Birdsong. Another facet of bird study a person could make a career out of or a lifelong hobby. (It helps if you can hear very well, although there now are various instruments available.)
Birdsong is an appropriate topic at present. The first red-winged blackbird song of spring is eagerly awaited and is pleasant to the ear. To humans this male announcement of his arrival, his territory, his availability to a suitable female, soon becomes a barely tolerable cacophony near every red-winged breeding colony. Which says more about us than it does about red-winged vocalizations; they’re obviously important to the birds. No predator can fail to know where nests and nestlings are, let alone the adults, but the need to communicate must supersede secrecy for them.
It seems obvious that birds need to, want to, evolved to communicate. Almost all bird species have an organ called the syrinx. The syrinx is a kind of second larynx, which humans possess and produces our voice, and it is unique to birds. Birdsong is not altered by resonating in the birds’ throats or mouths; thus, many bird species can sing complete songs with full mouths or closed bills. Some can produce two separate sounds simultaneously. It all suggests how important birdsong is to birds.
Birds have songs and also calls. Songs seem mostly to be used in reproductive activity, as in courtship and attending nests and nestlings. Calls are used for warning of enemies, begging, flock cohesion and scolding.
The familiar cheery robin’s song, so welcome when robins return, can be less to human taste on a 5 a.m. summer sunrise. The “dawn chorus,” often many birds welcoming the start of a new day during breeding season, can be loud if you’re lucky enough to live near good bird habitat. Birdsong tapers down all too soon, as the breeding urge dissipates.
What do birds that lack a syrinx do to produce a sound? Some snap their bills, or pairs of birds may hit their bills together. Some birds make characteristic noises as air passes through their feathers. A few species can grunt, hiss, plop air sacs or drum. In courtship, whatever works.
Comes now the discovery of another mechanism for producing a courtship song. The male of a rare South American bird, the club-winged manakin, creates a high hum, similar to a sustained violin note, by rubbing specialized wing feathers at about 100 cycles per second.
The club-winged manakin is a small bird, sparrow-size. Its sixth and secondary wing feathers have enlarged and hollow shafts; when these feathers are rubbed at their natural resonant frequency, all nine wing feathers resonate at 1,500 hertz. A violin note close to an F sharp. A second harmonic tone is also produced. One investigator commented that these feathers have become a kind of tuning fork.
Next the investigators will probably find that female club-winged manakins have acute hearing in the F-sharp range of notes. I’d bet on it.
This column first appeared in the March 31, 2010, News&Guide
Field Notes: It’s green everywhere. During our cool, wet spring, plants have responded and plant life is booming. It can almost look tropical on a damp morning. I hate to say it but there could be increased fire danger later in the year. Practice good fire prevention starting now.
It has been a memorable couple of weeks of colorful birds hanging around Jackson Hole and the region. Bullock’s orioles, Western tanagers, black headed grosbeaks, goldfinch, lazuli bunting and hummingbirds make a pretty sight.
On cold, wet days, birds like the Western tanager come close to earth. On sunny days they’re still around, but higher in elevation.
There were several sightings of rose-breasted grosbeaks — an unusual sight — in town. Some Western tanagers were spotted at Cottonwood Park, reported Claudia Gillette. In Teton Valley, Idaho, Susan Patla spotted a number of warbling vireo, dusky flycatcher, both Hermit and Swainson’s thrush, MacGillivray’s warbler and an unexpected plumbeous vireo, singing.