The GWCT has done no research into the conservation impact of wind farms. The views that follow are based on a review of wind farm research conducted by others, combined with a knowledge of moorland management for wildlife acquired through our own research.
The GWCT’s 2011 report Waders on the Fringe highlights the conservation benefits brought by predator control on grouse moors for upland wading birds. However, grouse shooting in many cases shares the use of upland areas with other income-generating activities, notably grazing, forestry, recreation and power generation. These activities can have many impacts, both on carbon balances and the visual attractiveness of the landscape. However, when conducted in an imbalanced manner, there is historic evidence and some research data that any of these activities can threaten the viability of a grouse moor and thus the protection of heather habitats and upland bird populations. The most contemporary land use to emerge in the uplands is wind farms.
Research and anecdote suggests wind farms may impact on upland birds in the UK in three ways:
Negative impacts are most often caused by the construction of turbine bases and tracks, which can destroy nesting and foraging areas for moorland wildlife. Positive impacts may occur through improved access leading to increased investment in heather management by grazing and fire, resulting in better short-term plant food quality and provision of grit for grouse.
Some bird and bat species have direct or soaring flight, which makes them vulnerable to collision with turbines. Indirect positive impacts for ground-nesting birds may be seen where there is increased investment in predator and disease control aided by improved road access.
Displacement of birds as a result of disturbance (indirect loss of habitat)
Adult birds may be disturbed from nesting and foraging during construction and subsequent operations. Better access may lead to greater disturbance by the public but may also help channel access onto certain roads. The young of site-faithful (philopatric) species may choose not to recruit back to the site, leading to decreasing numbers over time. There may be an indirect positive impact on ground-nesting species through reduced harassment and predation by soaring raptors.
Winners and losers
Whether species lose or gain from wind farms at a population level depends on whether their ecology and local status allows them to exploit the positive impacts and whether they are behaviourally capable of exploiting any suitable habitat in the surrounding area. Correlative studies and anecdote suggest that where the income from a wind farm is re-invested in moorland management, the improved infrastructure on the moor can bring benefits to red grouse populations and thus probable benefits to mountain hares, black grouse and wading birds.
Species with low reproductive rates, soaring flight or species that have clear flightlines between particular habitats, such as divers, appear consistently vulnerable at individual and thus population levels. Notably soaring birds of prey such as eagles, harriers and buzzards appear to experience high rates of collision risk and consequently avoid wind farms, thus losing foraging habitat. Recently RSPB research from Scotland indicates that construction of individual wind farms can also be associated with declining numbers of golden plover and curlew. The reasons are suggested to be the immediate loss of habitat due to construction and long-term failure to recruit young birds as breeders.
The impacts of individual wind farms can be mitigated by locating them in areas away from the main nesting areas for upland waders or raptors and introducing grouse-moor-type management of habitat and predators in areas surrounding the wind farm. The GWCT through Hugo Straker has been active in this area already.
The increasing concern is that although individual wind farm developments in Scotland are subject to individual mitigation requirements, there is no requirement to consider the cumulative impact of a series of individual developments on bird populations at landscape scales. For example, home ranges of eagles may cease to provide viable foraging habitat if several wind farms block access to feeding areas of birds constrained to forage around nest sites. Similarly, the ability to mitigate the impacts on waders of individual developments may be reduced if the area surrounding the development decreases through subsequent developments.
The most recent RSPB research suggests that the effect of turbines is insignificant for most UK upland bird species more than 0.5km away from the turbine, but there was no assessment of how effective mitigation management might have been on the sites studied. Caution is required because previous RSPB research identifying areas of potential sensitivity for birds in Scotland assumed much larger ‘buffer’ zone effects: 6km for golden eagles and 1.5km for black grouse. There is no experimental research available to suggest what size the ‘buffer’ area has to be around wind farms to allow population-scale mitigation.
Glasgow University and the RSPB are working on models of cumulative effects of impacts of wind farms on bird populations and their regional population sizes. They are also seeking to include wind farm impacts in a more general model of impacts of habitat fragmentation in upland landscapes on bird populations.
GWCT policy takes a broad overview, and does not deal with landscape quality issues:
- Individual wind farm developments where there are large areas (as yet unquantified) of surrounding moorland and where driven grouse moor management (burning and predator control) are improved or developed within and surrounding the wind farm are likely to have a neutral or possibly long-term beneficial impact on red and black grouse, heather habitats, mountain hares, upland wading birds and raptors.
- Wind farm developments are increasingly likely to have negative impacts on upland bird populations the closer they are located together, regardless of mitigation measures. The exact impacts of this cannot yet be quantified, but requires Government to view wind farm development at the landscape scale rather than at the scale of the individual holding.
- In order to quantify and allow GWCT to offer advice on points made above, research (long-term monitoring and experimental management) should be undertaken to identify the size of the buffer area required to allow mitigation measures such as habitat and predator control to offset the on-farm population declines in wildlife.
- Country agencies should fund this research and, in the interim, include input from GWCT advisory staff in assessments for wind farm developments. GWCT policy staff should relay concerns about the lack of information on which to base mitigation options to Government.
Dr. Adam Smith
- Pearce-Higgins et al. (2009). The distribution of breeding birds around upland wind farms. Journal of Applied Ecology 46:1323-1331.
- Bright et al. (2008). Map of bird sensitivities to wind farms in Scotland: A tool to aid planning and conservation. Biological Conservation 141: 2342-2356.
- Fletcher et al. (2010). Changes in breeding success and abundance of ground-nesting moorland birds in relation to the experimental deployment of legal predator control. Journal of Applied Ecology 47: 263-272.
- Scottish Natural Heritage: Onshore wind energy