Allen's

Common name: Allen's Hummingbird
Scientific name: Selasphorus sasin
Clades: Mellisugini - Bees

Allen's Hummingbirds are among the smallest birds, they are only 7.5 to 9 cm (3-3.5 in.) long and typically weigh a little over 3 grams (0.1 oz.).

Extremely similar to widespread Rufous Hummingbird; identical in plumage except for males' solid green back (which can be shown by Rufous too.) Breeds only along a narrow strip of coastal California and southern Oregon. See also: Rufous Hummingbird. On females and immature males, the only way to separate them from Rufous is by the shape of the tail feathers, which is extremely difficult to determine without good photographs.
Identification by eBird & Merlin

2 subspecies:

1. S. s. sasin
   Distribution Breeds from extreme sw. Oregon to s. California; winters in sw. Mexico

2. S. s. sedentarius
   Distribution Largely resident on the Channel Is. and on the nearby mainland of California, from the Palos Verdes Peninsula south through Orange County; post-breeding birds have been collected in Santa Monica Mts., 65 km from breeding grounds on in Palos Verdes (Stiles 1972), and birds that breed on San Miguel I. may winter on neighboring Santa Rosa I., an island that supports groves of introduced winter-blooming eucalyptus (Jones and Collins in press).