SUMMER 2005/VOLUME 19, NUMBER 3
The Search for the Ivory-bill
How do you find a bird that eluded searchers
The anticipation was almost unbearable as we threaded our canoe through
the trees, going ever deeper into the ancient cypress and tupelo swamp that
enveloped us. As the dim light of dawn gave way to more penetrating rays,
I could see widely spaced, giant cypress trees towering above the smaller
water tupelos, which were so dense that they limited our view to no more
than 50 yards. Even though we were less than a mile from the road, this place
felt like wild, untamed wilderness. Along with the light came the sounds
of birds: Barred Owls, Carolina Wrens, Prothonotary Warblers, and the occasional cronk
of a Great Blue Heron.
But one bird affected me like it never had before. My heart skipped a little
each time a Pileated Woodpecker winged over the channel. It's hard to
imagine being frustrated by the sight of a spectacular bird like the pileated,
but I am. Each pileated was just that, another pileated. Where is the Ivory-billed
Woodpecker? Where is the bird we've come so far to find? I'm not
sure what I expected from my first day in this place, but one thing is now
crystal clear: finding an ivory-bill would be just like James Tanner had described--"like
looking for a flying needle in a haystack."
But one bird affected me like it never had before. My heart skipped a little each time a Pileated Woodpecker winged over the channel. It's hard to imagine being frustrated by the sight of a spectacular bird like the pileated, but I am. Each pileated was just that, another pileated. Where is the Ivory-billed Woodpecker? Where is the bird we've come so far to find? I'm not sure what I expected from my first day in this place, but one thing is now crystal clear: finding an ivory-bill would be just like James Tanner had described--"like looking for a flying needle in a haystack."
Ever since my first canoe trip through the swamp in April 2004, it seems that my every thought has been occupied by the Ivory-billed Woodpecker and the search to find it. Less than two months earlier, on February 11, Gene Sparling, a kayaker from Hot Springs, Arkansas, had sighted what he believed to be an Ivory-billed Woodpecker in the Cache River National Wildlife Refuge. On February 27, Living Bird editor-in-chief Tim Gallagher and his colleague Bobby Harrison, associate professor at Oakwood College in Alabama, saw an ivory-bill briefly in the same area. A handful of people searched in March, but when there were no additional sightings, I was asked to lead a larger team in search of the ivory-bill.
We organized 15 or so experienced field biologists to begin scouring the forested swamps where the sightings had occurred. When we arrived in Brinkley, Arkansas, the searchers already there looked haggard and tired. I wondered what I had gotten myself into. I soon found out.
In the swamps of cypress and tupelo, canoeing is about the only reasonable way to get around. When the water is low, this often means dragging the canoe over mud flats and portaging around beaver dams. It's tough work. We quietly paddled along the secondary channels and sat for up to 12 hours per day on small lakes or near other openings in the forest. Our dress code was camo and our attitude was intense.
We were the first team of researchers in more than 60 years to be following up on a confirmed Ivory-billed Woodpecker sighting. We searched from dawn to dusk and developed new strategies in my hotel room each night. With a lot of effort and a good dose of luck, we had a string of three sightings in April 2004 that sent waves of excitement through our group (see the accompanying articles entitled Ivory-bill Encounter, The Return of "Elvis", and A Life-Altering Glimpse).
To round out a very productive month, on April 25, David Luneau, associate professor at the University of Arkansas at Little Rock, shot four seconds of video as the majestic black-and-white woodpecker fled from his approaching canoe.
At the time, we didn't realize how important David's fuzzy video would become. We all expected to get a clear photograph of the bird any day. In the end, David's video played a key role in the Science article which reported that the ivory-bill had been found.
In May, we quickly realized the difficulties of spotting the bird during full leaf-out. The cottonmouths, mosquitoes, and falling water levels weren't helping either. We decided to suspend major search efforts until fall when the conditions would be better. It was during this time that we formed the Big Woods Conservation Partnership (see From Big Woods Partnership to Ivory-bill Recovery) and vowed to keep our work confidential to protect the bird and its habitat from premature publicity.
Meanwhile, a few searchers kept up the effort during the off-season. On June 9, Bobby Harrison got another look at an ivory-bill. On November 9, Marshall Iliff heard 18 double-knocks that he believed were made by an Ivory-billed Woodpecker, based on his extensive experience with other woodpeckers in the same genus, Campephilus.
All of the sightings occurred in a narrow corridor of forest that ultimately connected to vast bottomland hardwood forests in the White River National Wildlife Refuge. Perhaps the bird was breeding or roosting elsewhere and using this corridor as a travel route. We decided to expand our operations, focusing on 550,000 acres that extended south from the area of our initial sightings for about 120 miles.
We established two field stations: one in the north near Cache River in the town of Cotton Plant and one in the south near White River in the town of St. Charles. We found two top-notch field biologists, Elliott Swarthout from the Lab of Ornithology and Peter Wrege from Cornell University, to supervise the search crews, and we recruited Martjan Lammertink, a woodpecker expert from the Netherlands, to advise us on woodpecker biology. Sara Barker Swarthout, project leader of the Lab's Birds in Forested Landscapes project, took on an additional role, helping to coordinate the efforts of 38 volunteer searchers who cycled in and out of the search every few weeks.
We hired 16 young field biologists to serve as the brawn of our search, no small task since we couldn't tell them why they were being hired at first.
From December through April we scoured the Big Woods for ivory-bills and any sign they may have left behind, such as roosting and nesting cavities and trees stripped of bark where the birds may have looked for grubs. We used GPS units to track our movements and assess our coverage, systematically searching 38,500 acres of swamp forest and bottomland hardwood. We canoed and walked grid lines, cataloging 376 potential roosting or nesting cavities, ranking them as A, B, or C based on their suitability for ivory-bills.
Ivory-billed Woodpeckers require large cavities of 4 inches or more in diameter. They are usually quite faithful to their roost cavities, returning to the same hole each night. During evening watches, we monitored 119 of the best cavities to determine if they were being used. We broadcast recordings of kent calls and double-rap display drums and set up life-sized decoys to entice the bird into camera range.
Acoustic monitoring was also a huge part of our search strategy. We used 24 autonomous recording units (ARUs) during 153 2-week deployments (see Listening for Ivory-bills, the High-Tech Way).
Our searchers and volunteers were relentless in their search for ivory-bills. I was thoroughly impressed with their passion and dedication, even in the face of cold, rain, and generally difficult field conditions. In all, we logged about 15,000 person-hours while looking for the ivory-bill.
So, what did we find? On February 14, Lab of Ornithology searcher Casey Taylor heard a series of double-knock display drums for 30 minutes. A short time later, she saw an Ivory-billed Woodpecker fly across an open area as it was being mobbed by American Crows. As the bird flew past, less than 150 yards away, she saw through binoculars the broad white trailing edges to the wings, the long neck with a white stripe going down the side, and a black head with a long bill.
Our five months of continuous seaching that winter and spring also yielded seven other encounters that were intriguing but could not be confirmed. In addition, the ARUs captured some promising audio recordings that are still undergoing analyses (see Hope Knocks).
Although these sightings were exciting, they still left us with little solid evidence to go on. How could we search so hard and find so little? One look from the air at the vast complex of forests in the Cache and White river ecosystems is almost enough to answer the question.
To put things in perspective, imagine trying to find one, or a handful, of birds in a forest the size of Rhode Island! Ivory-bills are thought to occupy a home range of 6-17 square miles and to commute more than 10 miles per day. Finding them is very difficult in the absence of something like a roost hole to orient your search strategy.
So, what's next? The U.S. Fish and Wildlife Service has formed a Species Recovery Team which will explore ways to increase the ivory-bill's population throughout its former range (see From Big Woods Partnership to Ivory-bill Recovery). The Lab of Ornithology, meanwhile, is gearing up for another intensive search in the Big Woods.
In November we'll be leading teams of searchers through the swampy forests once again. We'll check places with suitable cavities and continue to explore new, promising areas throughout the Mississippi Delta. Some new twists to this year's search might include more extensive use of remote cameras, aerial surveys from aircraft, and engagement of volunteers to help increase our coverage.
Ron Rohrbaugh was co-manager of the search for the Ivory-billed Woodpecker in 2004-2005. He is now director of the Lab's Ivory-billed Woodpecker Research Project.
For permission to reprint all or part of this article, please contact Laura Erickson, editor, Cornell Lab of Ornithology, 159 Sapsucker Woods Rd., Ithaca, NY, 14850. Phone: (607) 254-1114. email: email@example.com