[texbirds-freelists] [texbirds] NEXRAD radar observations of migrating birds in the western Gulf coast region; 4/24
- From: John Arvin <jarvin@xxxxxxxx>
- To: texbirds@xxxxxxxxxxxxxxxxxx
- Date: Tue, 24 Apr 2012 15:34:31 -0500
The winds are backing around to the south as the high pressure center that
has dominated these past few days moves eastward. Brownsville and Corpus
are both reporting S winds at ~15 kt. Houston of course is unknowable since
their upper air soundings are not posted to the internet. Lake Charles and
New Orleans are still N but low (7 and 10 respectively). I waited until
late afternoon at High Island hoping for a delayed arrival but to no avail.
Only the "mulberry birds" (tanagers, grosbeaks, catbirds, and thrushes)
that tend to hang around recharging for a week or so before moving on. A
single warbler individual. Meanwhile observers on the lower Texas coast
reported an excellent day. I did not check the upper winds yesterday but I
suspect the return flow had already begun there.
(Later) The VAD wind profiles do indeed indicate that winds since the 7:00
a.m. sounding have turned south or SW at all locations. Brownsville and
Corpus are receiving significant trans-Gulf migrants and the other three
stations small numbers. Whether these birds are landing in coastal woodlots
is another question. I see no indication that they are, but you have to
realize that when they do they disappear from the radar image, so it is a
tough call. The south winds are forecast to increase over the next several
days. Likely most migrants will move on inland before landing until a
significant weather event occurs to stop them on the coast (except for the
daily drop-in by less fit individuals which need to take advantage of the
first opportunity to get on the ground.). I don't see such a weather
phenomenon on the near horizon.
John C. Arvin
Research Associate
Gulf Coast Bird Observatory
103 West Hwy 332
Lake Jackson, TX 77566
jarvin@xxxxxxxx
www.gcbo.org
Austin, Texas
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