Mortality at wind-farms is positively related to large-scale distribution and aggregation in griffon vultures

Abstract

a b s t r a c t Wind-farms have negative impacts on the environment, mainly through habitat destruction and bird mortality, making it urgent to design predictive tools to use in landscape planning. A frequent assumption of wind-farm assessment studies is that bird distribution and abundance and bird mortality through collision with turbines are closely related. However, previous results are contradictory and question the usefulness of these variables to select safer wind-farm locations. We focused on a species highly vulnerable to collision at wind-farms, the griffon vulture, to test whether mortality at turbines was related to the relative position of turbines within the vulture population. We used the location of all turbines on 34 wind-farms in southern Spain, details on 342 griffon vultures found dead, and the location and size of breeding colonies and roost sites of the species during the breeding and non-breeding seasons, respectively. Using variables that describe the large-scale distribution and aggregation of vultures, we found that year-round mortality at turbines increased when they were located in highly populated areas, a result that can be translated into management guidelines to plan wind-farm locations.Bird abundances can help to guide wind-farm plans at large scales. Current protocols of counting birds at specific points during particular periods of time have low predictive power. However, other more integrative cues such as the spatial distribution and aggregation of some vulnerable species should be used as criteria for large-scale environmental planning. Local inspection of the relationship between mortality at existing turbines and their relative position within the spatial distribution of bird populations can guide managers in planning future wind-farms and in managing currently operating developments..

Using risk prediction models and species sensitivity maps for large-scale identification of infrastructure-related wildlife protection areas: The case of bird electrocution

“…However, systematic area-selection processes have seldom been used to locate high-risk mortality areas to protect wildlife from human impacts, such as roads, wind farms, or bird electrocutions on power lines (e.g. Malo et al, 2004;Langen et al, 2009;Carrete et al, 2012;Santos et al, 2013). The implementation of systematic area-selection processes combining spatial risk models of wildlife mortality at a large spatial scale with data on presence or abundance of species sensitive to such an impact would help to optimize mitigation of widespread human infrastructure impacts, especially those affecting a large number of species.…”

Optimizing Wind Power Generation while Minimizing Wildlife Impacts in an Urban Area

“…The assumption that density of bird activity at the area around the zone of the potential wind-turbine blades is proportional to the collision risk is implicit in almost any flight model study that attempts to relate flight behavior to collision risk without actual mortality data [23,34,35]. Studies that used collision-mortality observations to evaluate this assumption provide contradictory evidence -some found support to the positive relationship between abundance and/or activity density and mortality [8,39,40], while others find poor relation- Fig. 1).…”

“…The best location for a wind turbine, while considering wildlife risk in a limited space of an urban or rural community, will have high wind power potential and low risk of bird mortality. Unfortunately, wildlife mortality rates due to wind turbines are known to be location and species specific [8,22,[25][26][27][28]. Additionally, it is impossible to predict actual mortality rates before well-parameterized models of bird (or bat) movement that includes their location, height and activity [23,[34][35][36] exist for all species in the area.…”

“…Typical economic considerations for wind farm locations are driven by long term wind statistics and expected energy output [1][2][3][4], interactions with other turbines [5,6], and turbine height [7]. Environmental considerations, including collision risk with birds and bats, also affects the locations for wind farms [2,3,[8][9][10][11][12][13].…”

“…Moreover, it is of particular interest to avoid hazards to wildlife, such as bird and bat collisions [8,[21][22][23][24][25][26][27][28].…”