Camera-trap Basking Arrays Detect Western Chicken Turtles (Deirochelys reticularia miaria) in Dynamic Ephemeral Wetland Mosaics

Authors: Brandon C. Bowers, Corey M. Fielder, Danielle K. Walkup, Roel R. Lopez, Wade A. Ryberg, Toby J. Hibbitts, Mickey R. Parker, Paul S. Crump

Landscapes dominated by ephemeral wetlands vary in both space and time as temperature and precipitation vary regionally, seasonally, and annually (Niemuth et al. 2010). Regionally, the size, density, and spatial configuration of ephemeral wetland complexes are determined by where rain falls and is diverted, creating large wetland complexes following flood events or smaller complexes following wandering seasonal storms (Niemuth et al. 2010; Vanderhoof et al. 2016). Locally, individual ephemeral wetlands exhibit an array of sizes and shapes and vary in permanence with temperature and precipitation (Euliss et al. 2014), creating drying gradients across the landscape among wetlands, but also within them, from highly ephemeral edges to more permanent wetland centers (Gabrielsen et al. 2016). For species dependent on ephemeral wetland complexes, these spatial and temporal dynamics continually alter the location, size, density, and spatial configuration of suitable habitat (Herfindal et al. 2012; Gabrielsen et al. 2022). For biologists studying species dependent on ephemeral wetland complexes, these spatial and temporal dynamics continually alter the location, number, type, density, and spatial configuration of sites needed to sample suitable habitat for the target species, which can be unmanageable to track when sampling methods involve intensive trapping.

Semiaquatic freshwater turtles, in particular, often inhabit ephemeral wetland complexes and can be difficult to study, because individuals frequently make far-ranging terrestrial movements among many wetlands for mating, foraging, basking, aestivating, and overwintering purposes (Bennett et al. 1970; Buhlmann and Gibbons 2001). These ecological attributes make semiaquatic freshwater turtles vulnerable at multiple scales, from individual road mortality to large-scale habitat loss (Buhlmann and Gibbons 2001; Gibbs and Shriver 2002), consequently resulting in the need for population monitoring at multiple scales for management, conservation, or restoration goals (e.g., Ryberg et al. 2017). Population monitoring of semiaquatic freshwater turtles traditionally involves invasive trapping with baited or unbaited hoop nets (Brown et al. 2011), deployment of basking traps (Gamble 2006), or less invasive visual encounter surveys using spotting scopes and binoculars (Lindeman 1999). Sampling turtles across large, dynamic, ephemeral wetland complexes with these traditional monitoring methods can be time-consuming and expensive, but camera traps have recently become a cheap, efficient, non-invasive, automated alternative to studying turtle movements and basking (Mali et al. 2016; Unger and Santana 2019), nesting and aestivation (Geller 2012; Bowers et al. 2021b), and detection/survival (Bluett and Schauber 2014). Herein, we assess the efficacy of a relatively inexpensive camera-trap basking array designed to move up and down with the changing water levels of ephemeral wetlands occupied by Western Chicken Turtles (Deirochelys reticularia miaria; Fig. 1A, B), a subspecies under review for protection under the U.S. Endangered Species Act (USFWS 2011).

Suggested Citation