Survey methodology for detecting eastern massasauga rattlesnakes in southern Michigan

Abstract

The U.S. Fish and Wildlife Service listed the eastern massasauga rattlesnake (Sistrurus catenatus catenatus) as threatened in 2016 under the 1973 Endangered Species Act. We tested a visualencounter survey method during 2016 to aid researchers and managers in successfully detecting massasaugas in occupied habitat in southern Michigan, USA. We conducted 54 surveys (paired, independent searchers) in 2-ha areas occupied by telemetered massasaugas. Our detection process parameters included environmental conditions (air temperature, humidity, solar radiation, surface temperature, precipitation) and searcher characteristics (e.g., experience, time spent searching). We detected massasaugas on 11 of 54 surveys. Detection probability from the null model was 0.31; however, we found that time spent searching and minimum air temperature improved detection probability. Detection probability approached 1.00 as time searched by an individual exceeded 90 minutes and approached 0.80 on cooler mornings (12.8°C).Our findings provide survey protocol guidance to increase massasauga detections during visual encounter surveys, which offer useful information to help guide habitat management decisions.

Factors Affecting the Detection of an Imperiled and Cryptic Species

“…The only previous study examining detection in Eastern Massasaugas used 54 search events over two years from May-August paired with radio-equipped snakes [60]. From their 11 detections, they found detection probabilities approached 1.00 when the per searcher effort exceeded 90 min [60], similar to our study.…”

Peer Review #1 of "Using historical dip net data to infer absence of flatwoods salamanders in stochastic environments (v0.1)"

“…comm.). However, if breeding attempts are not highly synchronized across the landscape, if bellwether ponds are unavailable, or if climatic conditions that create "good" breeding years are unknown, the approach can be challenging to implement (Pacifici, Dorazio & Conroy, 2012;Shaffer, Roloff & Campa 2019).…”

“…There has been much attention devoted to detection probability, and especially to the challenges raised when working with rare and cryptic species in stochastic environments (Lebreton et al, 1992;MacKenzie et al, 2002;Royle, Nichols & Kéry, 2005;Pacifici, Dorazio & Conroy, 2012;Kellner and Swihart, 2014;Moore et al, 2014;Specht et al, 2017;Folt et al, 2019). The detectability of many species varies with environmental conditions; annual variation in weather can strongly affect the optimal time of year to survey, and the overall likelihood of detecting the target species (Field, Tyre & Possingham, 2005;Jackson et al, 2006;McConville et al, 2009;Rizzo et al, 2017;Shaffer, Roloff & Campa 2019). If the factors influencing detectability are not known, one can never be confident that failure to detect constitutes a true absence, and the development of standardized monitoring schemes will be severely hampered (Penteriani et al, 2005;Bried & Pellet, 2012;Gervasi et al, 2014;Bellier, Kéry & Schaub, 2016;Crone, 2016).…”

Using historical dip net data to infer absence of flatwoods salamanders in stochastic environments

“…Because regional surveys showed high correlation between reproduction within bellwether ponds and other sites, differences in larval abundance were used to determine whether a year was likely to be appropriate for wide scale sampling (N. Charney, 2020, personal communication). However, if breeding attempts are not highly synchronized across the landscape, if bellwether ponds are unavailable, or if climatic conditions that create “good” breeding years are unknown, the approach can be challenging to implement ( Pacifici, Dorazio & Conroy, 2012 ; Shaffer, Roloff & Campa, 2019 ).…”

“…There has been much attention devoted to detection probability, and especially to the challenges raised when working with rare and cryptic species in stochastic environments ( Lebreton et al, 1992 ; MacKenzie et al, 2002 ; Royle, Nichols & Kéry, 2005 ; Pacifici, Dorazio & Conroy, 2012 ; Kellner & Swihart, 2014 ; Moore et al, 2014 ; Specht et al, 2017 ; Folt et al, 2019 ). The detectability of many species varies with environmental conditions; annual variation in weather can strongly affect the optimal time of year to survey, and the overall likelihood of detecting the target species ( Field, Tyre & Possingham, 2005 ; Jackson et al, 2006 ; McConville et al, 2009 ; Rizzo et al, 2017 ; Shaffer, Roloff & Campa, 2019 ). If the factors influencing detectability are not known, one can never be confident that failure to detect constitutes a true absence, and the development of standardized monitoring schemes will be severely hampered ( Penteriani et al, 2005 ; Bried & Pellet, 2012 ; Gervasi et al, 2014 ; Bellier, Kéry & Schaub, 2016 ; Crone, 2016 ).…”