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A Record Number of Species at a Northerly Location

Hummingbird Diversity

Rich Stallcup

On October 3, 2011, PRBO friend and wildlife artist Keith Hansen identified a young male Costa’s Hummingbird at his gallery in Bolinas, and it stayed around for six days. This was the eighth species Keith has documented there. It was the eighth hummingbird species!
Keith Hansen illustrated the 15 hummingbird species that nest in the U.S. For a key to identifying them, see drawing below.

Hummingbirds evolved in the American tropics, and about 320 species are now known. Only eight regularly occur well north of the Mexican border. (About nine more have been recorded in southeastern Arizona).

Here along the coast of California, Anna’s, Allen’s and Rufous are the only familiar hummingbirds to casual observers, but to that short list Keith has added Black-chinned (8 individuals), Calliope (1), Costa’s (1), Broad-tailed (2), and Ruby-throated (3)! This diversity is certainly the record at any such northerly latitude.

Because most of the rare kinds were youngsters—and thus notorious look-alikes—I asked Keith how he was able to clinch each identification. Was it after studying museum specimens? With the counsel of knowledgeable friends? Vocalizations? A glint of some feather color? Or perhaps the recent publication of two field guides dedicated to Trochilidae (the hummingbird family) of the United States?
Adult male hummingbirds, such as Costa’s (left) and Allen’s, are much easier to identify than juveniles and females.Photos by Peter LaTourrette (left) and Rich Stallcup.

His answers: “There are actually four reasons why I get so many of these rare birds at the gallery. One is the location: my gallery sits just one hillside away from the coast, and southbound migrant hummingbirds tend to group up along the coast. So I get large numbers of them coming to the nearby oaks, conifers, ornamentals, and a lot of flowers.

“Second is the number of hummingbird feeders. I can see all the feeders out my window, and so can the birds, which are territorial—up to a point. Fewer than four feeders here would attract only one or two hummingbirds, so I have eight, which can attract unlimited numbers: there have been as many as 50 hummingbirds here at one time.(See note below about feeding hummingbirds.)
Hummingbird species illustrated above: (a) Anna’s (b) Ruby-throated (c) Calliope (d) Allen’s (e) Buff-bellied (f) White-eared (g) Lucifer’s (h) Broad-billed (i) Violet-crowned (j) Black-chinned (k) Costa’s (l) Rufous (m) Blue-throated (n) Magnificent (o) Broad-tailed

“Then there’s the situation at my gallery. From inside, I can see out onto patio, and when anything unusual shows up, I’m able to videotape it through my telescope. Finally, because I have videotape and because there are so many expert birders in this part of the world, I’m able to get all the information I need as far as identification is concerned.

“I would say that Sheri Williamson’s and Steve Howell’s recent books (see note below) on hummingbirds have been the single biggest boon to me as far as identifying immature and females and odd-plumaged hummingbirds.”

Over time and many birding miles traveled, some of us have identified young of all eight species Keith has seen in Bolinas. In the nearby region, most of rare hummingbirds occur in the fall on Marin’s outer coast, but because those migrants are so blazingly fast and elusive, documentation is scarce. As more birders learn the subtle characters that are unique (primary feather formulas and shapes; bill dimensions and face patterns; posture and behavior), our understanding of the true status and distribution of these tiny gems is certain to change.

Learn how to feed hummingbirds responsibly in “An American Dream” by Rich Stallcup—Focus 30, winter 1991–92, found online at Books referred to in this article: Hummingbirds of North America: Peterson Field Guides, by Sheri Williamson, Houghton Mifflin Company, 2001; and Hummingbirds of North America: A Photographic Guide, by Steve N.G. Howell. Princeton University Press, 2003.