Thursday, April 4, 2013

MA - nigrideus on the move 04/03/13

This morning I decided to look no further than the rolling fields around Gill. Seemingly each field of rough pasture, and many local yards, have been full of American Robins in the last few days. Among the typical grey-mantled robins (Turdus migratorius migratorius) were several birds of the blackish-mantled form T. m. nigrideus which breeds in the Canadian Atlantic. Despite looking for them in most flocks of Robins that I come across, I think these could be the first that I've seen locally in Gill, or at least the first that I've had the chance to view and digiscope. The birds were part of a larger movement of American Robins today and I made a crude estimate of about 1200 birds in loose flocks along Main Road between Mountain Road (north end) and Munn's Ferry Road. Within the feeding flocks I also found Killdeer, Common Grackle, Red-winged Blackbird and Brown-headed Cowbird. Eastern Phoebes seem to be pretty widespread already with males singing from the most of the properties along Main Road and North Cross Road in Gill.

*All the images below were taken in Gill, Franklin Co., on April 3rd 2013 and digiscoped using a Panasonic Lumix FZ7 and Swarovski HD scope.

 American Robins - North Cross Road. Typical scene from the first few days of April.
Many fields in Gill currently host such flocks.

Male American Robins - notice the 'sooty', blackish appearance and overall color of the bird above (T.m. nigrideus). This bird shows no contrast between the nape and the rest of the upperparts except for the rump which is contrastingly gray. The bird below (T.m. migratorious) it shows a fairly neat contrast between the black rear crown and gray mantle feathers, the mantle being only slightly darker than the rump. The blacker-mantled birds are distinctive and stand out in a loose feeding flock of robins.

T.m. nigrideus - All three images above refer to the same male on Munn's Ferry Road, April 3rd, 2013.

T.m. migratorious

T.m. nigrideus - (male) right of shot with unidentified female at left and possibly another male nigrideus at the rear.

T.m. nigrideus - head, nape and mantle all relatively uniform blackish.
T.m. nigrideus - same bird as above. Most of the throat is blackish with only a small amount of white below the bill.
Compare with the bird below (T.m.migratorious or intergrade) which has a much more extensive white chin and throat.
T.m. migratorious or intergrade - two images of this male certainly show some blackish centered feathers in the mantle but the overall tone is still quite gray, not anywhere near as dark as the clearest examples of nigrideus. Assumed to be an intergrade between the two forms. Birds like this seem to be at least as frequent as the better examples of nigrideus in the flocks around Gill.

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