Reconciling endangered species conservation with wind farm development: Cinereous vultures (Aegypius monachus) in south-eastern Europe
Graphical abstract
Introduction
Harnessing wind energy is a rapidly expanding sector of the renewable energy industry, which is considered to be technologically mature and financially profitable, while receiving increasing public and governmental support (Abbasi et al., 2014). Although harnessing wind energy is often recognized as an environmentally friendly strategy to combat climate change, it is not without adverse environmental impacts, in particular for bats and birds, which are prone to collision with wind turbine blades (Abbasi et al., 2014, Georgiakakis et al., 2012). Raptors and old world vultures are known to be especially vulnerable to collision due to their flight behaviour, to an extent where fatalities may be high and population persistence threatened (Carrete et al., 2012, de Lucas et al., 2012, Gove et al., 2013, Martínez-Abraín et al., 2012, Sanz-Aguilar et al., 2015). As pressure for new wind farm projects increases, a development versus conservation conflict can arise, which can be increasingly aggravated when the effects of development projects accumulate (Bastos et al., 2015).
To resolve such conflicts, a suite of legislative tools are available in the European Union (EU), which support the conservation of vulnerable bird species (EC, 2009), safeguard the sustainable spatial planning of development projects through a Strategic Environmental Assessment (SEA) process (EC, 2001), while improving the implementation of Environmental Impact Assessment (EIA) plans (EC, 2011). Despite the well-developed legislative framework for biodiversity conservation in the EU, EIA studies may be poorly implemented (Kati et al., 2015), while SEA processes have not been accomplished in several EU States when planning for wind power, aggravating the development-conservation conflict (Gove et al., 2013).
Wind farm spatial planning that avoids or minimizes adverse environmental effects requires replete data for several species' distributional patterns across a wide area to map ‘sensitivity’ (Bright et al., 2008, Dimalexis et al., 2010). Producing detailed species-specific sensitivity maps for raptors and vultures can be challenging because they may be at low density and/or range widely and so spatial modelling of their ranging behaviour can be a cost-effective tool at the scale required by SEAs (Madders and Whitfield, 2006, Obermeyer et al., 2011). So far, such models have mainly been built on empirical knowledge of ranging behaviours (Fielding et al., 2006, Tellería, 2009, Eichhorn et al., 2012, Tack and Fedy, 2015) and few studies have used remote telemetry, with its increasing utility through technological advances and its recognized capability to improve sensitivity mapping (Katzner et al., 2012, Reid et al., 2015). On their own, however, spatial models of ranging behaviour provide only a spatial measure of relative collision risk (Eichhorn et al., 2012).
A second approach employs collision risk models (CRMs) to predict collision mortality rates. CRMs combine three-dimensional records of bird flight activity in the vicinity of proposed turbines with the probability of collision for birds passing through the rotor swept volume, incorporating the physics of moving turbine blades with the size and flight speed of the target species (Band et al., 2007, Smales et al., 2013). An open-access and peer reviewed CRM is the “Band CRM” (Band et al., 2007, Chamberlain et al., 2006) which, as in all CRMs, has so far been restricted to specific wind farm projects during the EIA process (e.g. Chamberlain et al., 2006), and not to forecast collision mortality on a wider spatial scale.
Eichhorn et al. (2012) attempted for the first time to combine spatial models of bird flight activity with a CRM, but only simulated red kite Milvus milvus flight activity at a local scale. Here, we have advanced this approach, by combining spatial models of flight activity with a CRM over a larger scale (Schaub, 2012), so as to predict collision mortality at a level that can explore population consequences of strategic wind energy plans with greater rigour (Reid et al., 2015).
Our study area holds the sole Balkan breeding population of cinereous vulture (Aegypius monachus) and hosts several sites protected for bird interest (Dimalexis et al., 2010, Skartsi et al., 2008). Yet it is also identified as a top priority area for wind farm development by the Greek government, setting a target of establishing 960 MW in the near future (with operating wind farms of 253 MW, and 56 MW approved for construction), on the purported basis of a SEA (MEECC, 2007, RAE (Regulatory Authority for Energy), 2015). As such, the area provides an acute example of the potential for conflict between plans for extensive wind farm development and the conservation of a threatened species that is vulnerable to such development.
Our overall objective was to use telemetry data from cinereous vultures to develop tools that can be applied to resolve this specific Balkan conflict, and thereby illustrate how our approach could be widely adopted for sustainable spatial planning of development projects in a suite of conflicts in other similar situations. Our particular aims were: (1) to produce a sensitivity map for the whole population, combining the concepts of core area and relative spatial use, as a broad spatial guide to conservation prioritization and wind farm planning; (2) to estimate collision mortality for currently operating wind farms by combining spatial models of vulture flight activity with a CRM, as a basis for future consideration of the potential impact of planned wind farms.
Section snippets
Study area and species
The study area was located in the Eastern Rhodopes mountains in the Balkans (Fig. 1), covering parts of Greece and Bulgaria (15,000 km2). The climate is Continental–Mediterranean and the area is characterized by gentle topography up to 1000 m (mean altitude: 171 ± 117 SD). It comprises hills covered by broad-leaved and pine woods, alternating with pastures and agricultural mosaics (Vasilakis et al., 2008). It is a thinly populated area, and includes five sites of the Natura 2000 network of
Results
Our tracking datasets involved 19 cinereous vultures (18% of the population). It consisted of 367 bird-months, and comprised 21,599 locations. Adults were tracked for 49% of the monitoring time, immatures for 30%, juveniles for 19%, and fledglings for 2% (for details see Appendix A). Male: female ratio in our sample of tagged birds was 1:1.2, similar to the 1:1 ratio of our population (Poulakakis et al., 2008).
Spatial conservation prioritization
We found that cinereous vultures used a large foraging area far away from their breeding colony that is located within the DLS NP, with the population range including former nesting grounds in Bulgaria (Hristov et al., 2012, Skartsi et al., 2008).
Our results clearly showed that the population core area enveloped most operational wind turbines. The population core area was much larger than expected if a standard 50% use threshold was used, and accounted for a large part of the population range
Conclusions
Predicted losses to the Balkan cinereous vulture population were sufficient to cause concern over wind farm impact. At only 24 breeding pairs and facing several other anthropogenic threats, the population is vulnerable without additional pressure through turbine collision mortality. Future wind energy development plans, if enacted without accounting for environmental impacts, would probably endanger the population's existence per se. Our study allows such impacts for cinereous vultures to be
Acknowledgments
We are grateful to T. Skartsi, P. Babakas, J. Elorriaga, B. Cárcamo, S. Stoychev and S. Avramov for their great contribution to fieldwork and general support in all stages of the present research, as well as to the numerous European Voluntary Service (WWF) volunteers taking part in fieldwork. Fieldwork was conducted also by Bulgarian Society for the Protection of Birds and Green Balkans. Fieldwork and equipment were funded primarily by WWF Greece and also by the Recreation and Development Union
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