These captivating creatures are in trouble, and if their decline continues, Costa Rica's dwindling forests will suffer, too.

by Don Stap

Of the more than 800 species in Costa Rica's marvelous avifauna--the resplendent quetzal included--there cannot be a bird as wonderful, as peculiar, as hauntingly unforgettable as the three-wattled bellbird. Nor one as inextricably linked to the fate of Costa Rica's dwindling forests. 

In the middle of last July I stood in a clearing on the Pacific slope of the Tilarán Mountains in central Costa Rica, listening to bellbirds calling from perches high in the trees: a tin band of piercing whistles; soft, barely audible swishing sounds; and the loud bonk they are named for. The bonk is far from musical--if frogs were bell makers, their bells would sound like this--but when several bellbirds are calling in the same area, as is usually the case here in July and August, when the birds congregate in small remnant tracts of forest below the village of Monteverde, the effect is entrancing. The forest becomes a mountainside of bell towers. 

And what a spectacle! A mature male bellbird, a chestnut-brown bird the size of a grackle, appears to have thrown a snow-white hood over his head and stuck three black leeches--its wattles--on his beak to wave around and enthrall onlookers.  The wattles, normally two to three inches long, can be extended up to five inches; the center wattle can even be erected. From such grand gestures, problems can ensue: One bird has been observed with his center wattle in a knot. When a bellbird is about to make its bonk call, it opens its beak so wide that its lower mandible nearly touches its chest, showing off a mouth as black as a cave. 

A male bellbird calls from a favored perch on a broken-off branch. If an intruder lands on the same branch, the first bird hops over the interloper to get an inside position, then edges him toward the end of the limb. The intruder is driven to the tip of the branch, where he leans out over the end, barely clinging to his last inch of tree. The first bird then leans over, opens his beak, puts it to the second bird's ear, and begins working up what those who know birdcalls say is probably the loudest call in the bird world. The muscles on his neck and upper back swell and contract. His chest heaves. Finally, he lets loose a great bonk that can be heard for more than half a mile. It's enough to knock the intruder off the end of the branch nearly every time, if not dissuade him from the ritual, which is often repeated moments later. 
 
 

SIDEBAR 1 Bird’s-Eye View Name: Three-wattled bellbird  (Procnias tricarunculata) Size: Male, 12 inches long; female, 10 inches Plumage: Adult male: chestnut brown, except for head, neck, and chest, which are white. Adult female: olive-green above; yellow underside striped with dark olive-green  Range: Eastern Honduras to western Panama Nest: Five known nests; twigs placed in vines about 26 feet high Food: Fruits, primarily wild avocado (Lauraceae)

The bellbirds I was listening to had been calling since dawn, and they would continue until nightfall, as they do at least nine months of the year. No one knows why they are so vociferous; the question that day in mid-July was how to stop the rapid population decline that would silence them forever.

Until recently, many Costa Ricans believed bellbirds live all year in the forests around them. But in 1992 George Powell, now a senior conservation scientist with the World Wildlife Fund, began four years of capturing bellbirds, outfitting them with radio transmitters, and tracking their movements. "We were flabbergasted with what we found," Powell says. The bellbirds that breed in the Monteverde Cloud Forest Preserve, on the Atlantic side of the Tilarán Mountains, one of two known major bellbird populations in Costa Rica, make a complex, altitudinal migration. In June, after the breeding season, the birds cross over the continental divide and descend a few hundred feet to the remnant forests on the Pacific slope, where I first heard them last July.  They congregate there for a couple of months and then fly back across the divide, descending to sea level on the Atlantic coast, where they gather in Nicaragua, just over Costa Rica's northern border. A few months later they return to Costa Rica, making a cross-country flight back over the mountains to the Pacific lowlands, and then, two months later, return to Monteverde to breed and begin the cycle once more.

"People thought it was a common bird, but it was the same small population appearing in different areas," says Debra Hamilton, a conservation biologist who is codirector of the bellbird study. Hamilton was netting and banding bellbirds the week I visited Monteverde. Two Costa Rican assistants, Marcony Suarez and Danilo Brenes, had rigged up a system of ropes and pulleys to lower the canopy-level nets quickly--a necessity, given the bellbirds' reaction to being caught in a mist net. When captured, bellbirds appear outraged by the indignity. They screech in protest and must be handled with care. 

Capturing the high-flying, wary bellbirds is easiest in July because nearly all of the males in the population, which is estimated at 700 birds, find their way to two remaining tracts of the forest that once covered the Pacific slope below Monteverde. The tracts, roughly 10 acres each, are on private land, surrounded by coffee and banana plantations and cattle ranches. Although the landowners have supported the bellbird studies, providing access to their farms, one recently began to sell off lots for houses. Disturbing even a portion of one of the remaining tracts could be disastrous for the bellbirds. 

The Monteverde bellbird population has been declining for more than a decade, according to the best evidence available, apparently because of deforestation. (The second major population of three-wattled bellbirds, found in southeastern Costa Rica, might be a bit larger than the Monteverde population. Powell and Hamilton, with the continuing support of the British Embassy, which has funded the project for the past three years, plan to study this second population next year.) Despite Costa Rica's much-praised system of national parks and biological reserves--it protects roughly 12 percent of its land--about half of the country's forests have been cut down since 1940. Moreover, the great majority of what is protected lies in the highlands.  The type of lower montane forest favored by bellbirds falls into the coffee belt, the land best suited for crops. Very little of this forest type remains, and next to nothing is protected. 

If the Monteverde bellbirds are lost, the forests may be irreversibly altered, regardless of efforts to stop deforestation. What attracts the bellbirds to the two isolated remnants where Hamilton was netting birds are the Lauraceae trees, or wild avocados, which at that elevation begin to bear fruit in July. The wild avocado is the bellbird's favorite food. Nearly all of the fruit the bellbirds eat in the Monteverde region is from Lauraceae trees, and studies indicate that roughly 30 percent of the canopy cover in the Monteverde region is made up of trees belonging to the Lauraceae family. The birds depend on the trees, and the trees depend on the bellbirds, which regurgitate the seeds after eating the fruit, in effect planting more Lauraceae trees. This kind of interdependence between fruit-eating birds and fruit-bearing trees is  common, but the three-wattled bellbird, which is unique in so many ways, is also uniquely effective as a seed disperser. 

Daniel Wenny of the Illinois Natural History Survey, who studied the seed dispersal of fruit-bearing trees in Monteverde, concluded that bellbirds are far and away the most effective disperser of Lauraceae seeds: Because bellbirds return again and again to one or more favorite perches, they take the fruit and its seeds away from the parent tree, spreading Lauraceae trees throughout the forest. What's more, since the perches are nearly always broken branches on the edge of treefall gaps or other clearings, sunlight penetrates the forest where the birds drop the seeds, increasing the likelihood that the seeds will germinate by reducing the fungal pathogens that destroy them. 

Consequently, the two 10-acre forest remnants on the Pacific slope may be critical not only to the survival of the Monteverde bellbirds but also to the long-term health of Costa Rican forests. For the past three years Hamilton, trying to keep a close eye on the population, has organized monthly bellbird censuses during the three months of the bird's breeding and post-breeding stages, enlisting the help of the local guides who make their living leading tours through the Monteverde Cloud Forest Reserve.  Fourteen of the guides give up a morning of guiding, a day’s pay, to count bellbirds. At a meeting after the July census, I listened as each guide gave his report. Hamilton added up the figures: 99 birds on the Pacific slope. Last year the count was 127; the year before that it was 153. This may, of course, be a natural fluctuation in the population. 
 
 

SIDEBAR 2 What You Can Do Save the Bellbirds For information about helping to preserve critically important bellbird habitat, contact the U.S. nonprofit Alliance for the Monteverde Institute, through Pennsylvania Audubon, at 717-213-6880 or e-mail grusso@mvinstitute.org.

Over the past two years Hamilton has traveled all through Costa Rica, looking for bellbirds and good bellbird habitat, finding little of the latter. She has asked nearly everyone she has met about the bellbirds--have they seen them, when do they arrive, when do they leave--and she has discovered that most Costa Ricans who know the bellbird are as interested in its well-being as she is. Hamilton also notes that protecting bellbird habitat means protecting forests that are critical to many other endangered species as well, including the resplendent quetzal, the black guan, and the bare-necked umbrella bird. 

Shortly before the census meeting, one of the guides, Samuel Arguedas, gave me a tour of a Lauraceae nursery, part of a reforestation project he has taken charge of. Arguedas, a young man with a winning smile and a passion for the forests that provide him his livelihood, showed me long, neat rows of Lauraceae seedlings growing from soil potted in plastic bags. "These are my babies," he said. Arguedas spoke of how local high school students had helped fill the bags with soil ("The students must learn how important it is to protect the forest") and of his own surprise at discovering that local farmers were interested in planting the trees in their fields. 

At another meeting, the evening before I left, Powell, Hamilton, and others discussed ways to raise enough money to buy one of the farms that contain the remnant forests so vital to the bellbirds. Powell has been through this before. In 1973, on a graduate student's meager income, he purchased land in Monteverde to save it from development, then launched a campaign to raise money to purchase additional land. "It was all done through more than a hundred thousand small donations," Powell said. "We need something like that to happen again." Powell’s efforts are the heart of what is now a complex of reserves in Monteverde that protects 65,500 acres. 

The evening over, I returned to El Sapo Dorado, my hotel, nestled in the mountainside. Its namesake, the golden toad, once lived in the cloudforests of Monteverde. The last golden toad was seen in 1989.