October 2002 Mystery Bird

This hummingbird was photographed 29 August 1987 in Northern California.

I inflicted this image on the bird identification panel at the recent Western Field Ornithologists meeting in Costa Mesa. The experts agreed that it was a species of Calypte noting that Archilochus hummingbirds would not be exhibiting wing molt as early as August. Also the inner primaries appear square-tipped and relatively broad unlike Archilochus where the feathers are noticeably narrower. Most members were leaning towards Costa's and thought it was an immature male. The short bill and large appearing head were mentioned as supporting features.

However, this photo was taken at Coyote Creek Riparian Station in Alviso, SCL where Costa's would be accidental at best. I don't think the species has ever been positively recorded there. The photographer identified the bird as an Anna's Hummingbird at the time. I believe most immature male Costa's should show a more pronounced white patch behind and below the eye than seen here. The short bill could be an illusion if the head is turned away slightly. The best way to tell for sure would be the vocalizations. Those of Costa's have a bushtit-like quality, quite different from Anna's.

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Photo © 1987 Peter LaTourrette
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