Abstract
The effectiveness of thermoregulatory postures in the black dragon (Hagenius brevistylus Selys; Odonata) was tested relative to wind speed and air temperature on live and dead dragonflies in a closed circuit wind tunnel. The postures appeared to allow the dragonflies to behaviorally select body temperatures exceeding a range of 20 C and reach temperatures as low as the ambient air or as high as the sun-warmed substrate. At least one posture appeared to be transitory and appeared to be used primarily to warm up from low body temperatures. Live dragonflies kept individually in a large flight cage showed different patterns of posturing depending on the amount of insolation. Free-ranging dragonflies were not active at low air temperatures, and postured differently in response to different substrate temperatures. We concluded that black dragons can select from a broad range of potential body temperatures as the result of behavioral posturing.
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