[EBB Sightings] New info on Anna's

Apologies for this off-EBB-topic post, but it is good to know that  
the mechanical origin of the male Anna's Hummingbird's dive noise has  
finally been proven.  Modern researchers may have overlooked an early  
demonstration of this mechanical origin, though.  At a meeting of the  
Cooper Club (now called the Cooper Ornithological Society) in Fresno  
in April 1938, Thomas Rodgers attached a male Anna's Hummingbird's  
outer tail feather to a slender strip of bamboo. By whipping this  
through the air, he produced a sound nearly identical to the dive noise.

Many years later, Baptista and Matsui (1979) analyzed spectrograms of  
the sound and argued that it is ?mostly, if not entirely, vocal in  
origin.?  Stiles (1982) disagreed with their interpretation,  
suggesting the noise was too loud in relation to the size of the  
bird?s syrinx and respiratory system to be vocal.  Neither Baptista  
and Matsui (1979) nor Stiles (1982) mentioned the early, though  
anecdotal, evidence for a mechanical origin demonstrated by Rodgers  
(1938).  And now, finally, 25 years later, Clark and Feo (2007)  
provide solid evidence to support that notion.

Jeff Davis
Prather, CA

On Sep 9, 2007, at 11:42 PM, Verne Nelson wrote:

> From: SCIENCE NEWS. Week of Aug. 25, 2007; Vol. 172,
> No. 8
> Tail singers Susan Milius
>  The sound effects of Anna's hummingbirds, widespread
> along the West Coast, have been misunderstood,
> according to a new test. A male Anna's hummingbird can
> make sounds with its tail. Some of the males' most
> dramatic noises aren't vocalizations, as has been
> thought. Instead, the birds make noises by whipping
> their tails through the air. Males, with iridescent,
> rose-colored throats and heads, perform aerial dives
> when courting a female or confronting another male.
> For a display, a male flies high in the air and then
> drops nearly straight down. When he's plummeted to the
> level of his intended audience, he pulls out of the
> dive while sounding an explosive squeak. In the late
> 1970s, ornithologists decided that those notes came
> from the birds' vocal organs. Chris Clark and Teresa
> Feo of the University of California, Berkeley have
> challenged that idea by removing some birds' outer
> tail feathers. A clipped male still dives, but he no
> longer makes the sound as he bottoms out. Clark also
> tested the tail feathers in a wind tunnel and was able
> to make noises like the birds'. The researchers
> reported their findings at the July 21?25 meeting of
> the Animal Behavior Society in Burlington, Vt.
> Ornithologists have documented a wide variety of
> noises made by bird wings, from cricketlike rubbing
> sounds to aerial whistles. A tail-feather sound
> effect, though, is quite rare, says Clark.