Are you sure that the wings were not moving? The shape and surface area of a
hummingbird’s wing is such that it cannot maintain lift when the wing is not
actively moving. They generate lift on both the downstroke and up stroke. As
the wing moves forward and down, lift is generated (same is true for any other
bird). At the bottom of the downstroke, a hummingbird flips its wing upside
down. (Move your arm down and forward with palm down then rotate your arm to
raise it and bring it back with palm up.) Without the ability to do this a
hummingbird would lose lift and drop slightly between wingbeats, even though
they are flapping at a very rapid rate. So holding the wings still, but
outstretched, would cause a hummingbird to lose altitude very quickly.
I have heard reports of hummingbirds gliding, but usually for only a second or
two and very quickly descending or just for the second or two as it lands. I’ve
not heard reports of any long periods of gliding. Doing so, if only briefly,
would allow a brief period of rest, but a significant lose of altitude. The
bobbing flight of a goldfinch (flap-glide-flap-glide) is a way for them to gain
brief periods of rest while on the wing. In this case, however, the glide is
with wings held against the body
Dan Gleason
---------------
dan-gleason@xxxxxxxxxxx <mailto:dan-gleason@xxxxxxxxxxx>
• Co-owner, Wild Birds Unlimited of Eugene
• Author of "Birds! From the Inside Out" and "Looking for Yellowheads"
• Instructor of Field Ornithology, University of Oregon
541-953-4726
On Jun 27, 2015, at 1:18 PM, kent@xxxxxxxxxxxx <mailto:kent@xxxxxxxxxxxx>
wrote:
I was in my backyard in Southeast Portland the other day and an Anna’s
Hummingbird was making its way around the garden dining on flower nectar.
Occasionally it would fly up to a tree and perch for a moment or two and then
return to the garden. This particular one glided several times for about
10-14 feet as it descended at about a 45 degree angle, it’s wings completely
outstretched and fixed. When it neared flowers it resumed its rapid wingbeat
to hover. I’ve been a fairly avid birder for 40+ years and have never seen
this behavior before.
Has anyone else observed or heard of this before?
-Kent, Portland, OR
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