Solitary Vireo, Lily Pond, GGP
This bird was found by Rudy Wallen two days ago. In overall plumage it seems in the overlap zone between an HY female Blue-headed Vireo and an adult male Cassin's Vireo - perhaps an HY male Cassin's could also be in the mix but it seems a bit bright for this. Still having trouble ageing it based on photos, and better shots of the rectrices would help with age and potentially a final ID call.
This morning it was being fairly cooperative at 9 am, just as the sun was hitting the trees around the pond. This pond is near the intersection of Nancy Pelosi and Bowling Green, 75 or so yards up NP toward California Academy of Sciences, on the right. The pond is just in from the road and the bird favors the willow overhanging the pond on the other side of the trail. It has also been seen in the oak overhanging the trailhead and in other trees around the pond.