Date of Award
Spring 4-9-2026
Document Type
Thesis
Degree Name
Master of Biological Science (MBioSci)
Department
Biology
First Advisor
Dr. Dominic DeSantis
Second Advisor
Dr. Al Mead
Third Advisor
Dr. Matthew Milnes
Abstract
The presence of a human observer can influence the behaviour of free-ranging animals, but there are prominent gaps in this knowledge for secretive and small-bodied species. Responses might be cryptic or delayed, and therefore not easily detected using standard methods that facilitate repeated field observations. We used a combination of radio telemetry and accelerometery to assess the potential impacts of regular field observation on the movement behaviour of Timber Rattlesnakes (Crotalus horridus). In this study we found partial support for our hypothesis that human observers would be perceived as a potential threat, and that rattlesnakes would elevate activity and movement duration in response to field observations. During the foraging behavioural season, daily activity intensity and movement duration were positively associated with tracking days (relative to non-tracking days) regardless of sex, body temperature, or behavioural state during observation. This association might be indicative of a flight response to perceived failure of crypsis when natural threat encounter frequencies are low and threat sensitivity is high. This association was not maintained during the mating behavioural season, when reproductive behaviour likely carries increased threat encounter frequencies and possible reductions in threat sensitivity to enhance mate searching success. Activity intensity and movement duration also increased on tracking days with closer approach distances, indicating that rattlesnakes might adjust the intensity of their threat response relative to the perceived risk level of each encounter. We found no significant variation in activity or movement duration in the hour before or after radio telemetry observation, indicating that the above-described responses are delayed for at least one hour after observation. We make general recommendations for improved field study of vipers using radio telemetry, while acknowledging limitations in our datasets and calling for additional systematic research into the potential observer effects on the behaviour of wild-ranging snakes.
Recommended Citation
Price, Ozzy, "Effects of field observation on the movement behaviour of secretive species: a biologging case study with Timber Rattlesnakes (Crotalus horridus)" (2026). Biology Theses. 48.
https://kb.gcsu.edu/biology/48