Mourning Cloak (aka Camberwell Beauty in England). The first butterfly for me this year, though Georgia saw the ubiquitous Spring Azure this morning too), it was pretty tattered, suggesting it might be a overwintering adult:
Overwintered adults mate in the spring, the males perching in sunny openings during the afternoon to wait for receptive females. Eggs are laid in groups circling twigs of the host plant. Caterpillars live in a communal web and feed together on young leaves, then pupate and emerge as adults in June or July. After feeding briefly, the adults estivate until fall, when they re-emerge to feed and store energy for hibernation.