Katahdin trip yields 9 warbler species

Recently I was in the northern part of Baxter State Park with family. It was wonderfully scenic around Traveler Mountain, and its trails much less crowded than those in the southern part of the park. We camped near a group of the Friends of Baxter State Park. Some of them were birders.

We pooled our lists of warblers seen that weekend: black and white bay-breasted magnolia warblers, redstarts, yellow throats and more. Nine warbler species were found – we were pleased.

I enjoyed seeing a Swainson’s thrush, a thrush of the northern woods. This one had probably come from Canada and is now headed for Central America. It was wearing immaculate, brand-new brownish-green feathers and buff-colored “spectacles.” This thrush was formerly called the olive-backed thrush.

Another bird was not an “everyday” bird in the Bangor area – a yellow-bellied flycatcher. A half-dozen were in a tree, flying out to catch an insect, then flying back to the same perch. They are relatives of the well-known phoebe.

The yellow-bellied flycatchers were sporting their newly grown feathers – olive green and yellow. I was close enough to see their “rictal bristles,” short feathers consisting of only a shaft, sticking out around the base of the bill.

Rictal bristles are only about a half-inch long and surround the bills of birds that catch flying insects. Flycatchers – a family of bird species including phoebes, whip-poor-wills, swallows and redstarts – have rictal bristles. They all catch flying insects.

It was formerly thought that the rictal bristles functioned like a net, helping to bring insects into the bird’s mouth. To test that hypothesis, ornithologists removed the rictal bristles from flycatchers, and observed how they caught insects. No change.

They then filmed flycatchers catching insects, and watched the films in slow motion. They found that flycatchers caught insects in the tip of the bill, not in the open gape – the mouth. These results indicated that the rictal bristles did not function as a net to help catch the insect.

Current hypotheses are that the rictal bristles may have a sensing function, or that they may have a role in protecting the bird’s eyes from hard parts of insects during the capture. Think about how hard a fly hits a light, or how hard a dragonfly hits a car windshield. A bird can’t afford to lose an eye.

Also, think about this as you watch a phoebe when it flies from its perch to catch an insect.

For information on Fields Pond Audubon Center, call 989-2591.