Friday, September 17, 2010

Sam's Lane - Sparrows in Boulder County Open Space

Early last week one of the Boulder area birders reported seeing some Cassin's Kingbirds along a trail he referred to as Sam's Lane. I knew the area but wasn't familiar with the path, and the report indicated some gate jumping was involved - so I decided it was a perfect lunch time destination.

The Kingbirds had moved on, but I had a nice walk, and some good practice sorting out fall sparrows.

The Vesper Sparrow: (note the complete eye-ring and rufous coverts peaking through above the wing-bars)

Brewer's Sparrows were also around, these are really tough to distinguish from Clay-colored Sparrows in the fall, but I am calling this a Brewer's based on the less distinct facial patterns, and by what appears to be more streaking in the nape, (the gray area that constitutes the back of the neck- below the head markings and above the wings and back):

In addition to the Vesper and Brewer's Sparrows there were a large group of Savannah Sparrows that were primarily foraging on the ground. One of them popped up to the fence briefly, stopping to pose before dropping back to cover.

For Savannah Sparrows, I find that in the field the most noticeable traits are the golden lores (area between the eye and bill). In this cloud-shaded picture they don't stand out as clearly as they can in direct sunlight. For me, sparrows still get a lot of scrutiny when I am looking through my pictures after the fact to make sure my initial identification is correct. When looking at a Savannah Sparrow more closely - either through bins in the field or at the picture above I note the eye-line that breaks the white eye-ring. Compare that to the Vesper Sparrow at the top of the page where the eye-ring is complete. One final mark for the Savannah Sparrow is the length of the tail. It is short enough to appear broken, and a good comparison against other known sparrows in the field.

No comments:

Post a Comment