute stops to scan and listen for Twite. Habitat cover was recorded to the nearest 10%. Supplementary records were collated from Wales and Northern Ireland. Several methods were used to produce population estimates, with bootstrapped confidence intervals. Results There were an estimated 10 000 pairs of breeding Twite in the UK in 1999, with the range lying between 6000 and 15 000 pairs. The majority, 9948 (95% confidence intervals 6293–14 586) pairs, was recorded in Scotland and England. Conclusions The population estimate provides a baseline for future surveys, although similar surveys are required in Wales and Northern Ireland (or all of Ireland) for completeness. A three-visit protocol is suggested for future surveys. There is accumulating evidence for the continued decline of Twite breeding range and numbers in the UK.

Future Research Directions to Reconcile Wind Turbine–Wildlife Interactions

Concurrent with the development of wind energy, research activity on wind energy generation and wildlife has evolved significantly during the last decade. This chapter presents an overview of remaining key knowledge gaps, consequent future research directions and their significance for management and planning for wind energy generation. The impacts of wind farms on wildlife are generally site-, species- and season-specific and related management strategies and practices may differ considerably between countries. These differences acknowledge the need to consider potential wildlife impacts for each wind farm project. Still, the ecological mechanisms guiding species’ responses and potential vulnerability to wind farms can be expected to be fundamental in nature. A more cohesive understanding of the causes, patterns, mechanisms, and consequences of animal movement decisions will thereby facilitate successful mitigation of impacts. This requires planning approaches that implement the mitigation hierarchy effectively to reduce risks to species of concern. At larger geographical scales, population-level and cumulative impacts of multiple wind farms (and other anthropogenic activity) need to be addressed. This requires longitudinal and multiple-site studies to identify species-specific traits that influence risk of mortality, notably from collision with wind turbines, disturbance or barrier effects. In addition, appropriate pre- and post-construction monitoring techniques must be utilized. Predictive modelling to forecast risk, while tackling spatio-temporal variability, can guide the mitigation of wildlife impacts at wind farms.

Reconciling Biodiversity Conservation and Widespread Deployment of Renewable Energy Technologies in the UK

Renewable energy will potentially make an important contribution towards the dual aims of meeting carbon emission reduction targets and future energy demand. However, some technologies have considerable potential to impact on the biodiversity of the environments in which they are placed. In this study, an assessment was undertaken of the realistic deployment potential of a range of renewable energy technologies in the UK, considering constraints imposed by biodiversity conservation priorities. We focused on those energy sources that have the potential to make important energy contributions but which might conflict with biodiversity conservation objectives. These included field-scale solar, bioenergy crops, wind energy (both onshore and offshore), wave and tidal stream energy. The spatially-explicit analysis considered the potential opportunity available for each technology, at various levels of ecological risk. The resultant maps highlight the energy resource available, physical and policy constraints to deployment, and ecological sensitivity (based on the distribution of protected areas and sensitive species). If the technologies are restricted to areas which currently appear not to have significant ecological constraints, the total potential energy output from these energy sources was estimated to be in the region of 5,547 TWh/yr. This would be sufficient to meet projected energy demand in the UK, and help to achieve carbon reduction targets. However, we highlight two important caveats. First, further ecological monitoring and surveillance is required to improve understanding of wildlife distributions and therefore potential impacts of utilising these energy sources. This is likely to reduce the total energy available, especially at sea. Second, some of the technologies under investigation are currently not deployed commercially. Consequently this potential energy will only be available if continued effort is put into developing these energy sources/technologies, to enable realisation of their full potential.