SPRING 2002/VOLUME 16, NUMBER 2

Lab director John Fitzpatrick wades through a swamp in search of the ivory-bill. Steve Kelling

At the Lab of Ornithology, our emerging technology for making extended sound recordings in remote places seemed perfectly suited for this difficult quest. Moreover, our historic connection with this majestic bird (see page 2) made us eager to help solve the deepening mystery. In January 2002, with permission from the Louisiana Department of Wildlife (managers of the 30,000-acre Pearl River Wildlife Management Area) and the U.S. Fish and Wildlife Service (managers of the adjacent 35,000-acre Bogue Chitto National Wildlife Refuge), we boated and backpacked our equipment to 12 remote sites in the beautiful bottomland forests of the Pearl River floodplain.

Deployment was no cakewalk. The forest is immense, riddled with deep bayous, and repeatedly flooded wall-to-wall after heavy winter rains. Moreover, each autonomous recording unit, or ARU, is powered by a heavy-duty 12-volt battery to allow 40-50 days of recording. Besides carrying the ARU and its 55-pound battery, each installation demanded that we bring a computer to calibrate and test the system once it was installed. Field logistics were aided immensely by detailed aerial photography supplied by the Louisiana chapter of The Nature Conservancy. Along the route to each site we logged GPS coordinates,

The Lab's search team mounts an autonomous recording unit on a tree in the bayou. Jane Moon Clark

measured tree trunk diameters, and conducted detailed inventories of all woodpeckers we could see or hear. By the end of each day our team was wet to the waist (or in my case, thanks to a misstep near ARU-11, to the ears) and exhausted.

About the size of a quart of milk, each ARU contains a sophisticated system for recording, amplifying, and digitizing sound, filtering unnecessary frequencies (to save disk space), programming daily on-off cycles (no need to record at night), and writing the data to a miniature disk drive. The technology was invented by the Lab's Bioacoustics Research Program to log whale sounds underwater. Now used for studying forest elephants in West Africa and tracking lemurs in Madagascar, ARUs are also great at detecting and monitoring birds. (Besides the woodpecker search, we're using them this spring to study Banded Wrens in Costa Rica and endangered Golden-cheeked Warblers in west Texas.)

Simultaneous with our acoustic search this winter, a team of six excellent field observers was assembled by Louisiana State University's Dr. J. V. Remsen and funded by Zeiss Sports Optics. They spent 30 days in the Pearl River hinterlands searching for the woodpecker by foot, canoe, and pirogue (traditional bayou-country pole boat). We coordinated our efforts with theirs and discussed strategy together during several late evenings after fieldwork.

An autonomous recording unit and battery pack mounted on a tree.

Although the Zeiss team emerged in late February without conclusive evidence, they did make a tape recording of a tantalizing sound - a loud double rap, followed by a series of similar single raps, that closely resembled descriptions of the Ivory-billed Woodpecker's distinctive drum-rap. All attention is now focused on the Lab's acoustic units.

In mid-March we retrieved the ARUs from the Pearl River swamps. As Birdscope goes to press, we are happy to report that every one of the 12 units functioned perfectly, recording 8 hours of sound each day for 32 to 49 days before draining its battery. We are scrutinizing some 4,000 hours or 290 gigabytes of digital sounds, and we'll release our findings in the next issue of Birdscope. Keep your fingers crossed!