Study Reveals African Hornbill Is Link To Rainforest Regeneration

June 21, 1996

SFSU Saving Rainforests is for the Birds

Merrik Bush (415) 338-1665

SFSU Professors, Students, Say Saving Rainforest is for the Birds
In rare research opportunity, students study Toucan-like birds for clues to African Rainforest Regeneration

SAN FRANCISCO, CA -- After two years of research deep inside a primordial, West African rainforest, a small group of local scientists and students believe they've found an important key to tropical forest regeneration in a large, fruit-eating bird species called the hornbill.

San Francisco State University (SFSU) biology professors Thomas Smith and Tom Parker, with help from a select group of SFSU graduate students, have found a link between the African hornbill's pattern of seed dispersal and the rainforest's ability to regenerate. According to Smith, a Ph.D. in Zoology and associate professor in SFSU's Department of Biology, research shows that unlike mammalian seed dispersers, with their limited range of movement, the hornbill is likely to be critical to regeneration because it flys between the gaps -- or "treeless" areas -- in the forest where other seed dispersers don't travel, distributing seeds as it goes.

"Monkeys and elephants aren't good at moving across gaps in the forest," says Smith, "so the hornbills are a very important first stage of forest regeneration, particularly in regions which have been cleared."

By studying the hornbill's seasonal shifts in diet and size, their nesting habits, and home ranges, his team can estimate how much habitat is needed to maintain normal forest dynamics and natural forest regeneration.

Smith, who has a history of breaking new ground in avian research, says that since every rainforest is ecologically unique, scientists must examine species diversity within each tropical forest system to determine the best conservation strategy. Although species of the Asian hornbill have been studied more extensively, this is a first for their West African cousins.

"We're studying the hornbill because we believe it is a crucial element of this ecosystem, and until now, not much has been known about it." By maintaining the hornbill's habitat, such as nesting requirements, Smith says conservationists have a better chance of preserving these rapidly deteriorating rainforests.

The research team's field station, located 18 miles inside the Dja Reserve -- a lush rainforest in Cameroon -- is in one of the most remote regions in West Africa. Because the forest canopy is so dense and the undergrowth foliage thick, Smith and his students depend on the local natives, the Baka people, to help navigate the forest.

"They're amazing," says Smith, "they walk into the forest and know every sound, plant, tree and animal in the region. They've also taught us to enjoy the local food." Don Stauffer, an SFSU graduate student studying the breeding habits of the hornbill, has spent the last year sampling the Baka menu. "I've eaten viper as thick around as a man's thigh," he said. "It was delicious."

The Baka, a shy people once referred to as "pygmies" because they rarely grow taller than five feet in height, were introduced to the world via a National Geographic documentary called "The People of the Forest." Keeping a temporary encampment next to Smith's own field station, a small group of these Baka men work with the SFSU team.

By radio-collaring the birds and looking at how they move around, the research group can determine the range and pattern of seed dispersal, and locate and map their nests. But the hornbill, although conspicuous with its thick, "knobby," 6-inch-long down-curved bill and "noisy," loud call, isn't easy to locate when nesting. Before the project began, only one nest had been discovered by scientists in 1930. Stauffer, who located 40 nests during his yearlong stay, says the reason is twofold.

"The birds build their nests in already existing holes in the trees which are sometimes 60 feet up the trunk, so they're not easy to see," says Stauffer. "Also, for four months out of the year the female seals herself into this cavity by packing mud around the opening, leaving only a slit large enough to receive food for herself and her one chick," he says. "In order to find the nests I have to watch the males carefully and look for particular behavior to determine if a nest is in the area."

Both Smith and Stauffer emphasize the importance of knowing the nesting habits of the hornbills. "One thing that often limits populations of cavity-nesting birds, is -- not surprisingly -- available cavities," says Smith. "Studies show that you can increase population densities by providing artificial nest boxes. So in areas that have been devastated by logging, there is the possibility of providing nest boxes to increase hornbill populations and reseed forests quicker."

Stauffer says he is eager to return to the Dja Reserve. "The privilege to work in such a pristine environment is unparalleled. Because of the scope of this project, it gives me a leg up on further graduate and Ph.D. work. It's really, a tremendous opportunity."

The study, started in 1993, received initial funding totaling $86,000 fromthe New York Zoological Society, the Wildlife Conservation Society and student fellowships from the National Science Foundation . ECOFAC, a European conservation organization with projects in seven other West African countries, is sponsoring further research at Dja, says Smith, who is expanding the study into forest areas targeted for logging. "We are breaking important new ground," says Smith. "There's much more area to cover."

Contact: Ligeia Polidora
EDITOR'S NOTE: Location photography available upon request.

San Francisco State University

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