Garter snake behavior: Repeatability, habituation, and comparison of life-history ecotypes

Kevin J. Schneider, Eric J. Gangloff, Anne M. Bronikowski Department of Ecology, Evolution, & Organismal Biology, Iowa State University

Methods • Twenty-seven captive born snakes from the two

ecotypes were placed in a neutral test arena and video taped for 60 seconds in repeated trials on consecutive days.

• Snake velocity was retrieved using Ethovision software. Solomon Coder software was used to extract number of tongue flicks, an information-seeking exploratory behavior.

• We used mixed linear models to estimate repeatability, quantified changes in behavior, and determined correlation of exploratory behaviors.

Introduction • Pace-of-Life-Syndrome (POLS) is a hypothesis

proposing that life-history traits, physiology, and behavior will be correlated within individuals in any given population.

• Two ecotypes of the western terrestrial garter snake (Thamnophis elegans) are shown to have different life-histories, with lakeshore populations showing fast paced (L-fast), and the meadow populations displaying a slow paced (M-slow) life-history.

• Gravid females of both T. elegans ecotypes were caught from field sites at or near Eagle Lake, California. These snakes were brought to Iowa State University, giving live birth in 2010. The captive snakes born in 2010 were used in this experiment.

• Life-history traits can covary with behavior and animal habituation, which can impact the survival and long-term health of a population.

Research questions Q1: Are snake behaviors repeatable? Q2: Do garter snakes demonstrate habituation when placed in a behavioral arena? Q3: Will garter snakes of different ecotypes – M-slow and L-fast – differ in exploratory behaviors?

Acknowledgments__ Funding support provided by: National Science Foundation CBiRC Research Experience for Teachers, & Iowa Academy of Science, NSF IOS grant #1558071 Thanks to the ISU RET staff, including Adah Lesham, Stacy Renfro, Craig Walter, Maureen Griffin, and Eric Hall. Additional thanks to Dowling Catholic High School; and to Anne Bronikowski, Kaitlyn Holden, and Eric Teitsworth for providing valuable guidance in the field. A special thanks to Eric Gangloff for truly displaying the heart of a teacher. All work done with permission from the Anne Bronikowski lab, the Iowa State University IACUC, and CA Department of Fish and Wildlife.

Literature Cited Bronikowski, A.M., & Arnold, S.J. 1999. The evolutionary ecology of

life history variation in the garter snake thamnophis elegans. Ecology, 80: 2314-2325.

Reale, D., et al. 2010. Personality and the emergence of the pace-of-life syndrome at the population level. Phil. Trans. R. Soc. B, 365: 4051–4063

Sparkman, A.M., et al. 2014. Physiological indices of stress in wild and captive garter snakes: Correlations, repeatability, and ecological variation. Comparative Biochemistry & Physiology A, 174: 11-17.

Discussion & Conclusions • We found mixed support for the POLS

1) Snakes from the two ecotypes showed no difference in behaviors.

2) A correlation exists between the exploratory behaviors average velocity and tongue flicks.

• T. elegans captive snakes demonstrated habituation to the arena during trial two as indicated by decreased tongue flicks and decreased velocity.

• Correlation showed differences between ecotypes, but sample size was small.

Future Directions • Study differences in snake cognition and

behavior across geographic ranges.

• A similar experiment should include field animals in comparison with captive raised animals to determine the interplay of behavior, genetics, and the environment.

The lead author shows off a large, gravid female garter snake. Similar snakes to the one shown were the mothers of the snakes used in this experiment.

Results

Screenshot of a video recording with a T.elegans captive snake in the test arena. Ethovision software was used to track the snake’s movement by sensing a colored sticker placed on the center of the snake’s head. Note the path of this snake indicated with red line.

Tongue Flicks Avg. Velocity

Repeatability = 0.32

(P = 0.05)

Repeatability = 0.51

(P = 0.004)

Garter snakes demonstrated high conditional repeatability between trials. This means that

individuals were consistent in their behaviors but different from each other.

Both L-fast and M-slow)ecotypes demonstrated decreased velocity and tongue flicks between trials. Data are least-squares

means from a mixed linear model. Error bars are ± SE.

Effect of Trial: P=0.07, Ecotype P=0.91 Effect of Trial: P=0.03, Ecotype P=0.61

L-fast snakes demonstrated a positive correlation between tongue flicks and average velocity. No such correlation is shown for M-slow, and it should be noted that there were only four snakes in the study for that ecotype. Correlation of Tongue-flicks & Average Velocity L-fast: R2 = 0.20, P = 0.0027 M-slow : R2 = 0.023, P = 0.70

A meadow near Eagle Lake, the habitat of M-slow. Habitat characterized by low temps, low predation, and variable water and prey availability.

Eagle lake shore, the habitat of L-fast. Habitat characterized by higher temps, high predation, and consistent water and prey availability.