Using motion-sensor camera technology to infer seasonal activity and thermal niche of the desert tortoise (Gopherus agassizii)

Agha, Mickey; Augustine, Benjamin; Lovich, Jeffrey E.; Delaney, David K.; Sinervo, Barry; Murphy, Mason O.; Ennen, Joshua R.; Briggs, Jessica; Cooper, Robert J.; Price, Steven J.

doi:10.1016/j.jtherbio.2015.02.009

Cited by 14 publications

(11 citation statements)

References 71 publications

(75 reference statements)

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“…We deployed all cameras at approximately the same time, and straight‐line distance between cameras ranged from approximately 8 m to 2,471 m. We mounted cameras on 1.5‐m tall stakes positioned 1 m from desert tortoise burrow entrances. Consequently, the camera detection zone was approximately 2–4 m 2 , allowing us to see the entrance of the burrow and a small extent of the surrounding landscape (Agha et al ). To avoid camera sensitivity bias, we set all cameras to motion activation via an infrared sensor with high motion sensitivity and programmed them to take a series of 3 high‐definition photographs at a trigger speed of 0.2 seconds, following methods and procedures from Rovero et al ().…”

Section: Methodsmentioning

confidence: 99%

“…Every 15–30 days, an investigator checked each camera and downloaded photos. Using long‐term desert tortoise data from Mesa (1997–2013; Lovich et al , Agha et al ), we noted the date when the burrow was first recorded as occupied by a radio‐telemetered desert tortoise, providing an approximate minimum time since first known occupation or rough approximation for age of the burrow. As a result of our methods for determining camera locations, all monitored burrows were occupied at some point in the past 2 years by tracked desert tortoises.…”

Section: Methodsmentioning

confidence: 99%

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Mammalian mesocarnivore visitation at tortoise burrows in a wind farm

et al. 2017

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There is little information on predator–prey interactions in wind energy landscapes in North America, especially among terrestrial vertebrates. Here, we evaluated how proximity to roads and wind turbines affect mesocarnivore visitation with desert tortoises (Gopherus agassizii) and their burrows in a wind energy landscape. In 2013, we placed motion‐sensor cameras facing the entrances of 46 active desert tortoise burrows in a 5.2‐km2 wind energy facility near Palm Springs, California, USA. Cameras recorded images of 35 species of reptiles, mammals, and birds. Counts for 4 species of mesocarnivores at desert tortoise burrows increased closer to dirt roads, and decreased closer to wind turbines. Our results suggest that anthropogenic infrastructure associated with wind energy facilities could influence the general behavior of mammalian predators and their prey. Further investigation of proximate mechanisms that underlie road and wind turbine effects (i.e., ground vibrations, sound emission, and traffic volume) and on wind energy facility spatial designs (i.e., road and wind turbine configuration) could prove useful for better understanding wildlife responses to wind energy development. © 2017 The Wildlife Society.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Mammalian mesocarnivore visitation at tortoise burrows in a wind farm

et al. 2017

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“…To identify the temporal variation in road crossing frequency, we fit mixture models to observed road crossings (e.g., Owen-Smith et al, 2012;Agha et al, 2015). These models allowed us to parse out periods of increased road crossing activity during the primary active season for desert tortoises.…”

Section: Analyses Of Road Crossingsmentioning

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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“…Camera traps have been used in many different types of ecosystems including semi-arid grasslands such as the Serengeti [ 8 ], mountainous regions such as the Himalayas [ 9 ], and tropical forests such as the Amazon rainforest [ 10 ]. Camera traps are also commonly used in desert systems such as the deserts of California, USA [ 11 – 13 ].…”

Section: Introductionmentioning

confidence: 99%

“…This species is listed, endangered, and often at low population densities [ 29 , 32 ]. Camera traps are often used as a method of detection for endangered species [ 8 , 10 , 11 ]. The spatial partitioning of deserts into shrub-open habitat classes is a common method used to study positive interactions in deserts [ 33 ].…”

Section: Introductionmentioning

confidence: 99%

A picture is worth a thousand data points: an imagery dataset of paired shrub-open microsites within the Carrizo Plain National Monument

Noble

Lortie

Westphal

et al. 2016

GigaSci

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BackgroundCarrizo Plain National Monument (San Joaquin Desert, California, USA) is home to many threatened and endangered species including the blunt-nosed leopard lizard (Gambelia sila). Vegetation is dominated by annual grasses, and shrubs such as Mormon tea (Ephedra californica), which is of relevance to our target species, the federally listed blunt-nosed leopard lizard, and likely also provides key ecosystem services. We used relatively nonintrusive camera traps, or trail cameras, to capture interactions between animals and these shrubs using a paired shrub-open deployment. Cameras were placed within the shrub understory and in open microhabitats at ground level to estimate animal activity and determine species presence.FindingsTwenty cameras were deployed from April 1st, 2015 to July 5th, 2015 at paired shrub-open microsites at three locations. Over 425,000 pictures were taken during this time, of which 0.4 % detected mammals, birds, insects, and reptiles including the blunt-nosed leopard lizard. Trigger rate was very high on the medium sensitivity camera setting in this desert ecosystem, and rates did not differ between microsites.ConclusionsCamera traps are an effective, less invasive survey method for collecting data on the presence or absence of desert animals in shrub and open microhabitats. A more extensive array of cameras within an arid region would thus be an effective tool to estimate the presence of desert animals and potentially detect habitat use patterns.

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Using motion-sensor camera technology to infer seasonal activity and thermal niche of the desert tortoise (Gopherus agassizii)

Cited by 14 publications

References 71 publications

Mammalian mesocarnivore visitation at tortoise burrows in a wind farm

Mammalian mesocarnivore visitation at tortoise burrows in a wind farm

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

A picture is worth a thousand data points: an imagery dataset of paired shrub-open microsites within the Carrizo Plain National Monument

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