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The black-throated gray warbler has two very distinct songs. Photo courtesy ibc.lynxeds.com

Birds must pack a lot of meaning into a song

Let’s try a little exercise. Your task is to compose a message that communicates everything that you need to share with others in life, and, here is the hard part, the message can be no longer than two seconds. By others this would include your spouse, kids, parents, neighbors, the banker, everyone.

What message could possible cover all your needs? Seems like an impossible task, doesn’t it? And yet, as the spring chorus starts up, that’s just about how long a great many birds have to state their case through song.

Consider what the MacGillivray’s warbler living in a willow patch up on Wagner Butte has to pack in that brief message. “I am a MacGillivray’s warbler!” To other males: “Stay out of my territory! This food is mine.” To other females: “I’m the strongest and best potential mate in the area.” To other males again: “I have a mate. Stay clear!” And so on.

OK. Many birds also have calls, calls that warn of predators, calls that keep a group together and inquire as to where a wayward fledgling has wandered off. Still, a MacGillivray’s warbler relies heavily on that two-second song.

There is another rather select group of birds. These have two very different songs and include some warblers, some sparrows and even a few flycatchers. Locally, the black-throated gray warbler belongs to this group.

The most commonly heard song of the black-throated gray warbler is buzzy, or full of “Z's" as some field guides describe it. Now if you get up before dawn and head out into the forest when the morning is just a patch of pale sky on the horizon, you will hear a very different song. It is hurried and sweet. The first time I heard its pre-dawn song, I was certain the bird had to be addled in some way. The song was bizarre — bizarre only to birders like me who like a full night’s sleep.

Why do some species have two songs while others require only one? This is a question I have been investigating at length.

Some who have studied this question conclude that one song is intended for males (territorial defense), while the other song is intended for females (mate attraction). After studying this for years, I’m not convinced this is quite right. I’ll give you my thoughts in a later column.

But why two songs? One song works just fine for juncos, tanagers, buntings and MacGillivray’s warblers. Maybe one song carries farther. Possibly one song takes more energy to sing than the other. They might save the demanding song for the special situations that call for it.

All of this shows just how little we understand about bird song. As a researcher, sometimes I feel as if I am in a Cambodian village hoping to learn the local language — I am allowed to listen to the conversations and watch the people go about their business, but I am not allowed to interact with them in any meaningful way. If I am patient enough, maybe, just maybe, I can figure things out.

This is about where ornithologists are. Just give me just a few more decades of study. I’m sure I can learn to speak warbler.

Stewart Janes is a biology professor at Southern Oregon University. He can be reached at janes@sou.edu.

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