Friday, March 27, 2009

Not So Silent Spring

Via the Acoustic Ecology Institute, I discovered this article about the effects of noise on wildlife.
Some excerpts:

A male European blackbird was terrorizing the neighborhood. For several months, he started singing at around 5 a.m. each day, but this was no ordinary song. The bird imitated the sounds of ambulance sirens and car alarms at a jarringly life-like volume. It even produced cell-phone ring tones that went unanswered for hours.

Hans Slabbekoorn, an assistant professor of behavioral biology at Leiden University in The Netherlands, [...] started asking people to send him recordings of the off-kilter blackbirds. Sure enough, what he got back was pitch-perfect imitations of urban noises, including not just sirens and car alarms but even the distinctive sound of a golf cart backing up—mimicked by blackbirds living near a golf course.

Living amid a growing cacophony of man-made noises, the blackbirds started incorporating human sounds into their repertoire.

Blackbirds aren’t the only animals changing their tunes. As human noise intrudes on nature—from freeway traffic noise to jets screaming over the rainforest—scientists are starting to believe the acoustic environment is far more intricate and fragile than they ever imagined. Long regarded as a random collection of bird songs and animal cries, the natural soundscape might actually be a coordinated symphony, with animal calls spread carefully across the acoustic spectrum. Now, researchers are getting the first glimpses of what happens when humanity’s choir drowns out whole sections of that spectrum. Animals ranging from blackbirds to beluga whales are changing their calls or switching them to new frequencies. Others are adapting in ways so powerful that they may be triggering the first steps in an evolutionary shakeup. And some animals are disappearing altogether.

[read more - via Conservation Magazine]

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