Many gardeners like listening to a radio while they weed and seed or putter. Others wear headsets as they do their yard work. A growing number, however, are tuning in to birdsong. And for good reason.

The programming comes commercial-free, and the songs, calls and whistles are performed by some of the finest soloists in nature.

Composers and poets have tried capturing the melody and meter of birdsong. There’s Vivaldi in “The Four Seasons,” Beethoven with “Pastoral Symphony,” and Stravinsky’s “The Nightingale,” among others. For birdsong in poetry, read Shelley or Keats.

To the practiced ear, there is birdsong and there are birdcalls. Scientists say they differ.

“Birdsong is what people may typically hear — longer vocalizations used in courtship and territoriality,” says Greg Budney, curator of the audio collection at the Cornell Lab of Ornithology’s Macaulay Library in Ithaca, N.Y. “Calls are vocalizations that parents might make to communicate with juveniles. There also are the intimate calls adults give one another as they make an exchange at their nest. A flush call would be the squawk of a great blue heron if you surprise one near a swamp.”

Alarm calls

Deer hunters who try making themselves invisible to their prey from tree stands know all about alarm calls. Blue jays, for example, serve as one of the best early warning systems in the forest, delivering a series of piercing shrieks whenever they come across something or someone that doesn’t belong.

“That’s different from their normal sounds,” Budney says. “And it’s understood by many species other than blue jays. It tells them there’s trouble in the area.”

Cornell University has gathered what is reputed to be the world’s largest collection of wildlife sounds, with about 165,000 individual recordings. Some 6,700 species of birds are included in the audio mix along with another thousand amphibians, “singing insects” and mammals.

It isn't just male birds that can carry a tune. Many females, like the cardinal above, also have a singing repertoire. Birding by ear is an effective way to identify certain species.

That makes Budney, who helps oversee the university’s collection, a good person to ask just why it is that birds sing.

“It’s much more sophisticated than we imagine on the surface,” he says. “We tend to imagine a bird on a branch spilling forth all these sounds, willing to be heard. But there’s a message in all this: One bird may be telling another ‘this territory is occupied. Don’t come in here unless you want a confrontation.”‘

Acoustic battles

Battles between birds of the same species often are acoustic. “They’re assessing one another’s strengths by the way they sing — the size of their repertoire.”

Mating is involved, too. “Females listening in are trying to obtain the best quality resources for raising their young,” Budney says. “One more song in a male’s arsenal can be indicative of better genetics.”

It’s one thing to identify birds by sight; it’s quite another to ID them by sound. That takes familiarization.

“By learning the bird sounds, you kind of force yourself to become a field ecologist in a lot of ways,” says Dave Sumpter, executive director of PEER Inc., a nonprofit environmental research firm in Tampa, Fla.

“If you’re a gardener and that’s the perspective you want to use for your birding, study your pocket guides,” Sumpter says. “Spend a little time up front learning what species frequent your area.”

Stop, look, listen

In remarks prepared for a recent Florida Birding & Nature Festival in St. Petersburg, Sumpter suggested that people start small if they’re new to birding by ear.

“Concentrate on the most difficult-to-see birds,” Sumpter says. That could mean warblers and vireos that prefer perching high in the tree canopy. That also might mean marsh birds like rails, adept at hiding in reeds and rushes. Meadow birds like bobolinks, sparrows and meadowlarks also qualify because they like hunkering down in brush piles and tangles. You can make the sorting job easier by familiarizing yourself with birds according to their range and seasons, habitat preferences, the time they feed and their structural distribution.

Along with dividing the birds you’re most likely to hear by region, Sumpter suggests logging them by the sounds they make.

“One grouping would include the American robin,” Sumpter says. “Its sound is like a whistle. The scarlet tanager has the same song, but it sounds like it’s singing with a sore throat. The rose-breasted grosbeak sounds like a robin that’s had voice lessons.” A variety of aids are available to help match the sound with the bird. That includes audio CDs, hand-held identifiers that play back the sounds certain birds make, and books. You might also seek out other, more experienced birders and take nature walks.

Stop, look and listen while you garden or during meanders around your neighborhood.