Activity Patterns of Ornate Box Turtles (Terrapene ornata) in Northwestern Illinois
Activity patterns of ectothermic animals are affected by weather, time of day, and season, but quantifying these effects can be logistically challenging. We used an automated radio telemetry system to quantify Ornate Box Turtle (Terrapene ornata) activity patterns for two years in northern Illinois. Continuously collected activity data were paired with meteorological data collected from the site to determine factors influencing turtle behavior. Temperature, relative humidity, rain, year, month, time of day, and reproductive status affected activity levels. Increased activity levels corresponded with rain events, and males were generally more active than females, especially during spring and late summer. Overall, turtles were less active during an uncharacteristically warm and dry year compared to a year with conditions that were closer to the long-term average. Bimodal daily activity patterns have been reported in more southerly populations, and we found similar patterns near the species’ northern range limit, indicating that thermal constraints may limit activity of this species across its range. Activity comparisons between a year with normal meteorological conditions and an abnormally warm and dry year provide insight to the effect that further onset of climate change may have on the activity of Ornate Box Turtles.
Mean turtle activity and ambient air temperature in spring and summer of 2011 and 2012 in a population of Ornate Box Turtles (Terrapene ornata) in northwestern Illinois.
Mean hourly activity of reproductive females, non-reproductive females, and males from 7 April to 20 September 2011 and 13 March to 24 August 2012. Turtles were generally less active in 2012 during an exceptionally warm and dry year compared to 2011 when conditions were closer to the historical average. Hours in which there was a significant effect of reproductive status on activity are marked with an asterisk.
Mean hourly activity for reproductive females, non-reproductive females, and males from 15 April to 13 September 2011. Males were generally the most active group, especially in spring and early fall. Hours in which there were significant differences in activity between reproductive status groups are marked with asterisks.
Mean hourly activity levels on days with (n = 100) and without (n = 231) rain from May to September in 2011 and 2012. Turtles were generally more active on days when rain occurred. Hours in which there was a significant effect of rain on activity are marked with an asterisk.
Mean hourly activity before and during the 2011 nesting season. High male activity levels before the nesting season may be associated with mate searching. Female activity associated with nesting likely resulted in relatively more female activity during the nesting season. Hours in which there were significant differences in activity between reproductive status groups are labeled with asterisks.
Mean activity levels from noon to noon across nights when at least one female was found to have nested in 2011 (n = 10 nights) and 2012 (n = 5 nights). For each night when nesting occurred, the activity of females who nested on that particular night was compared to males and females that did not nest in that respective year. Increased female activity associated with nesting often began hours before cavity construction and continued well into the following morning. Hours in which there was a significant effect of turtle reproductive status on activity are marked with an asterisk.
Contributor Notes
Associate Editor: J. D. Litzgus.