Survey methodology for detecting eastern massasauga rattlesnakes in southern Michigan

Abstract

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 visual‐encounter 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. © 2019 The Wildlife Society.

Keywords

• detection probability
• eastern massasauga rattlesnake
• Michigan
• Sistrurus catenatus catenatus
• survey methods