This is an uncommon but regular Fall migrant. Most of the California individuals are juveniles such as this. This is a long distance migrant wintering in high lakes in the Andes of South America. Adults are already on their wintering grounds by now, apparently flying most of the way non-stop. The juveniles take longer, and must navigate to their winter home without guidance from their parents. The long primaries project well beyond the folded tertials giving a long-winged effect. Long-distance migrants often evolve longer wings to aid in migration, and this species is a classic example of that adaptation.
Digiscoped with Panasonic DMC-LZ5 | Nikon FieldScope III | 30XWA | hand-held (no adapter)