Open Access Honors Program Thesis
Jeff Tamplin, Professor, Honors Thesis Advisor, Department of Biology
James W. Demastes, Professor, Thesis Committee, Department of Biology
Iowa wood turtles (Glyptemys insculpta) were tracked using radio telemetry to compare juvenile, male, and female habitat usage during specific seasonal activity periods. Field data collected included: time, geographic location, habitat type, surrounding vegetation type and abundance, ambient weather conditions, turtle body temperature and mass, water depth (when aquatic), distance from water, behavior category, and amount of exposure to UV light. While active in 2017 – 2019, the wood turtle population at three Iowa sites was 53% terrestrial and 47% aquatic, with the most frequent respective habitats being emergent clearings (grasses, forbs, saplings) and lotic (river, stream, creek). Females were more terrestrial during the active seasons (44% aquatic), but males were more aquatic (54%). In the Prenesting period, both were mostly aquatic, but males were more so than females (59% versus 52%). Both sexes were overwhelmingly terrestrial during the Nesting period (males: 87%, females: 74%). During the Postnesting period, both largely selected terrestrial habitats, though females did so more than males (75% versus 58%). During the Prehibernation period, both were mostly aquatic (males: 78%, females: 81%). Overall, juveniles were more aquatic than terrestrial (52% aquatic), resembling the behavior of males. In congruence with other wood turtle populations, Iowa wood turtle habitat selection patterns included seasonal and sex-related trends in proximity to water and the usage of specific habitats during active periods (likely associated with shifting thermoregulatory behaviors). Distance from water and terrestrial habitat usage increased during the summer months for both males and females, as ambient temperatures rise, and decrease throughout autumn. Females venture significantly further inland than males during every active period. Due to the stability of water temperatures relative to cool nighttime air temperatures during Prenesting and Prehibernation, the turtles selected aquatic habitats more frequently, and they remained in riparian areas when terrestrial, which have opportune sites for basking while facilitating stream access. Females have a greater affinity than males do for open-canopy habitats during Prenesting. This trend is not only possibly related to egg production, but also to male behavior, which IV involves males using the river to search for mates, socialize and establish dominance. Any differences in overwintering locations do not seem to be sex related. Lastly, further studies should be conducted with larger samples of juveniles.
Year of Submission
Department of Biology
University Honors Designation
A thesis submitted in partial fulfillment of the requirements for the designation University Honors
1 PDF file (x, 30 pages)
©2020 Amanda Stewart
Stewart, Amanda, "Seasonal habitat usage of Iowa wood turtles (Glyptemys insculpta)" (2020). Honors Program Theses. 438.