Scott Ray wrote that cormorants are as likely to be seen spreading wings
during cold and warm conditions and wondered whether this refutes the
thermoregulation hypothesis.
I imagine air temperature isn't the only variable, but that presence or
absence of sun and amount of wind would both be important. thus
thermoregulation could be an important function over a range of temps.
Remember, a cormorant at 100 degrees body temp (more or less) is always
potentially losing heat to the air, and whether the feathers were wet or
dry would also contribute a variable.