Jason thinks black-chinneds are harder to recognize than Anna's in the same range. He argues, “Structure can be more useful than color.” “The black-chinned has a longer, slightly decurved bill and a thinner body and neck than Anna's and Costa's.”
Jason adds, “Look for a black throat with a thin, deep purple gorget bow tie only visible when the light perfectly reflects to the viewer’s eye.”
Females and immatures of both species have metallic green backs, white undersides, and white outer tail feather ends.
A reader wrote to experts asking why she seldom sees colored males. “I only see female black-chinned hummingbirds here. Where are all the men? says Garden Ridge, Texas resident Marlys Baldwin.
Kenn and Kimberly Kaufman claim black-chinned and other hummingbird males often depart. Because all fledged young birds look like adult females, they outnumber the more colorful males during and after nesting season.
They also like different environments. Females stay at garden level and are easier to notice than males, who sit on treetop twigs to scan for females or competing males.
Hummingbirds don't create pair bonds, therefore a male may leave after mating, leaving the mother to raise her offspring.