chuck: is what you are talking about different from the low frequency wing "buzz" of any close hummingbird? In the same way the Rufous has a cicada-like "whine" associated with it's wings in addition to the "buzz" when it flies close?
chuck may be right that there isn't any pitch shift but it's just an amplitude change (part of the "light sabre" sound effect from "Star Wars" is both a pitch and amplitude change).
Recordings might illustrate the point or we might be just talking at crossed purposes about different sounds. :-)
At 0:55 into this recording from the Maculay there is a nice sample of wing noise with a nice behavior description too. Is the "light sabre" sound associated with backing up/direction change and tail flicking?
http://macaulaylibrary.org/audio/6121/calypte-anna-annas-hummingbird-united-states-california-david-allen
Is this what you are referring to Leah?
Does it sound like the noise you are talking about Chuck?
Ever curious,
Kevin
On Dec 15, 2012, at 7:09 PM, <creinsch at humbirds.org> <creinsch at humbirds.org> wrote:
> Kevin:
>
> It could be that I misunderstood what exactly the sound was that Leah and her son were hearing. I don't know what a "light sabre" sounds like so we may be talking about entirely different sounds, but we definitely hear low frequency wing noise during late molt. I believe the sound we are hearing is not related to Doppler shift, as it is constant in pitch whatever the bird's distance and velocity. Only the volume changes as it moves closer, passes, and moves away.
>
> I'll have to pay more attention to hear what you are describing.
>
> chuck reinsch
> magnolia, seattle, wa
> creinsch at humbirds.org
>
> ----- Original Message ----- From: "Kevin Purcell" <kevinpurcell at pobox.com>
> To: "Leah Wegener" <dlwegener at msn.com>
> Cc: "Kevin Purcell" <kevinpurcell at pobox.com>; "Tweeters" <tweeters at u.washington.edu>
> Sent: Saturday, December 15, 2012 12:27 PM
> Subject: Re: [Tweeters] Hummingbird wing noise question
>
>
> Some thoughts and observations.
>
> I think it's just the "fundamental" from the wing motion throwing vortexes off the wings.
>
> There are two vortexes shed per wing per beat in hummingbirds, one on the upstroke and one on the downstroke as the wings move in figure 8 in "hover mode" flight. That "powered upstroke" is a clever optimization for hovering.
>
> It's a low frequency sound and the vortexes only maintain the structure over a short distance so you have to be quite close to hear it. I've found sitting in a garden amongst flowers is good. I do it in the Thomas St P-patch and get close "listens" when reading when the resident Anne's appears.
>
> If it is generated solely by wing motion it's not gender specific but the frequency might be (different wing lengths; different body weights). I suspect an observational bias in observing only a male on his territory might give that impression. :-)
> I doubt it has anything to do with molt as I hear it every time the same hummer gets close to me over a period of months.
>
> Initially I though the "light saber" effect is Doppler shift from motion. But on thinking about it that would only shift the pitch a small amount at reasonable speeds (~1% at 3 meters per second). I wonder if it's a change in flight style or power that directly changes the wingbeat frequency as the bird moves from a hover to hover + directional flight. If it's the latter you would expect the pitch to increase as it moves away from you (the opposite of the Doppler effect).
>
> Seems like an area of research waiting to be done. Perhaps by a birder with one or more mics at a humming bird feeder connected to a computer to record sound with a video camera or human with a notebook to note behavior and location. With a high speed camera one could see the changes in beat frequency and match them to changes in the sound.
>
> On Dec 13, 2012, at 5:23 PM, Leah Wegener wrote:
>
>> Hi, Tweets,
>> Is it true that only male hummingbirds make the VW engine noise with their wings, the noise that sounds kind of like a light saber? My son observed this in our yard but we cannot find any information that backs this up. I'm not thinking of the mating flight swoop, but just the everyday flying.
>
> --
> Kevin Purcell (Capitol Hill, Seattle, WA)
> kevinpurcell at pobox.com | at kevinpurcell
> http://kevinpurcell.tumblr.com
> http://flickr.com/photos/kevin_g_purcell
>
>
>
>
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--
Kevin Purcell (Capitol Hill, Seattle, WA)
kevinpurcell at pobox.com | at kevinpurcell
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