On March 10, the first eastern phoebe of the season perched on a red maple branch outside my office window. It sang its buzzy song, “fee-bee,” repeatedly for several minutes.
When I heard it next, it was still nearby, but out of sight and singing the same easy-to-recognize song. A few minutes later, it moved across the road and continued to sing.
On March 21, a different singer caught my ear. This song came in short phrases, each different, but repeated only once. The singer perched in a dense thicket, but I could hear that it also changed locations every few minutes.
Call confirms identity
Short variable phrases repeated only once told me the singer was the first gray catbird of the season. Its distinctive call note — “Mew!” — confirmed the bird’s identity. And on March 30, a high-pitched monotone trill greeted me as I walked down the driveway to the garage.
The first chipping sparrow of the year had returned. It flew from treetop to treetop on the perimeter of the yard as it sang.
Why they sing
Birds sing for two reasons. The message depends upon who hears the song. Male birds establish and defend a territory from other males of the same species by singing from perches around and within the territory. In this sense, bird song is a “keep-out” signal.
Other males know that if they violate a territory’s boundary, they will be attacked. So they respect territory owners. Furthermore, a single male can create the illusion that a territory is overrun with competing males, and therefore undesirable, by singing from many perches within the territory. That’s what the three examples I opened with were doing.
By singing from a variety of perches around a territory, one male creates the impression that a given piece of habitat is already occupied by several males. That message motivates potential intruders to find another place to nest.
Mockingbirds exaggerate the illusion by singing many different songs each time they move to a new perch. To other males, it sounds as if many males occupy the area, so they look for areas where there might be less competition.
Thus, the territory holder defends his space by deception. Why battle many males, when unoccupied and undefended habitat may be just a few wing beats away?
Mockingbirds often take this deception to extremes by singing all night long. If you hear a bird singing between dusk and dawn and it’s clearly not an owl or a whip-poor-will, it’s likely a mockingbird or a yellow-breasted chat, another versatile singer.
During the nesting season, males of these two species can be heard any time of day or night. It may seem like overkill, but wandering males cannot mistake the keep-out message.
The opposite sex
The second function of male song is to attract females. It says, “I’m available, I’ve got a nice territory, I can provide for you, let’s be a couple.” Though some might call such vocalizations love songs, biologists prefer to keep emotions out of the equation.
Song is an essential part of the pair-bonding process. Both male and female birds also vocalize to communicate everyday information. Ornithologists label these sounds “calls.”
Short, nonmusical chips, chirps, and whistles uttered year round convey information about location, food sources, and social position. Other calls rally broods and indicate alarm, danger, aggression, and annoyance.
In human terms, calls are the vocabulary of daily conversation. Vocalizing may seem a dangerous way to communicate because it draws attention to the singer. Hawks, owls, and other predators might use sound to zero in on tasty songbirds. But part of the beauty of voice is its ephemeral nature.
Sound leaves no evidence behind. Once uttered, songs and calls vanish into thin air, so predators can’t use sound to locate vocalizing birds.
And if danger threatens, birds simply stop talking until the threat passes.
As you savor your morning coffee over the next few months, enjoy the music of birds. It’s beautiful, and it’s free!
STAY INFORMED. SIGN UP!
Up-to-date agriculture news in your inbox!