Ivory-bill Evidence Reported from Florida

By Pat Leonard
September 2006

The Ivory-billed Woodpecker is playing hide-and-seek again. Avian biologist Geoffrey Hill of Auburn University in Alabama says his team has collected sound recordings and sight records that show ivory-bills may inhabit the Florida panhandle in the Choctawhatchee River basin. The findings were published Tuesday, September 26, in the journal Avian Conservation and Ecology.

Geoffrey Hill in Florida

“We’re not claiming proof of ivory-bills,” cautions Hill. “We’re building this all on supposition from a data set and putting all our data out there.” Nearly all the evidence collected in Florida is now public on web sites established by Auburn University and the University of Windsor in Ontario, where the acoustic work is being done. The data include sound recordings, charts, notes, drawings made in the field, and photos of cavities, feeding sign, and  habitat. The search yielded no photos of the bird, as frustrating for the Florida team as it has been for crews in Arkansas. “We don’t have any good pictures,” Hill says. “It drove us crazy. Without finding an active roost or nest hole, getting a picture of these birds is really tough.”

Cornell Lab of Ornithology director John Fitzpatrick says the Florida announcement is a terrific boost. “I think it illustrates the urgent need for a long-overdue, coordinated, comprehensive, range-wide search, using modern techniques, using significant human energy and investment—from Texas and Arkansas up across to the Carolinas. This is the time to pull out all the stops. I think the Florida announcement renews the resolve of the birding and conservation communities at large to get out there and do the search that’s required.”

Catching Ivory-bill Fever

Florida swamp forest, photo by Paul Mennill

The Florida search was prompted by the April 2005 announcement from the Cornell Lab of Ornithology and partners that at least one ivory-bill had been documented in eastern Arkansas. Hill recalled having received a report of an ivory-bill in Geneva County, Alabama, about 10 years ago. In late May 2005 he decided to take a weekend trip to the Pea River area accompanied by Brian Rolek and Tyler Hicks, two field technicians working for him over the summer. They were disappointed at finding unsuitable habitat and on the spur of the moment decided to head farther south into Florida.

Without even a detailed map of the area, they picked a boat launch along the Choctawhatchee River purely at random and went there the next day. Less than an hour later, Hill says, “We heard something banging in a really solid manner on a tree, up above us in the canopy. We couldn’t see it—all we could hear was this loud banging, loud hammering.” As they moved around to see what was making the noise, a bird took off. Only Rolek saw it, and described white trailing edges on the upper side and underside of black wings, classic ivory-bill plumage. The date: May 21, 2005. Later that morning, Hill says he heard a double knock. The following weekend Hill and Hicks returned to the site. “Tyler got a clear look at a female ivory-bill through his binoculars, flying through the forest,” Hill says. “And when Tyler got a clear look—Tyler’s the best field ornithologist I’ve ever been out with—I would trust his sightings better than anybody in North America.”

Collecting More Data

Dan Mennill watches for ivory-bills, photo by Paul Mennill

On the heels of those first encounters, Hill decided to do a follow-up search to collect physical evidence. He enlisted Dan Mennill at the University of Windsor in Ontario, Canada, an expert in sound recording and analysis. Mennill was assisted by one of his graduate students, Kyle Swisten. These five made up the core team that would secretly work the Florida site from December 2005 through April 2006. Brian Rolek and Kyle Swisten actually lived in the swamp. Tyler Hicks would return during breaks from his studies at Western State College in Colorado. Hill spent two or three weekends a month at the site. Mennill spent most of his time working with his sound analysis team in Ontario. Brian Rolek conducted the bulk of the field work alone, occasionally assisted by a few volunteers while Swisten maintained the recording stations.

The study site covers about two square miles, most of which is owned by the state of Florida. The team set up seven “listening stations” using recording devices created by Mennill, a former post-doctoral researcher with the Lab of Ornithology’s Bioacoustics Research Program. He says, “I wanted to design

University of Windsor sound analysis lab, photo by Dan Mennill

something that would record at every daylight hour. It’s a fairly straightforward approach, using a highly sensitive, omnidirectional microphone connected to a digital recorder that is capable of recording for 24 hours at a time once you hook it up to a little motorcycle battery.” Mennill’s ornithology students at the University of Windsor scanned 11,419 hours of recordings. They compared spectrograms downloaded from the listening stations to known recordings of Pale-billed Woodpeckers, gunshots, and other sounds. There are no known recordings of Ivory-billed Woodpecker double knocks, but Pale-billed Woodpeckers are in the same genus, Campephilus, and also make a double-knock sound.

Releasing the Evidence

The Florida search wrapped up at the end of April 2006. The final tally: 13 sightings by 4 individuals, including two occasions when observers saw a pair of birds. Hill says the sound analysis turned up 210 kent-like calls the team considers “really convincing,” and 99 double knocks, all made in the same two-square-mile area, sometimes multiple calls and knocks on the same day. The team also has a couple of sound recordings that indicate two birds may have been present. Some of those recordings include sounds that do not match those made by any other species, or even the ivory-bill recordings made by Arthur Allen during the 1935 Cornell expedition to Louisiana.

The double knocks are also intriguing, but as the Lab’s acoustic experts found, it’s nearly impossible to say conclusively that they were made by an ivory-bill because similar-sounding double knocks can also be attributed to other sources, such as the flapping of duck wings. One can only say whether the sounds are consistent with the ivory-bill’s drumming pattern. The range of variation in ivory-bill sounds is also unknown, since the only recordings come from one pair of birds during the Allen expedition.

One of many interesting cavities, photo by Paul Mennill

The Florida crew found 20 cavities they say might have been made by an ivory-bill. Fitzpatrick thinks the cavity data are some of the most interesting: “I’m most excited about the fact that they have woodpecker cavity holes, several of which appear to be reasonably fresh and are bigger than the excavations typically made by Pileated Woodpeckers. There’s nothing else that would be digging those except a larger woodpecker. The cavities are the right shape and size and they’re placed in the right spots,” Fitzpatrick says.

Expanding the Search

What next? Hill says, “We feel like we’ve got a body of evidence that warrants an expanded search this year. Skeptics will say, ‘How could you have repeated sightings of the bird and not get a picture?’ My excuse is we had insufficient personnel and insufficient equipment.”

Mennill agrees, “I think one of the most exciting things about our search is that everyone who spent a substantial amount of time in the field is having repeated encounters. All of this is suggesting to me that we just need more eyes, ears, and listening stations out there before we’re really going to get the evidence that takes us over the top.”

Hill says enough funds have been committed by the federal government and the state of Florida to expand the search to a six-square mile area. The plan is to have each searcher assigned to an area of less than one square mile. They’re hoping to hire professional technicians to work full-time for four months on a little money ($1,200 a month) and a lot of enthusiasm. Access is not being restricted but the search team hopes birders will stay out of their study site and cooperate if asked to leave. The Cornell Lab of Ornithology will provide some equipment and personnel for the Florida search.

Mennill’s goal is a 24-hour turnaround on the acoustic data for the coming season. “We’ll get on a high-speed modem and upload the sound to my sound analysis lab here. The students will scan the sounds the next morning, and then we’ll be back on the horn to the field team saying ‘Here’s where we detected a bird.’ In that way we’re going to use this bioacoustic approach to help us not only study the bird’s vocal behavior and its movement behavior but to try to get the photograph as well.”

It all bodes well for the overall goal of protecting the Ivory-billed Woodpecker and restoring its bottomland forest habitat. Fitzpatrick says of the upcoming field season: “The Cornell Lab of Ornithology is poised to work as a cooperative partner in the range-wide search for the ivory-bill. We’re hoping we can help play a role in the success of the Florida team, as well as that of any of the other local searches that may request our help.”

As for finding more ivory-bills in Florida and in other states where searches will be taking place, Mennill says, “Wouldn’t that be wonderful? You know we got a spark of hope from Arkansas—we’ve got another spark now from Florida and so maybe this will start a fire all across the American South.”