Re: [SBB] Collared-doves in San Martin

[Joseph Morlan <[[email protected]]>]

On Mon, 2 Oct 2006 22:07:48 -0700, "Steve Rottenborn"
<[[email protected]]> wrote:

> I'm not sure where 
>the new birds are coming from, but such a sudden increase (especially 
>without ECDO showing up in numbers elsewhere in northern Santa Clara County) 
>suggests local releases.

I'm not sure about that.  

It has been suggested that these birds may have an uncanny ability to find
each other, once a few birds settle in.  The entire range expansion has
been characterized by a few birds in a local area followed by sudden
increases in the size of the flock in that area.  Alvaro noted that in a
residential area in Half Moon Bay, and a similar phenomenon occurred at the
Salton Sea, where a small flock multiplied into well over 50 birds in a
relatively short time. 

This is not to say the San Martin ECDO are not from releases, but without
more direct evidence to the contrary their appearance does not seem to be
distinguishable from the modus operandi of the species' current range
expansion. 



-- 
Joseph Morlan, Pacifica, CA 94044   jmorlan (at) ccsf.edu 
Fall Birding Classes start Sept 6   http://fog.ccsf.edu/~jmorlan/
California Bird Records Committee   http://www.wfo-cbrc.org/cbrc/

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