[texbirds] Re: Wild speculation of transgulf migration
- From: Clay Taylor <Clay.Taylor@xxxxxxxxxxxxxxxxx>
- To: "Fred_Collins@xxxxxxxx" <Fred_Collins@xxxxxxxx>, "1 Texbirds (texbirds@xxxxxxxxxxxxx)" <texbirds@xxxxxxxxxxxxx>
- Date: Tue, 9 Apr 2013 14:03:51 -0400
Fred -
No, a tail wind is a tail wind - it simply allows them to move across the
ground more quickly. If a bird can only maintain a sustained flight speed
of, say, 40 mph, and the tailwind is at 50mph, it will be flying at 90mph
ground speed, but from the bird's viewpoint it will still be flying forward
through the air around it at a 40mph airspeed. If it tries to turn around
and go INTO the wind, then it has a problem.
Clay Taylor
TOS Life Member
Calallen (Corpus Christi), TX
Clay.taylor@xxxxxxxxxxxxxxxxx
-----Original Message-----
From: texbirds-bounce@xxxxxxxxxxxxx [mailto:texbirds-bounce@xxxxxxxxxxxxx] On
Behalf Of Collins, Fred (Commissioner Pct. 3)
Sent: Tuesday, April 09, 2013 1:51 PM
To: 1 Texbirds (texbirds@xxxxxxxxxxxxx)
Subject: [texbirds] Wild speculation of transgulf migration
John Arvin wrote:
Subject: [texbirds] Monitoring spring bird migration using NEXRAD weather radar
Wow! Winds at 4000 ft. this morning are 52 kts. at Brownsville, 56 (!) at
Corpus, 39 at Lake Charles, and I wasn't able to get a reading from New Orleans
but expect it to be a little less than at Lake Charles. With tailwinds like
that the average small passerine adds its own flight speed and you get up to
near 100 miles per hour for a Gulf crossing. That puts migrants on the northern
Gulf coast quite early in the day. These winds are being sucked up into a deep
low pressure area in the southern Great Plains.
A couple of questions come up: there must be a maximum tail wind speed above
which birds cannot control flight and it becomes dangerous for them, but I have
never seen any data, or even speculation on that. And blizzard conditions are
advertised in association with this Low. Are birds in danger of overshooting
the survivable terrain into which they are headed? I expect the violet weather
associated with the Low would put them down before the blizzard condition set
in but that is just my speculation.
I love to speculate on transgulf flight speed and have often speculated 70-80
miles per hour but 100mph is even more though provoking. In light of the wind
speed data presented I suspect that this is not an all-time high either but
maybe a fairly regular occurrence. It can be windy on the coast and especially
in the Valley. I know there are a few meteorologist that read Texbirds, maybe
they can speculate further.
As for how much tail wind is too much, certainly that pertains to large
aircraft and sailboats but is likely directly linked to mass and aerodynamics.
I suspect that small birds like most passerines and perhaps larger ones like
shorebirds may tolerate tail winds well beyond what may interfere with machine
aircraft. I know that there are also a few physicist that read Texbirds that
may speculate in a more informed matter than I.
Fascinating thought a warbler or hummingbird traveling at 100-120 miles an
hour. That makes the gulf crossing in 5-7 hours. If a Bar-tailed Godwit can fly
for 96 hours can a warbler fly half that long? Maybe flying from South America
to Texas or from Newfoundland to South America is much more plausible than we
can imagine in our earth bound bulking frames and minds.
Fred Collins
(281) 357-5324
Director: Kleb Woods Nature Center
Cypress Top Historical Park Commissioner Steve Radack Harris
County Precinct 3 www.pct3.hctx.net
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