The study began with researchers trapping six species of tropical birds in mist nets and equipping them with radio transmitters, so that they could follow individual birds' movements.
Before that, however, researchers fed the birds seeds from native plants and monitored their digestive habits, using the data to build statistical models that, combined with information from the radio transmitters, let them estimate how far the birds flew before dropping seeds.
Researchers were surprised to learn that only one of the six species, Turdus albicollis the largest of the birds they studied actually ingested the seeds. That species also flew farther than any of the other birds.
"A lot of ecology has focused on the movement of birds," said Maria Uriarte, a professor in ecology, evolution and environmental biology at Columbia University, and the paper's lead author. "We found that it's all about the big birds and where they like to be."
The other birds would eat, fly to a nearby tree branch, chew the seed for a bit and usually spit it out.
The seed in question belonged to a plant called Heliconia acuminata. The scientists chose it because it grows low to the ground, is easy to work with and easily identified. The plant has no common name, but casual observers would probably liken it to a Bird of Paradise, he said.
If the Heliconia acuminata's seed is dropped by a bird between forest fragments, he said, the seed more than likely will bake in the heat, and no plant will grow. Long-distance dispersal is critical for plants to establish new populations.
The take-home message for scientists and conservationists is that if forest fragments are so far apart that the animals and plant
|Contact: Emilio Bruna|
University of Florida