>This is partly due to their metabolic rate, which is much lower in cold temperatures than it is in higher temperatures.

Are you sure this is accurate?

A lower metabolic rate would mean that the animal is generating less heat. Which presumably would confer lower cold tolerance than a high metabolic rate.

Hibernating animals do have a lower metabolic rate. But they compensate with more insulating fur, and by selecting sheltered places to hibernate. The lowered metabolism doesn’t help avoid frostbite.