October 20, 2011

The present consensus, based on the opinions of about five people, all knowledgeable birders, is that the bird is a Savannah Sparrow.   (I'm not a knowledgeable birder - the opinions here are all from other people.)

Three people (of these five) saw the bird in person, and all noted that its behavior was very different than the usual Savannah Sparrow (SS) behavior.  This bird kept low in the grass at all times, even though there were clumps of grass or low brush where it could have perched if it wanted to.  It crept around, almost like a mouse.  Also it came within 20-30 feet of a group of 15 people and did not fly away as we moved around. 

One of the three was not part of our group and only happened by.  He birds this area regularly (i.e., is a local expert) and after observing the bird became quite confident that the bird was a Lapland Longspur (LL).  The other two people were less certain, thinking at first that it could be either a SS or an LL, but did not openly question the LL identification at the time. 

When we left the area, I'd say most people in our group felt we'd seen a LL, a good feeling because we were actively looking for this species.  There'd been a report of a sighting of a LL in this area, and that's why the group went first  to this particular piece of the Hayward shorline.

A quick glance at the Sibley field guide show that the Lapland Longspur (LL) look "similar" in that they are both sparrow-like and about the same size.  When you consider that there can be slight variations among individual birds of a species such an observed bird doesn't always appear exactly as depicted in the field guide, it's easy to come to a quick conclusion based on observed similarities rather than on small differences.

While photos don't convey behavior such as we saw, they do give opportunity for more relaxed and careful examination after the fact, and people who weren't there can also examine them.   The two people who saw only the photos were convinced the bird was a SS.  This is based on a detailed comparison between the actual bird and what the field guide Sibley Guide to Birds) shows for a SS and a LL, and of course on their own field experiences. 

Here are their comments, paraphrased.

--The bill, being larger and having a slight convex curveature along the top ridge, is SS-like.
--The legs are SS orange-ish rather than darker like an LL.
--The plumage lacks the reddish (i.e. "rufous") sides that a LL would have (lacks "rufous-edged greater coverts")
--The lores (the area just behind the beak) was more indicative of a SS.
--The markings in the auricular frame (the area of the bird's head in the vicinity of the ear) are bolder in the LL than the SS.  The bird lacks these bolder markings.
--The streaking on the breast and flanks is too crisp for a Longspur.

Finally, when the local expert had a chance to view the detail in the photos, he decided that the bird is a SS.

Still unexplained is the unusual behavior shown by this bird.  (Could it have been something peculiar to just this individual, maybe a physical defect?)  But the overall consensus is that it's a Savannah Sparrow.

Julie (who first spotted this bird and noted its odd behavior) and I found the correspondence from these five people about the identification of this particular bird fascinating. What fun!