This is a Mourning Cloak (Nymphalis antiopa) which is another butterfly that you might see fluttering about in the sun on a warm winter day. A butterfly that overwinters as an adult, but enjoys those days when the temperature rises.

Like the few other butterflies that overwinter as adults, the Mourning Cloak finds a crevice in a rock, under a wedge of bark on a tree, or beneath a shingle on a house seeking shelter from the cold, as they go into a state of torpor. These butterflies have chemicals, glycols, in their bodies that work like anti-freeze, which prevent ice crystals from forming. Protection from the freezing cold.

Watch for them when the temperature is much warmer than average. Watch for them on the sunlit side of your house. Watch for them taking a break, stretching their wings, waiting for spring.