I know this picture isn't lovely, but the butterfly decided to rest on a pipe, so that is the photo I took. This is a Satyr Anglewing at UC Botanical Garden in Berkeley on 24 February 2014. I had never seen this butterfly there before.
About a year ago, the creek bed under the bridge was cleared of a mass of vegetation and the stinging nettle had more room to spread out. Since nettle is the larval food plant of this butterfly, I think that more food plant led to more butterflies.
I hope Satyr Anglewing will be a regular at the Bot Garden.