[obol] Fw: Barn Swallow flock on NEXRAD?

[Floyd Schrock]

For those interested in following the story of the roosting BARN SWALLOWS in 
Yamhill Co., here is an interesting message I received from Bruce Cousens of 
the Purple Martin Recovery Team in Nanaimo, BC.  It seems likely that our 
Oregon flock of Swallows is showing up on radar.  Of course, it's not 
confirmed yet, but appears probable.  Anyway, I'm quite certain it's not a 
Purple Marting flock in my neighborhood.

He also forwarded a link to the NEXRAD image, but perhaps I should not 
attach it here.  It looks like this, if you want to try accessing it: 
NEXRAD Portland, OR (RTX) 06-09-05 anim4.gif.

=====================
Floyd Schrock
McMinnville, Oregon  USA
fschrock at macnet.com

----- Original Message ----- 
From: Bruce Cousens & Charlene Lee (PuMa Coord.)
To: stan Kostka lynn Schmidt ; Floyd Schrock
Sent: Tuesday, September 05, 2006 8:47 AM
Subject: Re: Barn Swallow Roost ?


Thanks Stan and Floyd!... Yes, I think there is a good chance this BASW 
roost is what I have been seeing in the radar images.

After a quick check of the area on Google Maps (<www.google.maps.com>), the 
Greenacre Rd. site described is only about 8 mi as the swallow flies from 
the location Char Corkran suggested at Champoeg State Park, and it's 
certainly well within the ~15 mi accuracy of the NEXRAD radar images, so the 
odds of it being anything else seem pretty long. Now we just need some 
ground truthing for confirmation.

As well, the NEXRAD dispersal signature at 6:15-8:00+ am this morning and 
yesterday - a lop-sided expanding circle with most of the visible echo 
spreading roughly east - is much stronger than a week ago and now visible on 
radar for ~2 hrs (see attached .gif animation loop), as one might expect if 
the roost is building to a ~mid-Sept. peak. Interpretation of the base 
reflectivity images is affected by local weather conditions, ground clutter, 
etc., so I will continue to monitor and document the roost signal for 
consistency over the next few days. There are still some small BASW groups 
here in central Vancouver Is. as of yesterday, perhaps family groups with 
late second broods, but most have left their breeding areas now.

A martin roost signature should (in theory) be getting weaker as the numbers 
decrease. However, some martin roost signatures at similar latitudes in the 
northeast US with similar or slightly earlier nesting timing are still quite 
strong, so it's not clear where our birds are at the moment and it may be 
premature to assume they have migrated. In the PNW we really have no idea 
where they go after they leave the colonies, what they do or when they 
actually migrate south, and apart from premigratory roost documentation and 
timing in the east, we don't really know much more about eastern PUMA 
post-breeding behaviour yet either (hence the eastern radiotelemetry 
tracking work and the current search for the mysteriously vanished tagged 
juvenile birds).

Floyd: Any chance there might be a few hundred (or a few thousand) Purple 
Martins hiding in among all the BASW at the roost? The best chance of 
detection might be to listen for them during dawn dispersal at ~6:00-6:30 
am - it's possible different species present have slightly different 
dispersal timing and their calls are quite distinct from those of other 
swallows. PUMA and BASW are often loosely associated at coastal breeding 
locations here and in post-breeding feeding flocks at low altitude, so it 
wouldn't be a surprise to find them in a mixed roost of this sort - in fact 
it's the first place I'd look.

This may be the first reported BASW or mixed swallow roost of anything like 
this size in the PNW to my knowledge (but it's not the species I work with 
most closely, so my knowledge is limited - I wasn't aware BASW gathered in 
such large roosts prior to migration). It's the only such radar signal I've 
found in the PNW or on the west coast so far, though logic suggests there 
should be others, perhaps smaller, and It's well worth documenting more 
thoroughly in my opinion, especially since it seems to occur there annually. 
It's certainly of interest from a natural history and maybe a conservation 
perspective, especially if most/all of the BASW from BC, WA and OR are 
concentrated in that cornfield at some point.  Certainly brings new meaning 
to the popular Field of Dreams phrase about another cornfield: "Build it and 
they will come."

I will keep monitoring the NEXRAD radar roost signature for changes over 
time in the near future, at least as long as the clear weather holds, so we 
can correlate these images with any local observations that would help to 
confirm that it is indeed the BASW roost the radar is detecting, as well as 
track the duration of the roosting period over time. Any on site 
observations anyone wishes to add would be most appreciated and I'll try to 
put everything together in a short article for publication later in the 
year.

I would love to see this BASW roost in person as well as remotely on radar, 
but it's one heck of a commute from Nanaimo, BC... If Floyd or anyone else 
happens to have pictures of it that they could send me, that would be much 
appreciated.

Cheers,    ...Bruce
______________________________________________________
Bruce Cousens, B.Sc., M.Sc., R.P.Bio., Senior Biologist,
BC Purple Martin Stewardship & Recovery Program Coordinator,
Georgia Basin Ecological Assessment and Restoration Society
#133 - 4176A  Departure Bay Rd., Nanaimo, BC, Canada  V9T 4V7
Phone/msg./fax:  (250) 758-2922; E-mail:  pmartins at island.net
______________________________________________________

  ----- Original Message ----- 
  From: stan Kostka lynn Schmidt
  To: Bruce Cousens Charlene Lee

  Sent: Monday, September 04, 2006 2:06 PM
  Subject: Fwd: Barn Swallow Roost ?


  Hi Bruce,


  Here's some info on the Barn Swallow roost in Oregon.   Do you think this 
could be the source of the NEXRAD signature ?


  Stan



  Begin forwarded message:


    From: "Floyd Schrock" <fschrock at macnet.com>
    Date: September 4, 2006 10:33:41 AM PDT
    To: "stan Kostka lynn Schmidt" <lynnandstan at earthlink.net>
    Cc: <pmartins at island.net>
    Subject: Re: Barn Swallow Roost ?




    Hello Stan,
    .
    .
    .
    Here is a copy of my first 2006 report to OBOL on August 23:


    ------------------------------------------
    "I wasn't looking for it, and I wasn't expecting it this early, but this
    evening I happened upon the re-forming, annual congregation of BARN 
SWALLOWS
    going to roost in standing corn near the Willamette River in Yamhill Co. 
If
    the flock grows like I have seen it grow each year for the past 8, it 
will
    get much larger during the coming month, but it was impressive already 
with
    what I estimated between 30,000 and 50,000 individuals.  As usual, I 
could
    hear a few VIOLET-GREENS in the mix.  The earliest I've found the flock
    previously was in mid-September.


    "The location of the roost this evening was in the same general area a 
few
    miles south of Dayton where it is every year. (Greenacre Road off Hwy. 
221,
    straight at the first curve onto Nichols Rd., then down the hill to the
    cornfields in the bottomlands.  P. 59 in DeLorme.)"


    =====================
    Floyd Schrock
    McMinnville, Oregon  USA
    fschrock at macnet.com