[obol] Cattle Egrets

[Jeff Gilligan]

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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