1. I hear about experiments wherein humans can raise/lower digital body temperature at will with biofeedback (these were mostly what came up in my search, but in terms which were less than helpful to me). Can anyone tell me what it actually feels like to do this? Is it like one is 'willing' the temperature to change, concentrating on the digit, or what? Does it change the appearance of the digit at all? Does anyone know what is actually physically happening when this occurs? (Where does the heat come from? The bloodstream? If so, where does it enter the bloodstream? Is the temperature change just on the surface or a thin layer of skin or the whole digit?) Also: If the temperature is raised as a panic response or such, and thus is less controlled, is it likely to begin or be concentrated in one area? If so, where - the core of the body? One of the POV characters is a member of this race, so the way it feels to raise/lower one's own body temperature is particularly important.
2. The race has large, batlike wings; it seems to me that spreading out the wings could be used to help cool down, especially if the heat is actually carried in the bloodstream. There may be animals which do things similar to this already; I know that at least one sail-backed species of dinosaur is theorized to have used such a mechanism to maintain body temperature. Anything else I should know about this idea?
3. Beyond the fact that this race is uncomfortable being cold and burns a lot of calories when heating up, thus requiring more food than similar races without the ability, are there other things they should do differently?
I have searched variations of 'voluntarily raise temperature' and 'voluntary change body temperature', etc.