October 22, 2014

What’s up with that fancy chapeau?

bird938-pileated1

bird938-pileated1Linda Haines of Ridgefield was excited last week at having seen and photographed the accompanying Pileated Woodpecker on the ground in her yard. She had not seen a Pileated on the ground before, and was pleased to capture it on camera.

“Seems to have been diligently digging for some food,” she wrote. “They eat insects and especially like carpenter ants, which is what they may have found in our old tree stump.”

Pileated Woodpeckers are actually more likely to be seen on the ground than most of our woodpeckers (except for the Northern Flicker, which prefers the ground). They like stumps and fallen trees — which is probably why they have been nicknamed the “logcock.” Linda Haines’ pictures of a Pileated Woodpecker investigating a stump for insects show  the bird both with and without its crest. Why was it raised?  Linda Haines’ pictures of a Pileated Woodpecker investigating a stump for insects show the bird both with and without its crest. Why was it raised?

However, Linda captured an even cooler thing: A Pileated’s head in both normal and display mode.

As you can see from the pictures, the difference is quite striking.

But why did this woodpecker put up its crest and why do some birds have crests in the first place?

Ornithologists have a number of theories about the use of crest feathers, also found on other local species — probably the most common in our yards are the Tufted Titmouse and the Northern Cardinal.

One theory is that they simply make the bird look bigger and more imposing. They can be flashed when there’s an intruder or another bird that the crest-topped one wants to chase off — we’ve seen that at the bird feeder when a titmouse is defending its position while on the feeding platform.

Another use is in mating displays. This may be truer with a Pileated Woodpecker than a Tufted Titmouse. The former has a bright red crest, the latter a dull gray one. Ornithologists believe that a healthy display of plumage is one of the aspects that courting birds check out in potential mates. In some species, the crests are visible only during breeding season.

Still another possible use is as a sign of alarm. It could be a silent signal to other Pileateds, or simple be a show of force, as the first use. In some species, such as Cockatiels, the crest may be a more sophisticated means of communicating with others in their flock.

The most interesting possibility is the use of the crest as a sound sensor. In some species, head feathers may be part of their “hearing.”  A crest could, in effect, be an antenna, raised to sense vibrations in the air — especially from a potential predator. It could act like external ears. For a big bird on the ground, this “radar” antenna might be especially advantageous since its field of vision is much less than it would be higher up on the side of a tree.

I have several large ornithological textbooks — one more than 1,000 pages — and it’s remarkable how little information on bird crests is in them! Perhaps it’s an area where research is needed.

Coming up

Birding Classes: Wood Warblers and other Neotropical Migrants, Saturday, May 19, Birds in their Habitats, Saturday, May 26, 9:30 to noon,  $15/adult — kids free, Audubon Greenwich parking area at 613 Riversville Road, 203-869-5272 x230, greenwich.audubon.org

Spring migration bird walk, Tuesday, May 22, 7:30 to 9:30 a.m., North County Trailway; Bedford Audubon, www.bedfordaudubon.org, 914- 232-1999.

Spring Migration Bird Walk with Michelle Eckman Saturday, May 19, 9-11 a.m. Connecticut Audubon Society, Center at Fairfield, 2325 Burr Street, Fairfield.  

Copyright 2012 by Jack Sanders. Send sightings or comments to: jackfsanders [at sign] gmail.com, or to Bird Notes, Box 1019, Ridgefield, CT 06877. If you need help identifying a bird, try your local nature center. If you find an injured bird, call wildlife rehabilitator Darlene Wimbrow of Redding, 203-438-0618, Wildlife in Crisis of Weston, 203-544-9913, or Wild Wings of Greenwich, 203-637-9822. The columnist’s website is www. sandersbooks. com.