Anchorage Daily News

Picture this.

You're riding down the new bike trail that parallels the Elmore Road extension south of Tudor when suddenly you're startled out of your greenbelt reverie by the scream of some invisible raptor.

SCREEEECH!

Will it swoop down and knock you off your bike? Scanning the green bog between you and an electric power station to the west, you see no sign of a hawk or eagle.

So you ride on.

A few days later, however, you're pedaling down the same bike trail when the same bird of prey cries out at the very same place. So what's going on here? Another chapter in the Big Wild Life of Anchorage?

Not exactly. This time it's more like simulated life. In fact it's an amplified recording of a raptor (probably a peregrine falcon) that the Chugach Electric Association plays repeatedly at its substation there to scare away ravens.

As veterans of past Anchorage power outages might recall, ravens here have a habit of perching on high-voltage transformers and electrical relays around town and bringing down the system, partly due to their enormous wingspans.

When one wingtip touches a pole that runs to ground, and the other touches an energized line loaded with 34,000 volts of power, the raven dies in a puff of smoke and lights go out all over Anchorage.

Some of the outages are legendary. A raven-induced explosion at the Tudor Road substation in 1982 cut off power to more than 200,000 Southcentral Alaska customers and led to car accidents at intersections that lost their signals.

Seven years ago, a raven that shorted out a South Anchorage substation also knocked out TV sets just before the kickoff for the 2001 Super Bowl game between the New York Giants and, yes, the Baltimore Ravens. (The Ravens won the game, 34-7.)

So Chugach has a stake in keeping big birds away from its equipment. That became even more obvious after ravens were implicated in four successive power outages from 2001 to 2003, according to Chugach spokeswoman Patti Bogan.

The next year, the utility invested in equipment marketed by Bird-X, Inc. of Chicago to reduce conflicts at some of its most raven-riddled substations. Included in the package were spike strips to discourage birds from perching on cross-bars, insulated coverings to protect energized power components, and a "squawker" to scare away ravens.

The latter was especially effective at the Elmore substation that recorded a raven-induced power outage the previous year, according to Bill Bernier, Chugach's director of substations and line operations.

Some of the "audio scarecrows" Chugach acquired emit a high-pitched tone that birds find offensive even though it's barely audible to humans. Others, like the raptor-and-prey sounds installed near Elmore, make a lot more noise.

Bernier says he was told the recording there was programmed to mimic the distress call of a raven. But Audubon Alaska executive director Stan Senner -- after hearing an excerpt -- thinks it sounds a lot more like the screech of a falcon.

"It's not a raven," he said. "Most of it sounds like a raptor of some kind. It could easily be a peregrine, or a gyrfalcon, or a goshawk."

Whatever it is, Bernier says, it's doing its job. "We haven't had an incident out there since it was installed."

Because it's so noisy -- lasting about 40 seconds and repeating every five minutes -- Chugach wouldn't consider installing it at a substation close to a residential area, Bernier said. But the Elmore substation is located at the end of an undeveloped dirt road that's closed to the public, so no one ever hears it.

At least they didn't used to.

Since Elmore Road (the southern extension of Bragaw Street) opened up last fall, the raptor screams regularly startle hikers and bikers.

But Senner commends Chugach for coming up with a nonlethal means for deterring ravens.

"If the point is to discourage birds, you just want to put together the most obnoxious sequence you can," he said. "So that's pretty good."

Find George Bryson online at adn.com/contact/gbryson or call 257-4318.ucc

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