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

Abstract

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.

The rocks are hotter on the other side of the fence: roadside habitats should inform mitigation design

“…While small sample sizes require caution, our study does not claim any novel discoveries regarding timber rattlesnake spatial ecology, habitat selection, or thermal biology. Our observations are consistent with the ecology of the species established by decades of past field research (Reinert, 1984;Reinert et al, 1984;Reinert and Zappalorti, 1998;Waldron et al, 2006;Gardner-Santana and Beaupre, 2009;Nordberg et al, 2021;Tipton et al, 2023), including our observations of field active body temperatures and roadside habitat use (Reinert and Zappalorti, 1998;Gardner-Santana and Beaupre, 2009). Yet, our study is valuable to the road ecology conversation because it is among few that have examined the intersection of spatial, thermal, and road ecology (e.g., Peaden et al, 2017).…”

“…However, carcasses of turtles and large snakes were easily visible on the road because the surface of the highway was still relatively new, providing visual contrast (Supplementary Figure 7). Correlated random walk simulations indicated that rattlesnake movements were consistent with road avoidance (Supplementary Materials), which echoes numerous studies where timber rattlesnakes have demonstrated an aversion to crossing roads based on experimental trials (Andrews and Gibbons, 2005) and telemetry data collected in road fragmented landscapes (Nordberg et al, 2021;Tipton et al, 2023). Road avoidance in other species has been shown to scale with the road size and traffic intensity (Brehme et al, 2013), and the NVBP is a four-lane divided highway, with high traffic volumes (exceeding 17,000 vehicles per day) traveling at high speeds (112 km/hr).…”

Ophidiomycosis in a Timber Rattlesnake, Crotalus horridus (Linnaeus 1758), with behavioral and thermal observations: A case report from Georgia, USA

“…Wildlife Management Area (WMA) in Central Georgia that was included in a radio telemetry study since 2020 (Tipton et al 2023). Snakes in this population also have been monitored since 2021 for Oo.…”