Helping save Yellow-billed Cotinga in Costa Rica

By cartographic standards, Rincon, Costa Rica, barely merits a dot on the map. Its namesake, the Río Rincon, flows quietly past the area’s only building, a sleepy restaurant with a corroded beer sign and two concrete picnic tables hinting at habitation. The restaurant’s parking lot, rock strewn and dusty, was not the kind of place we expected to encounter one of the world’s rarest birds.

Sunrise bleached the horizon as we gathered around Abraham Gallo like iron filings around a magnet. Gallo, a Costa Rican gold miner turned bird guide, had arrived while neighborhood bats were finishing the last of their pre-dawn cartwheels. Yes, he told us with a Spanish accent as thick as over-brewed coffee, he had seen the target bird just prior to sunrise, but it had since departed. Our disappointment was palpable.

Finding a rare species often requires more luck than skill. Many a seasoned tropical biologist has never encountered a jaguar or Harpy Eagle. I had the uneasy feeling finding our must-see bird, notorious for persistent silence, would be akin to searching for an avian needle in a large, tropical haystack.

A week prior, 10 of us swapped parkas for T-shirts as we fled Wisconsin’s snowbound latitudes for a dose of the tropics. Our destination was the Osa Peninsula, a bulge in Costa Rica’s Pacific coast renowned for wildlife. We intended to absorb enough heat, humidity, and exotic birds to last until spring. Not a checklist-driven endeavor, our conservation birding trip was designed to expose us to in-the-trenches conservation.

The Osa, as it is known to locals, is the result of tectonic upheaval. Rising out of the turbulent Pacific, it is tethered to the mainland by an isthmus five kilometers long and three kilometers wide. From the air it resembles a rumpled throw rug: flat along the edges, bunched in the middle. Its quarter-million-acre rainforest, the largest remaining on the Pacific coast of Central America, harbors a frothing pot of species. The peninsula is estimated to support 2.5 percent of the world’s known 1.3 million organisms. Corcovado National Park, crown jewel of Costa Rica’s renowned park system, lays claim to a third of the peninsula and serves as its biological cornerstone. An evolutionary showcase, the entire peninsula is considered a global conservation priority.

Unknown Costa Rica: Birding the Osa Peninsula

The Osa’s interior forests are largely intact, spared conversion to planking and particleboard by unyielding topography. Coastal plain forests have not fared as well, having been systematically whittled to bits and pieces. Patches of forest are sprinkled across pastures that now mostly sprout cows and oil palm, resembling leafy bas-relief in a landscape undergoing transformation.

‘It’s in the scope’

As the sun arced overhead, our attention focused on a surviving scrap of forest kitty-corner from our parking lot assembly. Just across Highway 234, the bituminous thread connecting the Osa to the mainland, a small cluster of trees stood its ground upstream from a new bridge that carried the hustle and bustle of humanity over the Río Rincon’s mocha waters.

Apparently on morning errands, a pair of Cherrie’s Tanagers dashed in and out of the riverside tangle, the male’s scarlet rump patch visible in bright bursts. A pugnacious Great Kiskadee, its breast beacon yellow, issued indignations at a passing rival. Clad in green formalwear, an Amazon Kingfisher balanced atop a bare branch, concentrating on the river below. This sliver of forest, now home to a smattering of common countryside birds, had, as of late, taken on new importance within the conservation community. The reason was perched in the crown of a tall tree.

Gallo deftly rotated his scope in a motion reminiscent of an anti-aircraft gunner from a bygone era. “It’s in the scope,” he announced. “Yellow-billed Cotinga is in the scope.” Eighty feet above the hubbub of civilization, a male Yellow-billed Cotinga surveyed what remained of his diminished domain. We hit avian pay dirt.

Cotingas are a diverse group of fruit-eating birds distributed throughout the New World tropics. Many are well known for extravagant plumage or unique vocalizations. The Yellow-billed is noteworthy for what we don’t know about it, having flown under the conservation community’s radar for years. In 1989, Alexander Skutch and Gary Stiles’ seminal A Guide to the Birds of Costa Rica characterized it as locally common, especially near large stands of mangroves. In 1994, the International Union for the Conservation of Nature (IUCN), a global consortium of the world’s leading scientists, classified the bird as vulnerable to extinction, as did BirdLife’s 1996 version of The World List of Threatened Birds. In 2000, IUCN’s Red List of Threatened Species revised its status to endangered. The accompanying write-up indicated conservation action was needed, and yet the bird received scant attention from the conservation community, less so from birders.

Softball-size, ghost white, and seldom seen, the Yellow-billed Cotinga remains an ornithological enigma. It rarely vocalizes and, when moved to do so, utters an un-avian croak. By all accounts, the bird is declining. The IUCN estimates its population at 150-700 adults spread across at least seven disjunct areas. Virtually nothing is known of its reproductive biology. Only one nest has been found, and Gallo, incidentally, discovered it. Biologists are just now beginning to understand the habitat preferences of this avian apparition.

In 2007, Gallo was part of a small team that initiated a survey of the cotinga’s historical range to assess its status. Based on the effort, we know the species is nearing the tipping point. While never abundant, the regional endemic maintains a tenuous toehold in a handful of shrinking redoubts scattered along the Pacific coast, from central Costa Rica to northwest Panama. None are well protected.

A habitat specialist, the cotinga owes its precarious status to an inordinate fondness for not one but two habitat types — mangroves and adjacent rainforest, or in the parlance of tropical ecologists, pre-montane wet forest. The Yellow-billed is a creature of the ecotone, freely moving between forest types but entirely dependent on both. Nesting and roosting occur in mangroves. When hungry, the birds move landward to feed on rainforest fruit. Lose one forest type or sever their connection, and the future for the Yellow-billed Cotinga takes a decided turn for the worse. Throughout its historic range, forests that once provided safe harbor for the birds have been largely destroyed, the result being the bird’s unfortunate designation as endangered.

Good cotinga karma

The scruffy forest patch where we spotted the bird, it turned out, was vitally important for survival of the local population of Yellow-bills. We got the skinny from biologists with Osa Conservation, the peninsula’s cutting-edge conservation organization and host for our avian adventure. They captured three cotingas, fitted them with transmitters, and chased them over hill and dale for the better part of a year. Their efforts paid off. The Rincon population, as it is known, demonstrated heavy use of this forest remnant. The single radio-tagged female used it every day during a 10-month observation period. Apparently, the parcel has good cotinga karma. Regular use by fellow Yellow-bills was also documented, including a 90-minute period during which 18 individuals dropped by for a visit.

By 10 a.m., bird activity had diminished. We retreated from the parking lot and regrouped in the shade of a stately fig to consider the morning’s encounters. Our outing yielded an impressive bounty, not the least of which was a close encounter with a global rarity. We had arrived filled with anticipation but departed with a nagging a sense of unease. What would become of the Rincon Yellow-bills if this scrap of forest disappeared?

We had spent the better part of the week exploring the Osa’s nooks and crannies, and it was almost time to depart. During our final evening with Osa Conservation staff, we gathered for a farewell barbeque on Playa Piro, a pristine beach more familiar to sea turtles than birders. It was there, against the backdrop of fire-brick sun tumbling into the Pacific, that the future of the Yellow-billed Cotinga took a turn for the better.

Jon Rigden, an affable Wisconsin physician, and his wife, Ann, were newly minted conservation birders. It was their first trip to the tropics, and they were smitten. Roaring howler monkeys, squadrons of macaws, and dancing morpho butterflies conspired to make their Osa experience indelibly delightful.

As the last vestiges of barbeque smoke snaked skyward, Rigden charted a course for cotinga conservation with a simple pronouncement. “Ann and I will provide major support for the purchase of the Rincon remnant if everyone else pitches in.” It was a gesture that would snowball. One thousand miles north, a tiny bird with a far-flung geography also had a role to play.

Every fall legions of migratory birds depart their temperate breeding grounds and funnel into the tropics to escape the rigors of winter. Many travel thousands of miles to reach their ancestral wintering grounds. Regardless of their final destination, all are dependent on the availability of tropical habitats for survival. For some, the future grows increasingly dicey as Latin America’s wild areas fall to the march of “progress.”

A conservation ‘twofer’

Consider the Prothonotary Warbler. The little yellow comet of eastern North America’s floodplain forests is rather finicky about its non-breeding haunts, wintering almost exclusively in Latin America’s diminishing mangroves. Like the cotinga, the fate of the Prothonotary Warbler is inextricably linked to that of mangrove forests. And like the cotinga, the warbler has suffered from the one-two punch of breeding and non-breeding habitat loss but at a hemispheric scale. Its continental population has been steadily declining since the 1960s, resulting in designation as a national conservation priority.

There was widespread realization that protection of the Rincon remnant would constitute a conservation “twofer” by benefitting two declining species whipsawed by habitat loss, one tropical, the other temperate. The opportunity to package habitat protection for a rare endemic and a declining neotropical migrant was catalytic. Within months of that fateful barbeque, an alliance of conservation organizations and like-minded birders coalesced around Rigden’s ocean-side proclamation, enabling Osa Conservation to purchase the remnant and create the world’s first Yellow-billed Cotinga sanctuary.

While much remains to be done for the Yellow-bill, it was an important first step. And equally important, protection of the Rincon remnant serves as a compelling example of the power of birders, motivated purely by their love for birds. Ralph Waldo Emerson said, “Once you make a decision, the universe conspires to make it happen.” For the mangrove ghost, Emerson’s words proved prophetic.

Craig Thompson is the chief of program integration for the Wisconsin Department of Natural Resources Natural Heritage Conservation Program. In our June 2008 issue, he wrote the article “Birdathon of a Lifetime,” about a trip to Ecuador in search of the Jocotoco Antpitta.

View photos of Prothonotary Warbler

View a photo of Jocotoco Antpitta

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Originally Published May 8, 2018