FW: [obol] Cattle Egrets

[Jeff Gilligan]

Apparently the number of Cattle Egrets in California is not the explanation
for the species' decline as a fall/winter dispersant to the Oregon coast.
Jeff 


-
Nick,

The Cattle Egret is by far the commonest heron in the Imperial Valley,
with
rookeries containing thousands of nests.  I have never attempted to
determine just how many Cattle Egrets are present, nor have I ever seen
the
results of Cattle Egret surveys from the area if such have ever been
conducted, but would not be surprised if the area supports 100,000 or
more
Cattle Egrets.  I have not noticed any recent decline in numbers.

Sorry that I am unable to provide more accurate information.

Guy McCaskie
Secretary, CBRC
PO Box 275
Imperial Beach, CA  91933

----- Original Message -----
From: "Lethaby, Nick" <nlethaby at ti.com>
To: "Guy McCaskie" <guymcc at pacbell.net>
Sent: Friday, November 03, 2006 9:53 AM
Subject: FW: [obol] Cattle Egrets


Guy:

Can you comment on the trends of the Cattle Egret populations in
Imperial Valley? I assume this is the nearest source of birds for the
rest of the W. coast. Central California coast (Santa Cruz, Santa
Barbara) has had the same decline in late fall/winter Cattle Egrets to
my knowledge.

Nick Lethaby
DSP/BIOS Product Manager
Software Development Systems
Texas Instruments
805 562 5106
nlethaby at ti.com

-----Original Message-----
From: Jeff Gilligan [mailto:jeffgill at teleport.com]
Sent: Thursday, November 02, 2006 9:19 PM
To: Owen Schmidt; OBOL; Alan Contreras
Subject: Re: [obol] Cattle Egrets

I agree with Alan's comments.  Here is my theory as to why Cattle Egrets
have become so rare as a fall through early winter dispersant.

Theory only:  The species only reached the western USA in numbers in the
1970s.  It had progressed across North America from when it had become
established in Florida.  The pioneering birds for this range expansion
were
the fall dispersants.  Where they were able to survive the winter they
established new breeding populations, from which dispersants further
advanced the species' range.  The dispersants to Oregon couldn't survive
the
winters, and eventually the then rather stagnant populations from where
they
came lost the northwest dispersal gene, since it wasn't successful in
advancing the species.

OK - I admit I know nothing about genetics... so comments?

Jeff Gilligan


On 11/2/06 9:09 PM, "Jeff Gilligan" <jeffgill at teleport.com> wrote:

>
> ------ Forwarded Message
> From: Alan Contreras <acontrer at mindspring.com>
> Reply-To: Alan Contreras <acontrer at mindspring.com>
> Date: Thu, 2 Nov 2006 15:10:52 -0800 (GMT-08:00)
> To: Ray Korpi <rkorpi at hotmail.com>, <obol at lists.oregonstate.edu>
> Subject: Re: [obol] Cattle Egrets
>
> In the 1970s and 1980s, Cattle Egret was a much more regular late
> fall-December dispersant on the coast and occasionally inland,
sometimes in
> small flocks.  It was even a semi-regular CBC bird that one hoped to
find.
> Since the early 1990s they seem to have fallen off the map.  I am not
sure
> why.
>
> -----Original Message-----
>> From: Ray Korpi <rkorpi at hotmail.com>
>> Sent: Nov 2, 2006 2:35 PM
>> To: obol at lists.oregonstate.edu
>> Subject: [obol] Cattle Egrets
>>
>> All,
>> What is interesting about my personal Cattle Egret sightings in
Oregon (a
>> limited sampling to say the least) is that two of the three were at
this
>> time of year or later--an October sighting some 10 years ago in
Lincoln Co.,
>> and a CBC sighting at Scappoose Bottoms in Columbia Co.  The only
"breeding
>> season" sighting was a sighting near Burns the first year of the BBA,
which
>> I think is one of a few records for the project.  There may be some
post
>> breeding dispersal ongoing here
>> Ray Korpi
>> rkorpi at hotmail.com
>> Vancouver WA
>>
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>
>
> Alan Contreras - Eugene, Oregon
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