Listening for the Ivory-billed Woodpecker
In James Tanner's landmark 1942 book, The Ivory-billed Woodpecker,
he observed that the best way to find these birds in their dense forest
haunts is to listen. Indeed, in nearly three years of field work,
Tanner always found an Ivory-billed Woodpecker first by hearing it,
then by going toward the sound.
 unit (ARU) Photo by Susan Spear/CLO |
So in 2004, when the Cornell Laboratory of Ornithology began to search
for ivory-bills in the Big Woods of Arkansas, listening had to be part
of the plan. But all the sharp-eared birders that could possibly be
recruited for this secret search could barely scratch the surface of
the vast area to be covered. And if a searcher in the field heard a
faint call, like the far-off toot of a toy trumpet, the sound would be
gone in a heartbeat, leaving the searcher to wonder--was that the nasal
kent call of an ivory-bill or another bird in the distance with a
similar-sounding call?
The solution was to deploy electronic listening devices called
autonomous recording units (ARUs) at dozens of sites throughout the
search area. ARUs could listen for weeks at a time, recording every
sound for careful analysis later.
Listen to some the recordings the search team recovered:
Ivory-billed Woodpecker web site, Cornell Lab of Ornithology
Related articles:
Hope Knocks. BirdScope, Summer 2005.