Orange-crowned Warbler (Leiothlypis celata)

This warbler popped into our garden where it posed for photos. They are a fairly common breeder in much of California, but this one is a different subspecies. It's one of the gray-headed types, either "L. c. orestera" from the Rocky Mountains and Great Basin ranges, or nominate "L. c. celata" from Canada and Alaska. It is often difficult to tell these two apart. That said this individual has a drab yellow-green back and relatively uniformly yellow underparts suggesting it is a female "L. c. orestera." Nominate "celata" has the upperparts more gray-green and underparts marked by gray blotches and streaks. Also "orestera" is regular in California in migration and winter while "celata" is extremely rare. Formerly included in the genus "Vermivora" and "Oreothlypis."