Great explanation Will.The adaptation you are suggesting is more behavioral than physiological. They will learn how to seek out and use refugia that is less impacted by cold. Some physical traits like color may be linked to the behavioral selection.
This is sorta what happens with many species, their adaptation is lead by choices living individuals make, that are adopted by offspring by chance or behavioral selection. Strong selection based on aberrant physiology is more rare. First you need the aberrant physical attribute to exists at the right time.
Less random are many individuals seeking their own best way to cope. Those that select a best coping mechanism survive and carry forward whatever that mechanism is, along with associated physiological traits.
One great example relates to how beavers became nocturnal. Early natural history writers refer to beavers as day time animals, sleeping at night. But people hunted all the ones they could see, so those few with the aberrant habit of being nighttime beavers persisted better.
There are no doubt some of the animals out there in the glades that are also more cold tolerant too.