ANNOUNCEMENTS
Economic growth and natural resource conservation are conflicting goals, whose reconciliation calls for sustainable development solutions. Modern societies are increasingly investing in renewable energies to reduce the depletion of fossil fuels and other adverse environmental impacts of conventional energy production. However, recent studies indicate negative impacts of wind and solar energy on biodiversity conservation that should be examined and incorporated in decision-making process. I assessed wind turbine induced bird mortality in a tropical arid landscape that is experiencing rapid expansion of renewable energy projects. I conducted the study during 2020 (Jan – May) in 3000 km2 Thar Desert landscape, Jaisalmer, India that included 900 wind turbines. To assess bird mortality, I searched carcasses along zigzag routes within 150 m radius around wind turbines, on three occasions. I compared the carcass encounter rate at wind turbines based on the first survey to that at control sites (28 150-m radius plots in similar habitat without turbines), to determine that carcasses around wind turbines did not result from natural mortality. I cleared of existing carcasses 30 days prior to the second and third wind turbine surveys, to ensure that fresh carcasses were deposited within this period. Since carcasses perish before the survey, I corrected for the decomposition/scavenging bias experimentally, by placing fresh carcasses that were a) monitored over time to estimate persistence probability using Kaplan Meier survival analysis. Subsequently, I estimated bias-adjusted bird mortality rates as carcass turbine-1 month-1. I explored the influence of wind-turbine type (single or cluster) and habitat characteristics on mortality using linear regression models and Information Theoretic Approach. I found 43 bird carcasses belonging to 3 families during wind turbine surveys, and none in control sites. Carcass encounter rates (turbine-1 month-1) was estimated at 0.09 (95%CI 0.45 –0.13). Median persistence time of carcass was 2 days. Thus, the probability of a carcass persisting until a survey, if deposited in the preceding month, was 0.435 (95%CI 0.38 –0.49). Incorporating this correction factor, true mortality rate was estimated at 0.21 (95% CI 0.107 – 0.331) turbine-1 month-1. Further, mortality rate depended on habitat, with death rates greater in woodland compared to barren areas. My results indicated adverse impacts of windturbines on bird populations, with expected annual mortalities of 2288 (SE 1158-3577) birds in the landscape. Large birds, particularly soaring raptors were vulnerable to wind turbines. This is a matter of conservation concern since this group is already on decline for various other reasons. However, the mortality rate at wind-turbines is substantially lower than that at power-lines in the same landscape (Uddin et al. 2020, ). This evidence calls for sensible planning of wind turbine installation such as avoiding high-priority conservation areas, and mitigation of associated powerlines by burying and marking with diverters, to reduce the cumulative impact of wind energy on wildlife. Based on this study, I recommend more stringent assessments of wind turbine impacts before they are sanctioned across wildlife habitats.
Keywords: wind turbines, collision, mortality, birds, desert landscape, carcass survey, renewable energy
