Sex, Mass, and Monitoring Effort: Keys to Understanding Spatial Ecology of Timber Rattlesnakes (Crotalus horridus)

Petersen, Christopher E.; Goetz, Scott M.; Dreslik, Michael J.; Kleopfer, John D.; Savitzky, Alan H.

doi:10.1655/d-18-00035

Cited by 10 publications

(12 citation statements)

References 42 publications

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“…Intrinsic factors, such as sex and motivational state, have pronounced effects on the movement patterns of pit vipers (Waldron et al, 2006;DeSantis et al, 2019;Emerson et al, 2022) and therefore are a key consideration when investigating the influence of roadways on C. horridus movement. For pit vipers, elevated male movement is thought to be the primary determinant of mate location and success, and this is thought to drive significant increases in movement and space use by males during the mating season (Waldron et al, 2006;Petersen et al, 2019). Given this male-search based mating system and observations made by previous authors on C. horridus elsewhere in their distribution, we expected males to generally display elevated measures of movement and space use relative to females (both within seasons and when data are pooled across seasons).…”

Section: Effect Of Roads On Annual Rt and Act Movement Measuresmentioning

confidence: 99%

“…However, numerous intrinsic and extrinsic factors simultaneously influence movement decisions, making it difficult to pinpoint the mechanistic roles of each individual driver. Among these, an individual's sex, age, and motivational state (e.g., behavioral season) have all been demonstrated to influence movement patterns, and, consequently, are important considerations when exploring the effects of individual extrinsic factors, such as roadways, on movement patterns (Waldron et al, 2006;Petersen et al, 2019). Unsurprisingly, species-specific behavioral responses to roadways can vary tremendously, ranging from avoidance (Thurber et al, 1994;Rondinini and Doncaster, 2002;Andrews et al, 2008;McGregor et al, 2008;Hibbitts et al, 2017) to strong attractance (Mumme et al, 2000;Aresco, 2005).…”

Section: Introductionmentioning

confidence: 99%

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Scale-dependent effects of roadways on the movement behavior of a large-bodied pit viper (Crotalus horridus)

Tipton

Vázquez-Diosdado²,

DeSantis³

2023

Front. Ecol. Evol.

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Roadways are among the most widespread and disruptive anthropogenic land use features that influence the behavior and movement of wildlife. Negative impacts of roadways have been well documented, but the behavioral impact of roadways on smaller, cryptic species has yet to be thoroughly examined. Using a novel integration of radio telemetry and tri-axial accelerometry, we evaluated the effects of roadways on the movement behavior of 26 adult Timber Rattlesnakes (Crotalus horridus) at coarse and fine time scales in central Georgia between June 2020 and November 2021. To interpret the effect of roads at a coarse time scale, we modeled the effect of mean annual distance to roadways (DTR) on annual measures of movement and space use by C. horridus using both radio telemetry and accelerometry derived metrics (RT and ACT metrics). To explore the fine-scale impact of roadways, we quantified RT and ACT metrics during confirmed road interactions (i.e., instances when individual snakes crossed a road or encountered a road but did not cross) and compared these instances to the RT and ACT metrics calculated across the remainder of the active season within this subset of snakes. Relating the annual RT and ACT metrics to DTR revealed no significant associations at a coarse time scale. However, the evaluation of C. horridus movement behavior during punctuated road encounters revealed that snakes increased RT and ACT metrics during the road interactions compared to metrics calculated across the remainder of the active season. This might indicate that the abundance of contiguous habitat adjacent to roadways at our study site is serving as an adequate buffer to any long-term shifts in movement behavior, but the potential hidden cost of increasing movement when snakes encounter roads could have negative implications for populations that encounter roads more frequently, even in the absence of significant direct road mortality. Overall, integrating radio telemetry and accelerometry and adopting a scale-dependent approach to quantifying movement allowed for a more detailed evaluation of the response of C. horridus to roadways. This approach holds promise for detecting and interpreting previously overlooked short-term alterations in snake movement behavior with potentially significant fitness consequences.

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Section: Effect Of Roads On Annual Rt and Act Movement Measuresmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Scale-dependent effects of roadways on the movement behavior of a large-bodied pit viper (Crotalus horridus)

Tipton

Vázquez-Diosdado²,

DeSantis³

2023

Front. Ecol. Evol.

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“…The MCP method has long been lauded as a way of maintaining comparability and historical consistency with previous studies [ 56 ], yet has well documented issues: extreme sensitivity to sampling size and tracking duration [ 57 ], and overestimated boundary delineation [ 58 ], with the inclusion of areas that the animals never use [ 59 , 60 ]. However, Row and Blouin-Demers [ 18 ] argued that MCPs are preferable to kernel density estimators specifically for herpetofauna, and MCPs’ use persists for comparisons in reptile telemetry studies [ 61 ]. An additional and considerable limitation of MCPs is that they do not create a probabilistic utilization distribution.…”

Section: Methodsmentioning

confidence: 99%

Reptiles on the wrong track? Moving beyond traditional estimators with dynamic Brownian Bridge Movement Models

et al. 2020

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Background Animal movement expressed through home ranges or space-use can offer insights into spatial and habitat requirements. However, different classes of estimation methods are currently instinctively applied to answer home range, space-use or movement-based research questions regardless of their widely varying outputs, directly impacting conclusions. Recent technological advances in animal tracking (GPS and satellite tags), have enabled new methods to quantify animal space-use and movement pathways, but so far have primarily targeted mammal and avian species. Methods Most reptile spatial ecology studies only make use of two older home range estimation methods: Minimum Convex Polygons (MCP) and Kernel Density Estimators (KDE), particularly with the Least Squares Cross Validation (LSCV) and reference (href) bandwidth selection algorithms. These methods are frequently applied to answer space-use and movement-based questions. Reptile movement patterns are unique (e.g., low movement frequency, long stop-over periods), prompting investigation into whether newer movement-based methods –such as dynamic Brownian Bridge Movement Models (dBBMMs)– apply to Very High Frequency (VHF) radio-telemetry tracking data. We simulated movement data for three archetypical reptile species: a highly mobile active hunter, an ambush predator with long-distance moves and long-term sheltering periods, and an ambush predator with short-distance moves and short-term sheltering periods. We compared traditionally used estimators, MCP and KDE, with dBBMMs, across eight feasible VHF field sampling regimes for reptiles, varying from one data point every four daylight hours, to once per month. Results Although originally designed for GPS tracking studies, dBBMMs outperformed MCPs and KDE href across all tracking regimes in accurately revealing movement pathways, with only KDE LSCV performing comparably at some higher frequency sampling regimes. However, the LSCV algorithm failed to converge with these high-frequency regimes due to high site fidelity, and was unstable across sampling regimes, making its use problematic for species exhibiting long-term sheltering behaviours. We found that dBBMMs minimized the effect of individual variation, maintained low error rates balanced between omission (false negative) and commission (false positive), and performed comparatively well even under low frequency sampling regimes (e.g., once a month). Conclusions We recommend dBBMMs as a valuable alternative to MCP and KDE methods for reptile VHF telemetry data, for research questions associated with space-use and movement behaviours within the study period: they work under contemporary tracking protocols and provide more stable estimates. We demonstrate for the first time that dBBMMs can be applied confidently to low-resolution tracking data, while improving comparisons across regimes, individuals, and species.

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“…Our results further showed males occupying activity ranges 1.25-3.00 ha (82.6-186.5%) larger than those of females, and moving up to 6.24 m/d (88.9%) more than females. We expected these differences, as males of C. ruber elsewhere [49] and those of other rattlesnake species (e.g., [89][90][91][92][93]; but see [94]) exhibit greater levels of activity than females. Moreover, the activity range size increased with increasing SVL for male snakes, but not for female snakes.…”

Section: Translocation Effects On the Snakementioning

confidence: 99%

Human-Wildlife Conflict at a Suburban–Wildlands Interface: Effects of Short- and Long-Distance Translocations on Red Diamond Rattlesnake (Crotalus ruber) Activity and Survival

Corbit

Hayes

2022

Diversity

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The mitigation of human–rattlesnake conflicts often involves euthanizing or translocating the offending rattlesnake. Although translocation is generally considered more humane, especially by the general public, it may negatively impact the translocated individual and may not be effective if that individual returns to areas where the probability of human conflict is high. We used radiotelemetry to experimentally study the effects of short- (SDT) and long-distance translocation (LDT; beyond the typical home range or activity range) on adult Red Diamond Rattlesnakes (Crotalus ruber) near a residential development in Southern California. Though the results were mixed, some analyses suggested that higher numbers of SDTs were associated with larger activity areas and increased movement. For snakes undergoing LDT, the activity areas and mean daily movement distances were 1.8–4.6 times larger than those of non-LDT snakes in the year of translocation, but were similar in the following year. Cox regression models revealed that, for both LDT and non-LDT snakes, every 1 m increase in the distance moved resulted in a 1.2% decreased risk of moving back into a human-modified area and a 1.6% decreased risk of returning to the original site of conflict. We failed to detect an effect of either LDT or SDT on body mass change or survival. Our findings suggest that LDT of nuisance snakes may be a viable option for at least some rattlesnake populations or species, especially those in which individuals do not require communal overwintering sites.

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Sex, Mass, and Monitoring Effort: Keys to Understanding Spatial Ecology of Timber Rattlesnakes (Crotalus horridus)

Cited by 10 publications

References 42 publications

Scale-dependent effects of roadways on the movement behavior of a large-bodied pit viper (Crotalus horridus)

Scale-dependent effects of roadways on the movement behavior of a large-bodied pit viper (Crotalus horridus)

Reptiles on the wrong track? Moving beyond traditional estimators with dynamic Brownian Bridge Movement Models

Human-Wildlife Conflict at a Suburban–Wildlands Interface: Effects of Short- and Long-Distance Translocations on Red Diamond Rattlesnake (Crotalus ruber) Activity and Survival

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