دانلود رایگان مقاله انگلیسی تهدید احتمالی مرگ و میر در جمعیت خفاش های مهاجر توسط توربین های بادی - الزویر 2017

abstract

Large numbers of migratory bats are killed every year at wind energy facilities. However, population-level impacts are unknown as we lack basic demographic information about these species. We investigated whether fatalities at wind turbines could impact population viability of migratory bats, focusing on the hoary bat (Lasiurus cinereus), the species most frequently killed by turbines in North America. Using expert elicitation and population projection models, we show that mortality from wind turbines may drastically reduce population size and increase the risk of extinction. For example, the hoary bat population could decline by as much as 90% in the next 50 years if the initial population size is near 2.5 million bats and annual population growth rate is similar to rates estimated for other bat species (λ = 1.01). Our results suggest that wind energy development may pose a substantial threat to migratory bats in North America. If viable populations are to be sustained, conservation measures to reduce mortality from turbine collisions likely need to be initiated soon. Our findings inform policy decisions regarding preventing or mitigating impacts of energy infrastructure development on wildlife.

4. Discussion

Reports of large numbers of bats killed at wind energy facilities have attracted conservation attention for the past decade (Kunz et al., 2007). However, the lack of basic demographic information about bats in general and migratory bats specifically, has hindered our ability to empirically address whether bat fatalities from wind energy developments presents a serious threat to the viability of these species (Diffendorfer et al., 2015). Likewise, few studies have directly estimated populationlevel impacts from mortality from wind turbines on bird populations (Carrete et al., 2009; Schaub, 2012; Stewart et al., 2007), although numerous studies have documented collision rates for both birds and bats (see Arnett et al., 2016; Erickson et al., 2014 for recent reviews). We parameterized population models using a range of values from expert elicitation and informed from empirical estimates from other bat species and show that, across a range of plausible demographic scenarios, current mortality from wind turbines could result in rapid and severe declines of bat populations within 50 years and increased risk of extinction in 100 years. For hoary bat populations to sustain stable, persisting populations with levels of mortality from wind turbines current through 2014 in North America, the mean annual population growth rate must be substantially higher than what appears most likely from both the expert elicitation exercise and empirical estimates from other bat species. While two experts provided demographic estimates that produced robust population growth rates (λ = 1.16 and λ = 1.18; i.e., growth rates of 16–18% more bats per year) and a few empirical estimates were similarly high (Fig. 5), the median values of λ from published studies and expert opinion (λ = 1.0025 and λ = 1.015, respectively) suggest much more modest population growth rates that were sufficient for stable populations in the absence of wind energy associated mortality but that are too low to sustain the level of observed mortality currently caused by wind turbines.