Isn't science exciting? Just when you think you have it all figured out, someone comes along with a new perspective or new methodology to apply to the data. Thanks to those able correspondents who checked the internet for the source of the Dive Noise in Annas Hummingbird, i.e. its tail feathers. Those who know me as a stubbornly C19th person, will appreciate how I have struggled to come to terms with the C20th, let alone the internet!. At Cooper Ornith. Socy meetings, I've talked to both Stephen M. Russell and the late Luis Baptista about the cause of the dive sound. In his BNA account, Russell says there is spectrographic evidence that the sound is "mostly , if not entirely, vocal in origin" (Baptista and Matsui 1979). But hedging his bets Russell also cites Stiles (1982) that "the noise is too loud in relation to the size of the syrinx and air-sac system to be vocal." So a recent ornithological mystery is solved and my apologies to the Tweets en masse for attempting to pull the wool over your collective ears.
To make myself feel better, I took a two hour late afternoon walk around the open space areas of Discovery Park, noting 17 male Annas Hummingbirds on display territories. As a comparison, on March 6,1983, I counted 24 male Annas on territory, plus one Rufous male and one Annas female. Do not think this reflects an actual decline, more the cold weather and the complete absence of flower bloom in the park except for Indian Plum

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