Tolerances to environmental temperatures, and reactions to thermal
stimuli influence the behavior of ectothermal animals to a large
extent. _Terrapene ornata_, like other terrestrial reptiles
inhabitating open grassland, is especially subject to the vicissitudes
of environmental temperature. Other species of turtles living in the
same area are more nearly aquatic and therefore live in a microhabitat
that is more stable as regards temperature.
Approximately 500 temperature readings in the field and many others in
the laboratory were obtained from enough individuals to permit
interpretation of reactions involved in basking, in seeking cover, and
in emerging from temporary periods of quiescence at various times of
the day.
Box turtles commonly used open places such as cow paths, ravines, and
wallows, for basking as well as for feeding and as routes of travel.
Burrows, dens beneath rocks, and forms, were used as shelter from high
and low temperatures as well as from predators. Determining whether a
turtle was truly active (moving about freely, feeding, or copulating),
was basking, or was seeking shelter was difficult because the turtle
sometimes reacted to the observer; for instance, basking turtles,
whose body temperatures were still suboptimum, might take cover when
surprised, and truly active turtles might remain motionless and appear
to be basking. By scanning open areas from a distance with binoculars,
an observer frequently could determine what turtles were doing without
disturbing them. In the final analysis of data, temperature records
accompanied by data insufficient to determine correctly the state of
activity of the turtle, were discarded, as were temperature records of
injured turtles and turtles in livetraps.
Cowles and Bogert (1944:275-276) and Woodbury and Hardy (1948:177)
emphasized the influence of soil temperatures on body temperatures. It
is thought that air temperatures played a more important role than
soil temperatures in influencing body temperatures of _T. ornata_.
Soil temperatures were taken in the present study only when the turtle
was in a form, hibernaculum, or den.