See update at the end of this post.
On Saturday I lead a trip for the Brooklyn Bird Club to Fort Tilden and Jacob Riis Park. The wind conditions were less than ideal for fall migrating birds, but there were some highlights, including a very oddly plumed sparrow.
Overnight Northeast winds switched to the east and by late morning were nearly non-existent. Flocks of migrating Blue Jays looked confused as they moved both east and west across Ft. Tilden and Riis Park, circling the area. The best sighting of the day was a female Dickcissel located at a stretch of grass near the boardwalk just east of Beach 169th Street. Seconds after spotting the Dickcissel, Tom Preston and I noticed an odd sparrow perched nearby. There were several Savannah Sparrows and Song Sparrows in the vicinity that flushed as we walked across the grass. This bird's general shape and structure was that of a Savannah Sparrow, but with muted colors that seemed odd and unfamiliar to me. It had the yellow facial wash one would expect on most savannahs, but, among other interesting features, had an unusual buffy-colored collar. The "Ipswich" Sparrow race of savannah is very pale, but should be noticeably larger than our typical race. James Rising's "A Guide to the Identification and Natural History of the Sparrows of the United States and Canada" mentions that there are 12 subspecies of Savannah Sparrow, so perhaps it is just a form that is uncommon around New York City. I've also considered that perhaps this individual bird has a pigment deficiency. Jason Conradt and Steve Walter were present and took some decent photographs of the bird. If you have any insights, I'd appreciate your comments.
"The sparrow looks to me like an erythristic Savannah Sparrow. That is an individual showing only the Phaeomelanin (red) pigments and lacking eumelanin (black pigment)."
I really enjoyed the following, surprising email exchange sent to me by Jason Conradt:
From: Jason Conradt
Subject: Fwd: Savannah Sparrow question
On a lark I thought I'd email David Sibley and see what he thought. He thinks it might be leucistic. This is a fun little mystery.
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On Sep 21, 2008, at 9:31 PM, Jason Conradt wrote:
Hi Mr Sibley.
I'm a birdwatcher from Brooklyn, NY (Chelmsford, MA originally) and I've stumbled across a sparrow I can't identify. I think it's an Ipswich Sparrow but the dark streaks in the primary and covert feather tips are very pale. I was wondering if you thought this could be a partial albino or possibly another variant that isn't illustrated in your book.
I saw the bird on a walk led by Rob Jett of the Brooklyn Bird Club at Fort Tilden. I attached some photos that I took and you can check out my Flickr page if you're interested in seeing more of them. If you have time please let me know what you think.
My wife and I love your books.
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From: David Sibley
Date: September 22, 2008 9:36:38 AM EDT
Subject: Re: Savannah Sparrow question
From the photos I would say this is NOT an Ipswich, too much yellow on the face and too much red in the wings and body. Ipswich should look grayer overall with hints of pinkish, and virtually no yellow on the face. So this is most likely to be a "dilute plumage" or "leucistic" Savannah from one of the common subspecies, lacking some of the brown or black pigment. Interesting bird.