Colin Carlson

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I am a first semester Honors junior in EEB, and I work with Tobias Landberg on a research project studying the behavior and morphology of the common snapping turtle (Chelydra serpentina), based on footage from a Crittercam project. The footage, collected over the summer, was from three turtles: Jawless and Lafayette from Wethersfield Cove, and Snippy from Shenipsit Lake. (see the snapping turtle research team page for the full story on the turtles). Also, for more information on Crittercam itself, visit National Geographic's Crittercam Homepage.

The purpose of this project is to analyze the behavior of the turtles based on the Crittercam data. This analysis encompasses the breath, dive, pausing, walking, and other aspects of locomotion of the three turtles.

Quantified Behaviors

In all of the analyses, it was important to describe behaviors with a simple terminology. Six basic behaviors can be defined for the purposes of these analyses. The two simplest behaviors are breathing, in which the turtle comes up to breathe, and pausing, in which the turtle does not move. During locomotion, four behaviors can be categorized: vertical swimming (up vs. down), swimming horizontally, and walking along the bottom of the cove or lake.

Breath-Dive Analysis

Fig. 1: Breath duration histograms for the three turtles. From top to bottom, data collected from: Jawless, Lafayette, Snippy. Note that each graph is roughly centered at a different location.
Fig. 2: Dive duration histograms for the three turtles. From top to bottom, data collected from: Jawless, Lafayette, Snippy. Though the difference is slight, this stands in contrast to the breath-duration histograms, as Jawless and Lafayette's plots are both similarly log-normal, although both again differ from Snippy's plot.

The breath and diving behavior of the turtles suggests an influence of habitat on these behaviors. For breath duration (Fig. 1), all turtles were slightly different, yet Jawless and Lafayette were more similar to eachother than to Snippy. This is also true of the distribution of dive durations for the three turtles (Fig. 2). A potential explanation of this difference is based on the depth of the water the turtles were inhabiting during the filming: whereas Jawless and Lafayette are in shallow water and so do not have to swim vertically as much as Snippy (who is in much deeper water), which may reduce the turtles' need to breath longer breaths.

As to the actual relationship between breath and dive, I have found a strong relationship, especially for Snippy. These factors of breath and dive duration ultimately go hand in hand (Fig. 3). I have also statistically tested this fit, and found a strong positive correlation. Note that the order of the breaths is not significant: the fits are equally good for a breath and the preceding dive, and the breath and following dive. These results have been statistically shown to be strongly significant.

Fig. 4: Time Plot, Breath and Dive Duration Over Time for Snippy (Blue Line = Dive Duration; Black Line = Breath Duration)

Locomotion Analysis, Parts 1 and 2: Pausing & Limb Frequency Cycles

The first stage of locomotion analysis in my snapping turtle research was a preliminary analysis of when the turtles paused, and when the turtles were locomoting. This analysis did not include when the turtle was breathing, and did not differentiate between different forms of locomotion. This analysis provided a framework for knowing when the turtles were pausing. However, the major start to analyzing locomotion data came in recording limb frequency cycles for the three turtles. This is currently complete for Jawless and Snippy, and is underway for Lafayette. During continuous bouts of locomotion, the number of limb movements on the right side of the turtle (a logical proxy for the number of limb cycles) is recorded, as is the time duration of the bout. By dividing the movements into duration, a measure of cycles per second for limb cycle frequency is created.

Plotting this over time, there is clearly a negative trend in Jawless's limb cycle frequency. This suggests an escape response, with high initial locomotion rates that decline as the turtle "relaxes," or in more scientific (and accurate) terms, decreases its overall stress level in response to a lack of human intervention and adjustment to the context.

Locomotion Analysis, Part 3: Kinds of Locomotion

Fig. 5: Bar Chart with Intervals for Snippy Locomotion. There is a significant difference between the LCF of horizontal swimming and all the other behaviors, but those other three behaviors are not significantly different.

For these turtles, there are different methods of locomotion that can be differentiated into four behaviors: moving horizontally, swimming up, swimming down, and walking. To monitor limb frequency cycles differing between these behaviors, every bout of locomotion was recorded with the kind of behavior as well as limb cycle frequency. From an ANOVA it appears swimming horizontally for Snippy was significantly slower than swimming vertically (in either direction) and walking (Fig. 5). However, because Jawless is

Current Analyses

Right now, I've finished analyzing breathing rates for all three turtles and a simple analysis of diving vs. pausing, and the data on limb locomotion rates for Jawless and Snippy. I intend to continue this analysis for Lafayette. Ultimately, this is intended to create a full time-scale chart that records the activity of the turtles at any given time, as well as the duration of these events, and for locomotion, the number of limb movements. This data will be analyzed in the hopes of finding trends in the behavior of the turtles.

Labirintus3.jpg Questions or comments can be sent to Colin.Carlson@UConn.edu