Mitigation-driven translocation effects on temperature, condition, growth, and mortality of Mojave desert tortoise ( Gopherus agassizii ) in the face of solar energy development

Brand, Laurie A.; Farnsworth, Matthew L.; Meyers, J. D.; Dickson, Brett G.; Grouios, Christopher; Scheib, Amanda F.; Scherer, Rick D.

doi:10.1016/j.biocon.2016.05.032

Cited by 20 publications

(21 citation statements)

References 32 publications

(85 reference statements)

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“…; Brand et al. ) was consistent with these findings: translocated tortoises in the Ivanpah Valley exhibited increased movement and experienced higher ambient temperatures than did resident and control tortoises in the months immediately post‐translocation. We found that those short‐term behavioral and environmental impacts on translocated tortoises did not result in increased mortality in the 5 years over which individuals were monitored.…”

Section: Discussionsupporting

confidence: 59%

“…; Brand et al. ) and negatively influencing survival. However, this effect did not differentially affect translocated tortoises—despite their increased movements and time spent in high ambient temperatures during the months following translocation (Farnsworth et al.…”

Section: Discussionmentioning

confidence: 99%

“…; Brand et al. ). Based on these findings, we hypothesized that long‐term space‐use patterns and thermal conditions could still influence survival of translocated tortoises.…”

Section: Introductionmentioning

confidence: 98%

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Multiyear monitoring of survival following mitigation‐driven translocation of a long‐lived threatened reptile

Dickson

Scherer

Kissel

et al. 2019

Conservation Biology

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Translocation is used by managers to mitigate the negative impacts of development on species. Moving individuals to a new location is challenging, and many translocation attempts have failed. Robust, posttranslocation monitoring is therefore important for evaluating effects of translocation on target species. We evaluated the efficacy of a translocation designed to mitigate the effects of a utility‐scale solar energy project on the U.S. federally listed Mojave desert tortoise (Gopherus agassizii). The species is a long‐lived reptile threatened by a variety of factors, including habitat loss due to renewable energy development in the Mojave Desert and portions of the Colorado Desert in southern California (southwestern United States). We translocated 58 individual tortoises away from the project's construction site and intensively monitored them over 5 years (2012–2017). We monitored these individuals and tortoises located in the translocation release area (resident tortoises; n = 112) and control tortoises (n = 149) in a nearby location. We used our tortoise encounter data and known‐fate survival models to estimate annual and cumulative survival. Translocated tortoises in each of 2 size classes (120–160 mm, >160 mm) did not survive at lower rates than resident and control tortoises over the study period. For models with different sets of biotic and abiotic covariates, annual and cumulative estimates of survival were always >0.87 and >0.56, respectively. Larger tortoises tended to have higher survival, but translocated tortoises were not differentially affected by the covariates used to model variation in survival. Based on these findings, our translocation design and study protocols could inform other translocation projects for desert species. Our case study highlights the benefits of combining rigorous scientific monitoring with well‐designed, mitigation‐driven management actions to reduce the negative effects of development on species of conservation concern.

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Section: Discussionsupporting

confidence: 59%

Section: Discussionmentioning

confidence: 99%

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Multiyear monitoring of survival following mitigation‐driven translocation of a long‐lived threatened reptile

Dickson

Scherer

Kissel

et al. 2019

Conservation Biology

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“…The mean location error of the GPS loggers was 8.6 m (range 3-38 m) as determined by previous field trials. With desert ectotherms, behavioral thermoregulation within physiological limits is critical for movement, water balance, foraging efficiency, reproduction, and overall survival (Brand et al, 2016;Zimmerman et al, 1994;Nagy and Medica, 1986). Previously, carapace temperatures have been used as a proxy for internal body temperatures for the desert tortoise (Zimmerman et al, 1994;Brand et al, 2016).…”

Section: Data Collectionmentioning

confidence: 99%

“…With desert ectotherms, behavioral thermoregulation within physiological limits is critical for movement, water balance, foraging efficiency, reproduction, and overall survival (Brand et al, 2016;Zimmerman et al, 1994;Nagy and Medica, 1986). Previously, carapace temperatures have been used as a proxy for internal body temperatures for the desert tortoise (Zimmerman et al, 1994;Brand et al, 2016). To understand the thermal ecology of desert tortoises near and away from structures, we affixed iButton temperature loggers to the first right or first left costal scute of each study animal with epoxy putty (J-B Weld SteelStik).…”

Section: Data Collectionmentioning

confidence: 99%

Effects of roads and roadside fencing on movements, space use, and carapace temperatures of a threatened tortoise

Peaden

Nowakowski

Tuberville

et al. 2017

Biological Conservation

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A B S T R A C TRoads are widespread features of many landscapes that can negatively affect wildlife, most notably through animal-vehicle collisions. Roadside fencing has increasingly been installed to help eliminate this source of mortality. While fencing may reduce road mortality, other types of wildlife responses to this novel barrier are not well understood. Here, we examined the movement behavior, space use, and carapace temperatures of Mojave Desert Tortoises (Gopherus agassizii) as they interacted with a roadside fence and an unfenced road. Using GPS loggers, we tracked tortoise movements for two years at 15-min intervals. We found that carapace temperatures were greater near structures (fence or unfenced road) than away from structures; tortoises near the unfenced road had higher mean carapace temperatures, but tortoises along the fence experienced more extreme upper temperatures that approached the species' thermal limit. Movement speeds were also higher along the structures than away from them. Tortoise home range sizes decreased with proximity to the fence or road; fragmentation of home ranges and road-crossing avoidance may have contributed to smaller home ranges along the fenced and unfenced road, respectively. While tortoises crossed the road significantly less than expected by chance, they did so primarily in May and July and in areas with washes, indicating that placement of roadside fencing and animal underpasses could be optimized by targeting areas where roads intersect washes. Taken together, our results suggest that roadside fencing can affect behavior, space use, and thermal ecology of tortoises, which may require refinements to future conservation strategies involving roadside fencing.

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Using incidental mark‐encounter data to improve survival estimation

Harju¹,

Cambrin

Averill‐Murray

et al. 2019

Ecology and Evolution

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1. Obtaining robust survival estimates is critical, but sample size limitations often result in imprecise estimates or the failure to obtain estimates for population subgroups. Concurrently, data are often recorded on incidental reencounters of marked individuals, but these incidental data are often unused in survival analyses.2. We evaluated the utility of supplementing a traditional survival dataset with incidental data on marked individuals that were collected ad hoc. We used a continuous time-to-event exponential survival model to leverage the matching information contained in both datasets and assessed differences in survival among adult and juvenile and resident and translocated Mojave desert tortoises (Gopherus agassizii).3. Incorporation of the incidental mark-encounter data improved precision of all annual survival point estimates, with a 3.4%-37.5% reduction in the spread of the 95% Bayesian credible intervals. We were able to estimate annual survival for three subgroup combinations that were previously inestimable. Point estimates between the radiotelemetry and combined datasets were within |0.029| percentage points of each other, suggesting minimal to no bias induced by the incidental data.4. Annual survival rates were high (>0.89) for resident adult and juvenile tortoises in both study sites and for translocated adults in the southern site. Annual survival rates for translocated juveniles at both sites and translocated adults in the northern site were between 0.73 and 0.76. At both sites, translocated adults and juveniles had significantly lower survival than resident adults. High mortality in the northern site was driven primarily by a single pulse in mortalities. 5. Using exponential survival models to leverage matching information across traditional survival studies and incidental data on marked individuals may serve as a useful tool to improve the precision and estimability of survival rates. This can improve the efficacy of understanding basic population ecology and population monitoring for imperiled species.

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Mitigation-driven translocation effects on temperature, condition, growth, and mortality of Mojave desert tortoise ( Gopherus agassizii ) in the face of solar energy development

Cited by 20 publications

References 32 publications

Multiyear monitoring of survival following mitigation‐driven translocation of a long‐lived threatened reptile

Multiyear monitoring of survival following mitigation‐driven translocation of a long‐lived threatened reptile

Effects of roads and roadside fencing on movements, space use, and carapace temperatures of a threatened tortoise

Using incidental mark‐encounter data to improve survival estimation

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