The following exercpt from an article entitled "Feathered Gems"
by the late Luis Baptista suggests that the "ping" or "pop" sound is
at least partly vocal.
--oryoki
http://www.calacademy.org/calwild/2001fall/stories/hummers.html
"The Costa's hummingbird (Calypte costae) and Anna's hummingbird of
California have very elaborate dive displays during which whistles
(Costa's) or loud pops (Anna's) are produced. It was long thought that
these sounds were produced by the specialized tail feathers, as they
are in the wing feathers of the broad-tailed.
During spring 1977, my ornithology class and I watched a Costa's
hummingbird perform its dive display in the Anza Borrego Desert of
California. At the bottom of its dive we heard a long, drawn-out,
high-pitched whistling sound. I informed my students that this sound
was produced with the tail. At this point, the Costa's perched not
three meters from us, and out of his mouth emanated a shorter version
of the same high-pitched whistle. He clearly had not read the
literature; he wasn't supposed to do that! I then compared
spectrograms of dive-pops of the related Anna's hummingbird and found
that one of the syllables in the song was almost identical in
structure to its "dive-pop" sound. Since then, three independent
observers have reported to me their observations of Anna's
hummingbirds resting on perches and uttering dive-pop sounds. The dive
sounds were vocal after all, and not mechanically produced. "
________________________________________________________________________
________________________________________________________________________
|