Published April 11, 2010, 12:04 AM

ALWAYS IN SEASON: Behold, the bird sounds of spring

Birds make noise in a variety of ways. Certainly, singing is one of these, and spring is the season to appreciate bird song.

By: Mike Jacobs, Grand Forks Herald

This week I’ve been hearing bird noises.

Not bird songs.

Not bird calls.

Bird noises.

Birds make noise in a variety of ways. Certainly, singing is one of these, and spring is the season to appreciate bird song.

Robins.

Meadowlarks.

Song sparrows.

Each of these produce songs that evoke the season. Many other species produce noise that could not be considered musical, but which is equally evocative of the season.

Among these is the common snipe, whose distinctive noise is neither a call nor a song. Instead, it is the sound of air rushing through the bird’s tail feathers — modulated by the beating of its wings.

The noise of the snipe is less familiar now than it once was. The snipe has declined as agriculture has advanced. Still, snipe persist in their springtime displays wherever wet meadows occur.

The Red River Valley, despite its agricultural character, has quite a lot of these meadows, and so the valley is snipe country — and this is snipe season.

Snipe produce their characteristic noise through a process called “winnowing.” The noise is produced as air passes through the stiff feathers of the snipe’s tail. The snipe varies the tone of the noise partly by the rate of its wing beats and partly by the nature of its flight. A steep dive produces a prolonged winnowing sound. Shallow dives or steady flight produce a different, less anxious noise.

Anxious is a good word to describe the snipe’s noisemaking. It’s partly territorial, partly sexual, wholly natural and wonderfully wild.

And it is ephemeral.

Snipe make this winnowing noise in early spring, mostly to define and defend nesting territories. Males do the most winnowing, though females do it, too, according to ornithological research. Curiously, most winnowing occurs at temperatures a few degrees either side of freezing — from 25 to 40 degrees or so.

Winnowing may occur at almost any hour, but it is more frequent just after sunset.

As it happens, this is the time that I most often hear snipe winnowing most persistently, though I hear them in early morning, too.

Snipe are not the only birds that produce sounds that aren’t exactly vocalizations.

One day last week, I was puzzled by a kind of low pitch whine that I heard repeated over and over. I thought at first that it might be Tundra swans passing, but as the noise persisted, I realized that it came from a specific place — a point source, as environmental scientists describe it.

I eventually realized that the noise was made by sharp-tailed grouse, which produce a distinctive — even weird — noise by forcing air through sacks in their throats.

These birds are well known for their courtship displays — sometimes suggested as the inspiration for Native American dance steps. To see the males strut and prance requires a close approach to a dance ground, or lek. But to hear it requires only open ears and a quiet morning.

And proper habitat.

The population of sharp-tailed grouse has increased recently, probably in response to wider habitat choices and milder winters.

The snipe and the grouse have something in common. Their noise is evocative of spring.

This distinction they share with a couple of other species, Tundra swan and sandhill crane.

Like the grouse and the snipe, these two species produce sounds that are pitched rather lower than the ordinary bird song — but both the crane and the swan produce the sound in the same way that humans produce speech, by forcing air through the larynx.

What distinguishes the noise of the crane and the swan, however, is the distance the noise has to travel. Long necks make low sounds, as it happens.

These four noises — not songs, really, and in a couple of cases not even vocalizations — are emblematic of spring on the northern Plains.

The sound of the swan can be heard in Grand Forks, which seems to be along the route that swans prefer for their northward migration.

Likewise with cranes, though my experience is that they tend to be more common along the ridgelines that line the Red River Valley to the east and west — and especially the west — of Grand Forks.

But snipe and grouse are dependent on extensive grasslands.

Jacobs is publisher and editor of the Herald.

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