Wednesday, January 27, 2010

Counting Birds on the C&O Canal

This Saturday was the C&O Canal Midwinter Bird Survey, an annual event is sponsored by the DC Audubon Society. For the past four years I have helped to coordinate it. Unlike Christmas Bird Counts, which survey likely bird habitat within a 15-mile circle, the canal count is confined to a single national historical park. The count area is thus more linear as it follows the canal along a 184.5-mile strip of towpath and riverbank. Every year we aim for complete coverage, and the effort requires the help of over 100 observers, each working their own short stretch of towpath. Fortunately the survey has the help of many loyal volunteers who cover their sections year after year. To standardize the survey across such a long distance, volunteers keep separate checklists for each mile.

As I have done the past two years, I traveled down to DC to participate in the canal count. This time, I went with my friend Jed to help cover a stretch of canal near Little Orleans, an area I visited during previous counts. When we reached the starting point of our territory, we found that the river valley was filled with fog. While we could see and identify birds along the towpath, it was difficult to see much beyond the far side of the canal or any but the most low-flying birds above us. So during our first mile we recorded relatively few birds, with many of the identifications coming by way of vocalizations. Despite the lack of birds, I enjoyed the first section because of the beauty of the canal in the fog.

Fog blanketing a field next to the towpath

Fortunately, most of the fog burned off after about an hour. It seemed that as the fog lifted, the birds became more active as well. In the next hour we had most of our best sightings. An Eastern Phoebe was foraging actively near the riverbank – one of many that winters along the towpath. Shortly after that, I saw my first Hermit Thrush of the year. One Winter Wren perched near eye level at close range at the same time as another launched into its complex and eerie song. A Red-shouldered Hawk glided over the towpath calling loudly. At the very end of our second mile, we encountered the biggest flock of Eastern Bluebirds I have ever seen. At first I thought it was just a dozen or so, even though bluebird calls were coming from all directions. As we crossed into our third mile, it became apparent that there were dozens more. With the help of another team, we final determined that there were at least 50 bluebirds, and possibly more spread over the two miles.

For our last mile, the sky finished clearing, and the sun reflected off the many sycamores that line the canal in that section. We had a chance to watch two Common Ravens – a species I rarely see – playing in the sky together. Once again, a Winter Wren sang.

Jed and I saw a total of 27 species on our three miles of the towpath. As of this writing, the sightings reported through the DC Audubon website are up to 81 species. Since about 40 miles have yet to be submitted, the final species tally should be a good bit higher. Some expected species such as American Coot and Great Black-backed Gull are not yet on the list, but most likely will be once the final numbers are available.