Monday, June 04, 2007

Brightly-colored Birds

On Saturday I helped lead a DC Audubon field trip to Little Bennett Regional Park in Montgomery County. (Go there for photos from Saturday.) Little Bennett covers 3700 acres of bottomland forest and old fields in various stages of succession. The habitats preserved in the park have become more valuable in the light of recent changes; land around the park that was open space until very recently is now occupied by subdivisions. We visited Little Bennett in search of breeding birds that can be hard to find in the DC area. We started out at the Kingsley Trail, since that winds through a mix of habitats, and then moved on to a spot on the north end of the park. About a dozen participants attended, which is a good size for a field trip.

Prairie Warbler / Photo by Steve Maslowski (USFWS)

We heard and saw several prairie warblers along the course of the Kingsley Trail and Purdum Trail, starting with a bird singing near the parking lot. Later in the morning, we had a great look at a male as it foraged, popping in and out of some low shrubs. Along the Kingsley Trail, we had eastern bluebird, white-eyed vireo, yellow warbler, black-and-white warbler, Louisiana waterthrush, scarlet tanager, and Baltimore oriole. A northern parula was singing near the schoolhouse, which hosted an eastern phoebe nest in its cupola. When we walked uphill to the Purdum Trail campground, we found cedar waxwing, pine warbler, ovenbird, and field sparrow near the top.

The pine warbler gave a lesson in the trickiness of distinguishing trills. As I looked at a pine warbler through my binoculars, I could hear a trill, which I assumed was another male pine warbler. Soon enough, however, someone else spotted the real source of the song - a chipping sparrow.

Kentucky Warbler / Photo by Steve Maslowski (USFWS)

At the north end of the park, we hoped to find a Kentucky warbler that had been reported along the closed section of Hyattstown Mill Road. As we walked down the road, we had the opportunity to watch a singing Louisiana waterthrush and a yellow-throated vireo. Otherwise the road was fairly quiet. Finally, my co-leader spotted a Kentucky warbler, and it stayed in the open long enough for most of the group to get at least a short look. Before we left, we had a second, better look at a Kentucky warbler. This bird stayed at eye level and showed off its spectacular colors. As we returned to the cars, a bright red bird flashed across the road. My first thought was cardinal, but something did not seem right about the identification - the red was too bright, the red tail far too short. After conferring amongst ourselves and consulting our field guides, we concluded that the bird was a summer tanager, a southern species that breeds in a few locations around the DC area.

Scarlet Tanager / Photo by Steve Maslowski (USFWS)

One of the paradoxes of birding is that some of the most brightly-colored birds are also the hardest to find. Male scarlet and summer tanagers, for example, are a brilliant scarlet red. It is hard to find a brighter red among North American birds. Even cardinals have trouble competing against the tanagers. Looking at a field guide illustration, one might think that tanagers would be easy to spot, like cardinals. Many warblers are also brightly colored, at least in breeding plumage.

The reality is that the bright colors and bold patterns of forest birds can be easily missed. In the case of warblers, like a prairie or Kentucky warbler, those bold patterns help to break up a bird's shape, while the typically olive upperparts and white or yellow underparts tend to blend into the foliage. Tanagers present a special problem because they spend most of their time in the upper canopy. At the tops of trees, their bright colors sometimes work against a bird watcher because they disappear in the patterns of dappled light.

On this occasion, we would not get a second look at the summer tanager, though we could hear the bird singing nearby. Brightly-colored birds may not always be easy to spot, but they offer a high reward to those that can find them. On Saturday we were rewarded with stunning looks at great birds.