When the temperature of the outside air exceeds their internal body temperature, jackrabbits living in hot, arid lands will when the temperature of the outside air exceeds their internal body temperature, jackrabbits living in hot, arid lands will dilate the blood vessels in their large ears to transfer more body heat to the environment. increase motor movements to find a sunny area to maximize heat transfer into their bodies. constrict the blood vessels in their large ears to reduce transfer of external heat to the blood in their ears. begin involuntary shivering of their skeletal muscles in order to generate more metabolic heat. increase pigmentation in their ears, darkening them to maximize their capacity to take up heat?