Anna's hummingbird (Calypte anna), a medium-sized hummingbird native to the west coast of North America, was named after Anna Masséna, Duchess of Rivoli.
Anna's hummingbird is 3.9 to 4.3 in (9.9 to 10.9 cm) long. It has an iridescent bronze-green back, a pale grey chest and belly, and green flanks. Its bill is long, straight, and slender. The adult male has an iridescent crimson-red derived from magenta to a reddish-pink crown and gorget, which can look dull brown or gray without direct sunlight and a dark, slightly forked tail. Females also have iridescent red gorgets, though they are usually smaller and less brilliant than the males'. Anna's is the only North American hummingbird species with a red crown.
Anna's hummingbirds can shake their bodies 55 times per second to shed rain while in flight, or in dry weather, to remove pollen or dirt from feathers. Each twist lasts four-hundredths of a second and applies 34 times the force of gravity on the bird's head.
The males also use the dive display to drive away rivals or intruders of other species. When a female flies onto a male's territory, he rises up about 130 ft (40 m) before diving over the recipient. As he approaches the bottom of the dive, the male reaches an average speed of 27 m/s (89 ft/s), which is 385 body lengths per second. At the bottom of the dive, the male travels 23 m/s (51 mph), and produces a loud sound described by some as an "explosive squeak" with his outer tail-feathers.
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