Turbines and Terrestrial Vertebrates: Variation in Tortoise Survivorship Between a Wind Energy Facility and an Adjacent Undisturbed Wildland Area in the Desert Southwest (USA)

Abstract

With the recent increase in utility-scale wind energy development, researchers have become increasingly concerned how this activity will affect wildlife and their habitat. To understand the potential impacts of wind energy facilities (WEF) post-construction (i.e., operation and maintenance) on wildlife, we compared differences in activity centers and survivorship of Agassiz's desert tortoises (Gopherus agassizii) inside or near a WEF to neighboring tortoises living near a wilderness area (NWA) and farther from the WEF. We found that the size of tortoise activity centers varied, but not significantly so, between the WEF (6.25 ± 2.13 ha) and adjacent NWA (4.13 ± 1.23 ha). However, apparent survival did differ significantly between the habitat types: over the 18-year study period apparent annual survival estimates were 0.96 ± 0.01 for WEF tortoises and 0.92 ± 0.02 for tortoises in the NWA. High annual survival suggests that operation and maintenance of the WEF has not caused considerable declines in the adult population over the past two decades. Low traffic volume, enhanced resource availability, and decreased predator populations may influence annual survivorship at this WEF. Further research on these proximate mechanisms and population recruitment would be useful for mitigating and managing post-development impacts of utility-scale wind energy on long-lived terrestrial vertebrates.

Mammalian mesocarnivore visitation at tortoise burrows in a wind farm

“…A new cause of habitat alteration in the desert southwest, USA, is renewable energy development (Lovich and Ennen 2011, ). Habitat disturbance caused by wind energy facilities creates unique challenges and opportunities for wildlife (Lovich and Ennen , Agha et al ). Although wind energy facilities and associated infrastructure may create potential hazards for many species (Kuvlesky et al ), these facilities may also benefit others by restricting public access and limiting cultivation (Kelcey , Lovich and Daniels ).…”

Do terrestrial animals avoid areas close to turbines in functioning wind farms in agricultural landscapes?

“…Firstly, a positive impact may result from the fact that wind farms may reduce the presence of birds of prey both through direct mortality due to collisions and because they avoid foraging near wind turbines (Drewitt and Langston 2006; Garvin et al 2011; Kuvlesky et al 2007; Lovich 2015; Osborn et al 1998; Pearce-Higgins et al 2012; Smallwood 2007, 2013; Smallwood et al 2009). Consequently, animals living close to turbines may be under less pressure from avian predators (Agha et al 2015; de Lucas et al 2005; Winder et al 2014a, b). Secondly, we hypothesize that the availability of grit near turbines may be the most important attractant for pheasants, especially in winter.…”

“…Consequently, low-level impacts of wind farms during the operational phase were observed on the home ranges of large mammals and their behavior and nutritional ecology (Helldin et al 2012; Walter et al 2006). Previous studies have found both a significant effect of wind farms (Agha et al 2015; Lovich et al 2011; Rabin et al 2006) and no effects on medium-sized and small animals (de Lucas et al 2005; Ennen et al 2012; Łopucki and Mróz 2016; Winder et al 2014a, b). A limited number of studies conducted on a narrow group of species and species-specific differences in results do not allow reliable generalizations about the effects of wind turbines on terrestrial animals.…”

“…We decided to study a group of species that exhibit different ecology and food preferences because we expected that reactions to wind turbines (avoidance or preference of wind turbine proximity, or no effect) might be species specific, depending on prey or predator position in the food chain or predation risk. Some authors suggest that wind energy development affects local predator communities, resulting in an indirect effect of decreased predation risk for prey species (Agha et al 2015; Winder et al 2014a, b). The targeted species have home ranges large enough to show possible differences in their utilization of functioning wind farm areas.…”

Population‐level effects of wind farms on a desert lizard

“…Differences in habitat use and novel causes of mortality were identified at a single wind farm site (Lovich and Daniels , Lovich et al ). When compared with nearby natural areas, tortoises at wind farms had slightly larger activity areas, and significantly higher survival (Agha et al ). These effects may have been due to reduced mortality from predators and traffic, increased resource availability, and ease of movement at wind farms (Agha et al ).…”