Factors Affecting the Detection of an Imperiled and Cryptic Species

Abstract

Population surveying and monitoring are important for identifying conservation needs and tracking trends in populations, communities, and ecosystems over time and laying the groundwork for conservation management and policy decisions. If species or populations go undetected because of inadequate effort or sampling design, protection and management cannot be properly provided. Due to the widespread loss of populations, the Eastern Massasauga (a rattlesnake) was recently listed as a federally threatened species in the United States; it is also listed as threatened in Canada. Given its current conservation status, there is considerable interest at state and federal levels in determining how to best survey for Eastern Massasaugas to aid in management decisions. Using a 16-year dataset, we examined the relationships among environmental, temporal, area, management, and search effort factors on the detection probability of Eastern Massasaugas. We found that four abiotic parameters (solar irradiance, shaded air temperature, three-day maximum air temperature, and humidity) and three search parameters (effort per researcher, search area, and search time of day) influenced detection of Eastern Massasaugas. As the current biodiversity crisis continues, the cost-effective use of resources and scientific expertise will continue to increase in importance. We hope our results stimulate similar analyses in other taxa, which will be critical for designing and implementing regional survey and monitoring programs.

Combining surface and soil environmental DNA with artificial cover objects to improve terrestrial reptile survey detection

“…Visual counts under artificial cover objects (e.g., wood boards)––which attract individuals for use as protection or for thermo‐ and osmoregulation––are a standard survey method and provide a substantial boost to survey detection rates over conventional searching techniques for terrestrial reptiles (Hoare et al., 2009 ). Realized detection rates, however, are often still low enough that surveys do not provide adequate statistical power to accurately assess populations or habitat associations (Crawford et al., 2020 ; Matthias et al., 2021 ). Environmental DNA (eDNA) survey methods eliminate the need to directly observe the target organism, providing a larger window of time in which evidence of the species remains present and can be detected (Ficetola et al., 2019 ).…”

Estimating the complex patterns of survey availability for loggerhead turtles

“…Knowing more about the mechanistic processes may provide insights into future patterns with expected changes in climate (Santidrián Tomillo and Spotila 2020) and energy development scenarios (Bailey et al 2014, which urged mechanistic studies linked to wind development). Like other air‐breathing marine animals, patterns of sea turtle availability to visual observers may be related to a variety of predictive or explanatory variables including those related to migration, forage, and abiotic factors that affect sea turtle physiology (Crawford et al 2020).…”

Environmental DNA is effective in detecting the federally threatened Louisiana Pinesnake (Pituophis ruthveni)

“…eDNA analysis improved Burmese Python detection and occupancy estimates thereby providing an additional tool for managers tasked with eradication (Hunter, Meigs‐Friend, Ferrante, Smith, & Hart, 2019; Hunter et al., 2015; Kucherenko, Herman, Everham, & Urakawa, 2018; Orzechowski, Ferderick, Dorazio, & Hunter, 2019; Piaggio et al., 2014). However, eDNA analysis has been more equivocal in detecting, semi‐aquatic (Halstead et al., 2017; Rose, Wademan, Weir, Wood, & Todd, 2019) and/or semi‐fossorial snakes (Baker et al., 2018; Crawford, Dreslik, Baker, Phillips, & Peterman, 2020; Ratsch, Kingsbury, & Jordan, 2020). An eDNA assay was also developed for Red Cornsnake, Pantherophis guttatus Linnaeus, 1766, and successfully used for laboratory‐based eDNA accumulation/degradation experiments, but the assay was not tested under field conditions (Kucherenko et al., 2018).…”