Map of bird sensitivities to wind farms in Scotland: A tool to aid planning and conservation

Government targets for renewable energy have led to a huge increase in wind farm proposals. Because of its high wind resource, Scotland has more proposed wind farms than any other UK country. Scotland’s upland habitats support many birds of conservation concern, leading to potential conflict with wind farms.To help reduce this conflict, a map of bird sensitivities has been created to guide the location of onshore wind farms in Scotland, based on distributions of 16 bird species of conservation priority and statutory Special Protection Areas. The likely sensitivity of each species to wind farms was assessed from literature, based on foraging ranges, collision risk and sensitivity to disturbance. This information was used to buffer species’ locations to identify areas of ‘high’ or ‘medium’ sensitivity. Individual species maps were converted to 1-km square resolution, and a composite map for all species created by selecting the highest sensitivity rating for each square.The map indicates greater bird sensitivity in northwest Scotland, particularly the Highlands, Western and Northern Isles. Overall, 37% of Scotland is classified as ‘high’, 25% as ‘medium’ and 38% as ‘low/unknown’ sensitivity. The overlap of the mapped species with proposed and existing wind farm developments was assessed and species for which cumulative effects of multiple wind farms are of particular concern identified. Within a Scottish context, bean goose, red kite and hen harrier showed the greatest overlap. Applications and limitations of the approach are discussed.     

The effects of persecution on age of breeding and territory occupation in golden eagles in Scotland

Several studies have documented negative effects of persecution by humans on the population dynamics of large birds of prey. Several areas have seen a reduction in persecution in modern times, but the demography of large raptors still makes these birds vulnerable to such effects. In a GIS analysis, utilising data collected during two national censuses of the golden eagle Aquila chrysaetos in Scotland and contemporary data on the distribution of poisoning incidents (a common method of raptor persecution in Scotland), we show that persecution was associated with a reduction in the age of first breeding, territory vacancies, and the use of territories by non-breeding immatures. Persecution was therefore reducing adult survival and distribution and was probably creating ecological traps that attract mobile immatures, increasing subadult mortality in birds that may originate from persecution-free areas. Mapping a form of land management unique to moors managed for red grouse Lagopus lagopus scoticus shooting, where most poisoning occurs, we also show similar associations between golden eagle demography and grouse moor management. As such, persecution may be having a major impact on the golden eagle population of Scotland, since it occurs over a wide area and at least in some areas has continued unchecked over many decades.     

A conservation framework for the golden eagle in Scotland: Refining condition targets and assessment of constraint influences

Conservation strategies have three elements: species protection, site protection and, the most challenging component, conservation in the wider environment. Watson and Whitfield [Watson, J., Whitfield, P., 2002. A conservation framework for the golden eagle Aquila chrysaetos in Scotland. Journal of Raptor Research 36(1 Suppl.), 41-49.] proposed a conservation framework for the golden eagle in Scotland whose main innovation, taking a lead from EU conservation Directives, was to incorporate the concept of favourable condition and its maintenance by implementing conservation policies that are regionally targeted at known constraints in the wider environment. Three criteria were suggested to judge favourable condition: a national abundance target of breeding pairs, national and regional targets for breeding productivity, and regional targets for the extent of suitable habitat which is occupied by breeding pairs. Here we refine these criteria, first to take the national abundance target and use it to set regional targets. Distribution targets were implicitly incorporated by this process because abundance targets were set regionally, with regard to the proportion of known territories which should be occupied. This allowed us to dispense with the distribution criterion as originally proposed. Our next refinement was to base regional demographic targets not only on breeding productivity, but also on indirect measures of survival (which are likely to have more influence on population dynamics). Despite apparent overall population stability over the last 20 years, the national golden eagle population failed to meet the abundance target and only 3 of 16 regions where eagles have occupied territories since 1982 were considered to be in favourable condition. The key constraint preventing favourable condition being met was persecution, predominantly in some areas managed for grouse shooting. The advantages of a conservation framework over similar approaches, such as species action plans, are highlighted.     

Adaptive range selection by golden eagles in a changing landscape: A multiple modelling approach

Land abandonment is causing considerable woodland expansion in many mountainous areas of Europe, with potential repercussions on conservation-sensitive species typical of open habitats. We examined the potential impact of such changes on an alpine golden eagle population, by estimating the ranges potentially used by the eagles for foraging through different techniques (concentric circles of different radii and a tessellation-method based on telemetry data). Compared to randomly located territories, eagles selected ranges farther away from conspecifics, characterised by a rugged topography and rich in main prey species and in open habitats favoured by their main prey species, such as grassland, shrubs, xerophytic vegetation and rocky outcrops. Similarly, nest spacing and breeding success were related to the availability of optimal foraging habitats, also favoured by the main prey species of the eagles. Even though woodland-variables did not enter any of the stepwise models, eagles were dependent on grassland habitats, currently lost to woodland at a rate of about 0.5-1% per year, and on shrub vegetation rapidly evolving into woodland, which accounted on average for almost 10% of the eagle ranges. Long-term loss of such habitat may imply up to a 66% woodland increase for some eagle ranges. Given the complexity of the uncovered relationships and difficulty to make firm predictions, subsidies to halt the abandonment of traditional agro-pastoral practices seem urgently needed.     

A nine-year study of successful breeding in a Bonelli’s eagle population in southeast Spain: a basis for conservation

We analyse the factors influencing breeding success in a healthy population of Bonelli’s eagle (Hieraaetus fasciatus) from south-east Spain, a raptor that has suffered a serious decline in Europe. Between 18 and 33 pairs were annually monitored during the period 1994-2002. Several factors that may affect four breeding parameters were studied, namely human presence, vegetation, relief, climatic factors, intra- and inter-specific relationships, diet, prey abundance, nest building, adult mortality and age of reproduction. A consistently high breeding success was registered during the study period (productivity=1.43, SD=0.11), which was probably the result of high adult survival, adequate prey availability and mild weather conditions. However, a certain vulnerability to the presence of golden eagles (Aquila chrysaetos) and to human disturbance was observed. One interesting result was the reduced survival of young chicks on north-facing cliffs owing to colder conditions, which may partially explain the decline of the Bonelli’s eagle populations along its European distribution limits. We discuss the role of this healthy subpopulation in an Iberian metapopulation context, and propose that the potential interference of golden eagles should be taken into account when designing management strategies for Bonelli’s eagles. Finally, we pinpoint some conservation priorities and the importance of reducing the main causes of adult mortality (i.e. shooting and electrocution) to assure successful reproduction and survival of this species.     

Reduced breeding success in white-tailed eagles at Smøla windfarm,western Norway,is caused by mortality and displacement

Climate change scenarios and efforts to reduce CO₂ emissions have increased the focus on wind power and other renewable energy sources. Despite producing “clean” electricity, windfarms do have impacts on the environment. We studied the impact from a coastal windfarm on the breeding success of white-tailed eagles (Haliaeetus albicilla) at Smøla, western Norway by means of a BACI (before–after–control–impact) approach. The objective was to compare pre- and post-construction breeding success. A 10 year dataset from 47 eagle territories were analyzed using a generalized linear mixed model. Successful breeding was used as a response variable, while distance to turbines, distance to roads and before/after turbine construction were used as predictors. There was a significant effect of the interaction between time period and distance to turbines, showing that territories within 500 m from the turbines in the post-construction period experienced significantly lower breeding success than the same territories before construction. We found that this effect was most likely due to territories being vacated. The results emphasize the importance of using a BACI approach when assessing possible effects from wind-power production on breeding birds, especially for species breeding at low densities. It also emphasizes the importance of conducting thorough pre-construction studies on vulnerable bird species.     

Regional conservation priorities for a large predator: golden eagles (Aquila chrysaetos) in the Alpine range

We compared the density of golden eagles (Aquila chrysaetos) and their nest dispersion, productivity and diet in Alpine and pre-Alpine areas. The comparison was made at two spatial scales: (1) at the territory level within two contiguous populations, and (2) at the population level, using published data for 22 populations scattered across four countries (France, Switzerland, Germany and Italy). Availability of golden eagle's main prey species was higher in Alpine than in pre-Alpine regions. The potential foraging ranges of pairs of eagles in the pre-Alps had larger amounts of woodland and lower amounts of suitable foraging habitat than those of Alpine pairs. At both spatial scales, density and productivity were lower in the pre-Alps. Also, pre-Alpine populations were characterised by a lower percentage of main prey species in the diet, which was significantly correlated with productivity, and by a higher breadth of diet, which was negatively correlated with density. Overall, higher prey availability and habitat suitability in the Alps resulted in higher density and breeding success, in a manner compatible with theoretical metapopulation models. We suggest that priority be given to conservation of eagle populations in high quality Alpine habitat, and that conservation action be carried out by a mixture of site-protection measures and conservation of the wider environment.     

Identifying suitable habitat for dispersal in Bonelli’s eagle: An important issue in halting its decline in Europe

Bonelli’s eagle (Hieraaetus fasciatus) is an endangered bird of prey that is suffering a rapid decline in most of its distribution range in Europe. The aim of this study is to identify suitable areas used by juvenile eagles during their dispersal phase. Knowing the location of these target areas will help to plan adequate conservation programs to reduce the high juvenile mortality rates this species is suffering presently. The combined use of radio-telemetry for identifying core areas, Generalised Linear Models (G.L.M.) for producing predictive mathematical models and Geographic Information Systems (G.I.S.) for transferring predictive models into digital cartography predict well the presence of juvenile Bonelli’s eagles in dispersal areas. We built three different Generalised Lineal Models using topography, land-use/land-cover and human disturbance as explanatory variables. Our sample units were 11 settlement areas used by juvenile eagles during dispersal and 11 other areas within available habitat generated at random. Settlement areas were identified as the core areas used by radio-tagged eagles monitored during their first years of life. Immature eagles preferred habitats with greater percentages of pasture within the circular sampling area. Topographic features showed that the most intensively used areas by immature birds were generally steeper southeast-facing slopes. Settlement areas were also situated farther from villages and roads than expected. The land-use model performed well classifying correctly 85.9% of cases validated using a data-splitting strategy. The topographic model also performed well, classifying correctly 81.39% of cases validated by the same methodology. Predictive cartography showed suitable dispersal areas within potential juvenile distribution ranges that enable more efficient design of special conservation programmes.     

Satellite tracking of breeding black storks Ciconia nigra: new incomes for spatial conservation issues

Satellite tracking of black storks was used to estimate home range sizes and to study habitat selection during the breeding season. Breeding and non-breeding adults foraged over very large areas (ca. 54 000 ha for 12 territories), preferentially in woodlands with high number of river sources, mirroring the species needs for high quality water resource. Rearing and post-fledging ranges of breeding partners largely overlapped. Home ranges of non-breeding adults largely overlapped ranges of breeding birds, so that assessing home range size of breeding pairs from observed densities is not reliable. Protection and management of breeding and feeding habitats appear to be the most important conservation measures to be considered. This study allowed to evaluate how large these protected areas should be, and which habitat types they should encompass. Conservation measures for the species in western Europe should include protection of very large forest areas and also focus on managing river networks to ensure a high water quality as far as 20 km away from nests.     

Prey density, prey detectability and food habits: the case of Bonelli’s eagle and the conservation measures

In the diet of raptors the presence of prey-species is influenced by their abundance and the ground-level vegetation in territories, this situation being analysed for the Bonelli’s eagle (Hieraaetus fasciatus) in south-eastern Spain. First, the minimum number of prey-items for the reliability of results was tested, obtaining between 15 and 30 prey-items depending of pair. Second, differences in prey frequency and productivity among pairs was analysed, finding an interpair shift in both variables, but there was no relationship between the frequency of prey-species in the diet and productivity. Third, it was found that the percentage of European wild rabbit in the diet was less correlated with its abundance in territories than with the surface of open land in the same. This suggests that accessibility to rabbits would be more important for the Bonelli’s eagle that the absolute abundance of this prey type. Thus, open land is the single variable selected by a multiple multiple-regression analysis explaining the frequency of rabbits in this raptor’s diet. Birds as prey complemented the diet when open-land scarcity in the territories implies low rabbit detectability and consumption. Conservation measures proposed concerning the increase of prey availability in this declining population should consider both the absolute prey density and prey detectability, avoiding extensive reforestation in territories and favouring vegetation structure suitable for prey detection by eagles.     

Modelling the effects of persecution on the population dynamics of golden eagles in Scotland

We used observations of the age structure and breeding productivity of the Scottish population of golden eagles Aquila chrysaetos together with the classic theory of population dynamics to derive current `unmanipulated' estimates of life history parameters. We then used regional differences in age structure associated with differences in persecution intensity to derive estimates of prospective `persecution-free' life history parameters. The different parameter combinations were entered into a population model to simulate their effects on the number of occupied territories over time. Most simulations suggested that with unmanipulated demographic parameters the population should decline. The disparity between these predictions and the observed apparent stability in occupied territories was ascribed to the buffering effect of a lowering in age of breeding in areas where persecution is most intense and that more favourable parameter estimates within the estimated limits may be more realistic. The results indicated, nevertheless, that currently the population is vulnerable to decline as also suggested by the apparent lack of adults to occupy vacant territories. In the absence of the estimated 3-5% annual adult mortality through persecution, modelling suggested the population would increase. Removing estimated effects of persecution on reproductive rate and preadult survival were on their own insufficient to reverse the declines predicted from unmanipulated parameters, although the effect of persecution on preadult survival may be more severe than we estimated. In the absence of persecution we conclude that the population could expand to fill currently vacant but apparently suitable habitat and have a more secure long-term status.     

Modelling human impacts on the Tasmanian wedge-tailed eagle (Aquila audax fleayi)

The wedge-tailed eagle is Australia’s largest bird of prey and one of the largest eagles in the world. Aquila audax fleayi is an endemic Tasmanian subspecies isolated for 10,000 years from the nominate subspecies on the Australian mainland. The Tasmanian wedge-tailed eagle is classified nationally and at a State level as endangered due to its small number of breeding pairs, low breeding success and high rate of mortality from unnatural causes. The subspecies experiences mortality throughout its range from shooting, poisoning, trapping, road accidents, electrocutions and collisions with wind turbines, aircraft, fences and overhead wires, which we term ‘un-natural mortality’. A portion of the subspecies’ range is managed for timber production, which can lead to disturbance of nest sites and the loss of nest trees. We use a model of the eagle population from the Bass District in northeast Tasmania to explore the relative importance of different sources of mortality and nesting habitat loss, and the potential for mitigating impacts associated with unnatural mortality, disturbance, nesting habitat loss and human access to forests. We create a habitat map including suitable nest sites and link it to a dynamic landscape population model based on life history traits and disturbance responses. Using the program RAMAS-Landscape, we model alternative forest management scenarios, ranging from no timber harvesting and a natural wildfire regime, to scenarios prescribing native forest harvesting and regeneration and different levels of conversion of native forest to plantation under the same natural wildfire regime. The results indicate that the Tasmanian wedge-tailed eagle is sensitive to unnatural mortality, plantation establishment and native forest harvesting. The predicted decline over the next 160 years (65%) will most likely be driven largely by loss of current and potential future nest sites associated with harvesting activities, exacerbated by unnatural mortality in the wider landscape. Interventions that minimise unnatural mortality, reduce nest disturbance, and retain breeding habitat and nest sites may improve the prospects for the subspecies in the Bass District. If nest disturbance and unnatural mortality continue at the rates modelled here, the species appears to face a high risk of declining substantially in the region.     

Large scale risk-assessment of wind-farms on population viability of a globally endangered long-lived raptor

Wind-farms receive public and governmental support as an alternative energy source mitigating air pollution. However, they can have adverse effects on wildlife, particularly through collision with turbines. Research on wind-farm effects has focused on estimating mortality rates, behavioural changes or interspecific differences in vulnerability. Studies dealing with their effects on endangered or rare species populations are notably scarce. We tested the hypothesis that wind-farms increase extinction probability of long-lived species through increments in mortality rates. For this purpose, we evaluate potential consequences of wind-farms on the population dynamics of a globally endangered long-lived raptor in an area where the species maintains its greatest stronghold and wind-farms are rapidly increasing. Nearly one-third of all breeding territories of our model species are in wind-farm risk zones. Our intensive survey shows that wind-farms decrease survival rates of this species differently depending on individual breeding status. Consistent with population monitoring, population projections showed that all subpopulations and the meta-population are decreasing. However, population sizes and, therefore, time to extinction significantly decreased when wind-farm mortality was included in models. Our results represent a qualitative warning exercise showing how very low reductions in survival of territorial and non-territorial birds associated with wind-farms can strongly impact population viability of long-lived species. This highlights the need for examining long-term impacts of wind-farms rather than focusing on short-term mortality, as is often promoted by power companies and some wildlife agencies. Unlike other non-natural causes of mortality difficult to eradicate or control, wind-farm fatalities can be lowered by powering down or removing risky turbines and/or farms, and by placing them outside areas critical for endangered birds.     

Variations in the age of mates as an early warning signal of changes in population trends? The case of Bonelli's eagle in Andalusia

Methods to evaluate population trends have recently received particular attention because of the decreasing patterns shown by several species since the nineteenth century. We have studied demographic traits of the Bonelli's eagle (Hieraaetus fasciatus) population of Andalusia (southern Spain) for 20 years (1980-2000). This species is endangered and is suffering a rapid decline in most of its distribution range. Although our study population has remained stable for the last 10 years, both age at first breeding and productivity have decreased during the last 5 years. We propose that age at first breeding could be used as a potential early warning signal to detect possible future changes in population trends of long-lived species with deferred maturation age. In particular, in this species spatial variation in demographic traits could help to detect whether unnatural events such as shooting are decreasing age at first breeding and productivity. If occupation of territories by non-adults is caused by human persecution, conservation efforts in the particular case of Bonelli's eagle have to be directed to protect those breeding territories where an increase in the percentage of pairs containing at least one non-adult individual would be detected.     

Lead concentrations in bones and feathers of the globally threatened Spanish imperial eagle

Raptors that consume game species may ingest lead fragments or shot embedded in their prey’s flesh. Threatened Spanish imperial eagles Aquila adalberti feed on greylag geese in southern Spain in winter, and often ingest lead shot. We analysed bone and feather samples from 65 Spanish imperial eagle museum specimens collected between 1980 and 1999, to investigate the prevalence of elevated lead concentrations. Four of 34 birds (12%) had very elevated bone lead concentrations. All four birds were young and the concentrations were outliers to the distribution, suggesting probable exposure to lead gunshot. Excluding these elevated lead outliers, bone lead concentrations were correlated with the bird’s age at death. Three of 41 feathers (7%) had elevated lead concentrations, indicative of high exposure during feather formation. When these outliers were omitted, feather lead concentration was correlated with the age of museum specimens, suggesting that a high proportion of feather lead was exogenous, deposited after specimen collection. Therefore, careful interpretation of feather lead concentrations is required to separate endogenous and exogenous lead. We discuss the potential significance of lead poisoning in Spanish imperial eagles and other raptors, and recommend measures for its reduction.     

Protecting more than the wetland: The importance of biased sex ratios and habitat segregation for conservation of the Hine’s emerald dragonfly, Somatochlora hineana Williamson

Within species habitat use may depend on age, season or sex of an individual. The distribution of males and females may vary both temporally and spatially due to differences in the costs of reproduction and the distribution of critical resources. Conservation of a species requires knowledge of the habitat use of both sexes in order to predict the population size and protect all habitats that a species requires. Adult dragonfly populations often have highly male-biased sex ratios at the breeding habitat. This bias has been attributed to females using alternative habitats to avoid male harassment, or to high female mortality. We monitored adult Hine’s emerald dragonfly (Somatochlora hineana Williamson) populations, in breeding and non-breeding habitats in Door County, Wisconsin and found significant differences in habitat use between males and females. Males primarily used wetland habitats, while females primarily used dry meadows and marginal breeding habitats, only coming into wetlands to lay-eggs or find mates. We assessed food resources in the different habitats and found that high quality insect prey (primarily adult Diptera) were more available in the wetland habitat, indicating that these areas were likely a more productive foraging area for adult dragonflies. The fact that females appear to avoid the wetland habitat is consistent with the hypothesis that male harassment alters female distribution patterns. Consideration of the patterns of habitat use by S. hineana indicates the need to develop a broader understanding of the importance of non-wetland areas in the conservation of wetland species.     

宁夏农牧区荒漠化草场风能发电提水模式资源评估

利用风速观测资料研究分析了宁夏广武荒漠化草场风速变化规律,对风能密度、有效风速小时数、风能发电量和提水量进行估算,并提供了不同时期可能灌溉量与灌溉面积。结果表明广武年均有效风能密度为120W/m~2,属全国风能资源区划一般区内,年均有效风能储量为562kW·h/m~2,3～20m/s有效风速累积4680h,属风能资源可利用区,不利于发展大中型风电,但适合风电井灌提水的家庭经营小型农牧场,其风能资源可使广武额定功率2kW的风力机抽水2.0～5.2m~3/h,可满足2～7hm~2人工草场或农田生长季灌溉用水,解决农牧区生活用电和人畜饮水。     

Designing a network of marine reserves in the Mediterranean Sea with limited socio-economic data

The present study is the first to determine priorities for the location of marine reserves using spatial prioritization software in the eastern Mediterranean Sea. We used biophysical data from visual census surveys on: fish species abundance, presence of various habitat types, and percent coverage of seagrasses and canopy algae. Efficient conservation planning requires spatially explicit information on how proposed management will affect stakeholders, which in this region was very limited. We created novel socio-economic cost indices to account for fisheries and tourists. Our fishing metrics were based on fisher behaviour including information on the location of ports and areas often inaccessible to fishers due to high wind exposure. We developed a cost index for tourism based on the availability of beds for tourists. We examined how the spatial priorities for marine reserves varied using different combinations of these socio-economic cost metrics. We found about 17% of sites were a high priority regardless of which cost metric was used. We also compared, for the first time in the Mediterranean, our results devised using systematic conservation planning approaches with priorities developed by two non-systematic methods, the Natura 2000 proposed marine reserves and sites that local fishers proposed for protection. Only a few sites identified by our approach were the same as those recommended as part of Natura 2000 or the fishers’ proposals. This suggests that much more work is needed to harmonise existing proposals with the principles of efficient systematic conservation planning.     

Where new farm woodlands support biodiversity action plans: a spatial multi-criteria analysis

In many developed countries forest cover is growing and the provision of non-market benefits is increasingly important for forestry management. The benefits provided by a new woodland not only depend on the design of the woodland (local site level), but also on its location in the wider landscape. This paper develops a generic GIS-based method to map the potential biodiversity benefits of new woodlands through an integration of species-habitat modelling for a list of 15 key species derived from a “Local Biodiversity Action Plan”, encompassing the Northeast of Scotland, and spatial multi-criteria analysis. For each selected species ‘Preferred Future Woodland’ maps are produced, indicating the extent to which populations of these species are expected to expand or contract in response to further afforestation. Species are then weighted on the basis of criteria of relative scarcity of suitable habitat and national importance of the regional population. The maps are then combined using this weighting to yield an overall potential biodiversity benefit map, which shows that the areas with the highest potential biodiversity gains are the edges of major agricultural areas (mostly deciduous), the riparian zones (deciduous) and areas adjacent to mature native pine woods (coniferous). It is demonstrated that the use of this map for more explicit spatial targeting of an existing farm afforestation scheme can help to provide much more ‘biodiversity value’ for taxpayers’ money.     

Higher breeding densities of the threatened little bustard Tetrax tetrax occur in larger grassland fields: Implications for conservation

Previous studies have found that densities of little bustard Tetrax tetrax breeding males tend to be higher in areas with smaller agricultural fields, presumably due to increased habitat diversity. However, exceptionally high densities have been found in large grassland fields in Portugal, which suggests that the influence of field size varies geographically, and that the role of this factor is not yet fully understood, despite its importance as a key management issue.We studied how field size, together with vegetation structure, influences the presence and density of breeding little bustards in a region of southern Portugal. Fifty-four grassland fields were sampled in 2007 and another 29 in 2008, with sizes ranging from 23 to 172 ha. A total of 183 breeding males were found in 47 of these fields, reaching densities of up to 37 males/100 ha. A higher probability of occurrence of breeding males was found in larger fields with a vegetation height below 40 cm and field size alone explained 46% of the variability in male density. These results suggest that larger continuous areas of suitable habitat attract many males, most likely as a consequence of their lek mating system. We conclude that conservation efforts, in a landscape context of large farm sizes, should: (1) be channelled to farms with large fields; (2) ensure adequate livestock grazing to create suitable habitat and (3) promote management at a landscape level to ensure the most continuous grassland habitat patches possible.