[NatureNS] Photo of large grackle, Barrington Passage

Date: Sat, 30 May 2009 11:35:29 -0300
From: iamclar@DAL.CA
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All:

It's good to have Clarence Stevens' detailed description of the large grackle,
which certainly matches Boat-tailed Grackle. Nonetheless, as promised earlier,
I have added to the evidence by placing Julie Smith's photo of the bird, along
with an annotated crop of the image, on the NS-RBA photo site. More photos for
the permanent record would of course have been desirable.

I sent the crop to two US experts, only one of whom has so far responded with
the statement that the photo image was "consonant" with Boat-tailed, but felt
unable to be wholly convinced. Nevertless, there are a couple of features that
might support the i.d.

1) The irridescence of the back: this is strongly blue, without purple tones,
while the largely hidden head is much darker, and possibly more purple-toned
(although that's tricky).

2. The size and shape of the tail: the tail feathers themselves seem broader
than a Common Grackles's, and the tail seems about as long as or shorter than
the wings, as shown by 2-headed arrows on the cropped image, although the
lengths of both must be partly guessed at. In addition, the tail is more
rounded than strongly wedge-shaped. As Clarence noted, the huge tail of
Great-tailed is more wedge-shaped.

So, take a look, for what it's worth.

Cheers, Ian

Ian McLaren

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