Snakes Move in Mysterious Ways: Daily Activity Patterns and Movements of Northern Mexican Gartersnak

Sprague, Tiffany A.

Bateman, Heather L.

College of Integrative Sciences and Arts

Arizona State University

Tempe, AZ 85281 USA

Nowak, Erika M.

Department of Biological Sciences

Northern Arizona University

Flagstaff, AZ 86011 USA

Knowledge of daily activity periods and movement patterns are important components of species conservation and study design. The Northern Mexican Gartersnake (Thamnophis eques megalops) was listed as threatened under the Endangered Species Act in 2014. This species can be difficult to locate and monitor due to its cryptic behavior and selection of complex habitats. Our objectives were to document daily activity and movement patterns of this species and to determine influence of monitoring frequency on daily movement estimates and habitat selection. We located snakes with radio-transmitters every three hours during 24-hour periods and recorded location, distance moved, and macrohabitat type. From June 2015 - July 2016, we monitored 20 snakes during 49 sampling sessions. Snakes were more active and moved longer distances from 9:00-15:00, although some nocturnal activity was observed. Snakes also moved longer distances during the active season (March-October), but short-distance movements were common during the inactive season (November-February). Estimates of daily distances traveled decreased with less-frequent monitoring; a sampling interval of once every 24 hours yielded only 53-62% of known daily distances moved during the active season. These results can help inform management activities and research study design. Managers and researchers should carefully assess timing and frequency of activities in order to meet project objectives.