Re: More Ravens & Grackle


Brad Schram
 

interesting. I was on Catalina Island for a week recently where
Ravens
are residents and Crows are a rare vagrant.
The, essentially correct, wisdom that California's Ravens are more birds of
mountains and drier climes, while Crows are more urban and devoted to
farmland shows its inadequacy in the face of the channel islands Ravens.
They are common on Santa Cruz Island, including cliffs above the surf. I
haven't checked for Crow records there, there may be some--but surely only
as vagrants. One may suppose a variety of logical explanations for the
complexity of their separation, and their co-existance in some places as
pointed out on Calbird recently, but unanswered questions remain. Looking
at this species around the northern hemisphere one sees an incredible
ability to adapt to any climate extant.

On another note. The return of "Jamie's Grackle" to Preisker Park is
interesting to me. Where would it have wintered? Are Grackles
migratory?
Yes and no; some are, some aren't. Some Great-tails (Walter Wehtje could
give us sub-specific/population differences on this) are migratory, some
aren't. The northern population of Common Grackle is migratory, the
southern population sedentary. A small northern population (largely
Appalachian) of "purple" Common is migratory, the Florida population
sedentary.

The visual field-mark problem with Jamie's Grackle (Quiscalus chavezi) seems
to center on the lack of bronzey edges to the scapulars. If the scaps had
bronzey edges there would be ID mark corroboration for a theory of the
infintesimal chance that it is from the (short-distance) migratory "stonei"
race of Common. I spent lots of time looking for this in all light
conditions last spring/summer and it wasn't there (although it should be
looked for again now when the bird is presumably in fresher plumage). This,
plus its confusing variety of calls and its behavior make the hybrid
hypothesis clearly the best.

Does its return change anyone's opinion of what it may be?
No.

Should it be caught and a DNA sample be taken? Does anyone care?
Emphatically yes, and yes.

Brad

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