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Nesting may begin in December. In the male's courtship display, he hovers in mid-air giving a buzzy song, then flies much higher before diving steeply and rapidly toward the female, making a loud explosive popping sound at the bottom of his dive. He may also buzz back and forth in front of the perched female in short flights. Detailed analyses of male displays revealed that after powering the initial stage of the dive by flapping, males folded their wings by their sides, at which point they reached an average maximum velocity of 385 body lengths. This is the highest length-specific velocity known for any vertebrate. They then spread their wings to pull up and experienced centripetal accelerations nearly nine times greater than gravitational acceleration. This acceleration is the highest reported for any vertebrate undergoing a voluntary aerial maneuver, with the exception of jet fighter pilots. Displaying Anna's Hummingbird males produce both a vocal song and a dive-sound (made with the wings and outermost tail feathers) that sounds similar to a portion of the song, an intriguing observation discussed by Clark and Feo (2010).
The nest of an Anna's Hummingbird, which is relatively large for a hummingbird nest, is usually constructed on a branch of a tree or shrub, but may also be in vines, on wires, or under eaves. It is typically 1 to 8 m above the ground. Built by the female alone,it is a cup of plant fibers and spider webs. It is lined with fine plant down (and sometimes feathers) and the outside is camouflaged with lichens. The female may continue building after eggs are laid. The female incubates the 2 (rarely 1 or 3) white eggs by herself for 14 to 19 days. The young are fed by the female and take their first flight at around 18 to 23 days.
Anna's Hummingbird is very common over much of its range and has adapted well to suburban areas.
(Kaufman 1996; AOU 1998; Clark 2009; Clark and Feo 2010)