No sign marks the start of the trail to one of the last unspoiled habitats in all of Africa. I wouldn’t see it anyway. I’m crammed into an 11-passenger van carrying 13 people and a heap of backpacks as it navigates to that unmarked spot in a scientific reserve that sprawls across the southern end of Bioko, a mountainous tropical island 20 miles off the west coast of central Africa. A sweaty forearm is smashed against my sweaty shoulder. Three knees dig into my back through the thin seat. I’m not complaining—the porters behind me will lug our expedition’s gear for two days over 18 rugged miles into the Gran Caldera de Luba, a rainforest-blanketed volcanic crater whose 7,400-foot-high walls create a natural sanctuary for a dazzling array of wildlife. The few dozen people who make the arduous journey each year come mostly to survey monkeys. Our group is venturing into this primeval realm to document its far-lesser-known inhabitants, especially birds.

If we’re really, really lucky, I’m told, we’ll spot the near-mythical Grey-necked Picathartes, a bird whose global population might number as few as 3,500 individuals. If we’re insanely lucky, we’ll discover a new species.

Just outside Ureca, the only village on Bioko’s south coast, our driver stops on the brand-new road that bisects the 200-square-mile Gran Caldera de Luba Scientific Reserve. Sandal-clad porters scramble out, heft overstuffed backpacks, and disappear into the forest. The rest of us—me, four scientists, an Equatoguinean college student, and a photographer—slip on daypacks and follow two guides on a zigzagging eight-mile route through dense forest and along black-sand beach to Moraka, a field camp where a half-dozen volunteers monitor primates and nesting sea turtles each winter, and where we’ll crash tonight. The forest trail is dotted with spent shotgun shells from bushmeat poachers who hunt monkeys, small antelope called duikers, and large birds such as Black-casqued Hornbills. Hunting is illegal in protected areas like this, but there’s scant manpower to enforce the bans. To get where hunters don’t go, a guide tells me, you need to suffer.

I understand what he means the next day as we gasp up the crater’s flank. The only sign of humans is the root-tangled trail leading 10 grueling miles up 4,000 feet in elevation gain. Equatoguineans, it seems, don’t believe in switchbacks. At our midway break, Luke L. Powell, 34, a conservation ecologist at the Smithsonian Migratory Bird Center, barely seems winded; he’d popped a caffeine pill. Jacob C. Cooper, 24, a University of Kansas master’s student who recently modeled the range and distribution of nearly every hummingbird species in the world, has binoculars to his eyes and is calling out bird species. I can’t follow a word. (He’s speaking fast. In Latin.) Next to me, cursing his smoking habit, is Jared Wolfe, 35, a research ecologist with the U.S. Forest Service who studies the effects of climate change on birds. His fiancée (and the group’s mammal expert), Kristin Brzeski, 32, a conservation geneticist who studies coyotes at Princeton University, is doing yogic stretches.

The sheer walls of the caldera create a haven for wildlife, protecting birds and mammals from hunting and deforestation. Photo: Tristan Spinski

It’s the crew’s first trip to the caldera, and Brzeski’s first year with the Biodiversity Initiative. The guys founded the group in 2013 to explore the understudied birdlife in Equatorial Guinea, a country that is home to precisely zero professional ornithologists. So far their annual expeditions on Bioko and the sliver of mainland between Cameroon and Gabon have added 11 names to the country’s avian list of roughly 400 species. They expect to turn up dozens more. They also aim to help boost conservation in this rapidly changing country, where oil riches are fueling booming development.

So far the annual expeditions on Bioko and the sliver of mainland between Cameroon and Gabon have added 11 names to the country’s avian list of roughly 400 species. They expect to turn up dozens more.

At last we crest the ridge, then drop down the vertiginous inner wall, grasping poles driven into the ground. At the bottom lies our last obstacle: the Ole River. The water traces an old lava flow, shooting out of the crater in a dramatic 75-foot waterfall and tumbling down to the ocean far below. It’s January, height of the dry season, so we boulder-hop across the thigh-high water to Hormigas Camp. From April through October, when there’s more than 30 feet of rain, the river swells immensely, blocking human access for most of the rainy season.

We use the last hour of sunlight to search for the legendary picathartes. Wolfe machetes a path to the waterfall, and six of us squeeze onto a dining-table–size basalt outcrop, peering through binoculars across the 40-foot-wide abyss to the sheer rock wall beyond, where a primatologist saw the birds nesting last March.

“How do their young fledge?” marvels Wolfe.

“Faith?” Powell says.

The picathartes is largely a mystery. The bird is slender and gray with a vermilion cap, and walks in near-silence, hunting insects in the forests of Equatorial Guinea, Cameroon, Nigeria, and Gabon. When it does vocalize, it makes an un-birdy hiss, cough, or “yap of a Pekinese,” as one observer described it. We hear grumpily squawking African Grey Parrots and chattering red colobus monkeys. Nothing pica-esque.

For eight days we’ll explore this primordial place. Brzeski will deploy an army of motion-activated camera traps to document elusive wildlife. The crew will travel deep into the crater in search of birds, and be the first people to band in the caldera in a quarter-century. Such promise of discovery eases the disappointment of not seeing the picathartes tonight. “That would’ve been too easy,” says Powell. “We’ve got all week.”

Equatorial Guinea is the kind of place biologists go gaga over. Its mainland jungles boast rare animals like picathartes, chimpanzees, elephants, and gorillas. Bioko is even more intriguing. Islands aren’t usually flush with primates or forest birds, which are unlikely to cross open waters and colonize new shores. Bioko, however, was part of the mainland until 12,000 years ago, when rising sea levels cut off what had been a peninsula. It’s an ark whose residents have evolved completely isolated from their counterparts on the mainland. Today at least two of the island’s birds—Fernando Po Batis and Fernando Po Speirops—are found only here, and some of its three dozen or so avian subspecies may well be unique species worthy of protection.

Despite its allure, the country’s birdlife remains remarkably understudied. Ornithologists had barely begun systematic surveys when Equatorial Guinea achieved independence from Spain in 1968. Turmoil ensued—school closures, infrastructure decay, economic collapse, and a 1979 coup d’état that put Teodoro Obiang Nguema Mbasogo in power—halting ecological research for two decades. The 1990s saw greater political stability, and researchers began returning. Oil companies came then, too, after vast offshore reserves were discovered. This past April President Obiang was reelected to his sixth seven-year term, besting six opponents with an eyebrow-raising 94 percent of the vote. His reign secured, he’s pushing on with his petrodollar-fueled plans to massively expand infrastructure. Most ambitious is Oyala, the new capital rising out of the rainforest on the mainland; unlike Malabo, the current capital, which is on Bioko, it’s safe from seaborne coup attempts, like one in 2009. Now, with oil production waning, Obiang is looking to build up other industries, including ecotourism.

Currently, a visitor’s best, perhaps only, bet for getting into this wilderness is through the Bioko Biodiversity Protection Program, the country’s oldest conservation organization. When American conservation biologist Gail Hearn first visited in 1990, Bioko’s monkeys blew her away, leading her to establish the BBPP in 1998. Now a joint venture of Drexel University in Philadelphia and the National University of Equatorial Guinea, it’s one of the few green groups here. It studies the island’s biodiversity, and its long-term research documents bushmeat consumption and tracks primates and marine turtles in the Luba Crater Scientific Reserve. The camps we inhabit during our expedition, the trails we follow, the guides and porters we hire, the entry permit, are all thanks to the BBPP.

From left: Amancio Motove Etingüe bands a Forest Robin in the caldera; Maximiliano Fero, whose students at the national university, including Motove, have taken courses that the Biodiversity Initiative teaches each January at the Moka Wildlife Center; a dead leaf collected in the caldera; Asunción Ripeu Toraó banded a sunbird during this year’s tutorial. Photos: Tristan Spinski

Nobody took up birds with the same dedication. The most extensive avian investigation to date took place on Bioko and the mainland over 100 days from 1989 to 1992. UCLA tropical-forest bird expert Tom Smith sampled the caldera’s flank on another expedition, in June 1996; drenched conditions made it impossible to enter the crater itself. The efforts that followed were sporadic, aside from one ongoing project: Since 2011 the BBPP has regularly netted birds at the Moka Wildlife Center, the country’s only field station.

That haphazard history makes the Biodiversity Initiative’s plan to return annually incredibly valuable, says Drew Cronin, a BBPP primatologist who oversees the group’s bird surveys. “We don’t have nearly the expertise they do,” he says. “Jacob is like a bird Rain Man. Jared is a molt expert—he can age birds by their feathers. And Luke has great general bird knowledge. They’re inherently going to be able to document more species.

“The bottom line,” Cronin continues, “is the more we can understand what’s there, the more leverage we have to protect it.” Time is short, and not just because of development. Climate models forecast that temperatures will rise drastically in Africa. “Everything is getting mixed up, and we really don’t know what the ecological impacts will be,” Smith says. “The more people pushing for conservation, the better.”

It was Cooper who first mentioned going to Equatorial Guinea. Three years ago, when he was an undergraduate at Louisiana State University studying ornithology and Powell was a grad student there, they pitched in for two weeks on an American Redstart project near Jamaica’s remote Cockpit Country. Although it was Cooper’s first visit, while out birding he’d count many more birds than Powell, who’d done Yellow Warbler research there. Cooper had crammed before the trip, memorizing species and their songs, and studied in-country at night. “This guy’s legit,” Powell recalls thinking. One evening, looking over the unspoiled habitat, the two mused about bird surveys in other little-known places. Cooper, who manages the eBird checklist for Central Africa, approving entries to the online avian database, mentioned that Equatorial Guinea had zero entries. Back home, Powell’s research confirmed the paucity of avian information and revealed that Equatoguineans speak Spanish, which he speaks fluently. “I was like, well, shit, we have to go.”

He recruited Wolfe, an LSU grad student and the founder of the Louisiana Bird Observatory, where Cooper volunteered. “He’s a great ornithologist,” Powell says of Wolfe. “And I needed more support than Jacob, who was just so green.”

The trio self-funded the first trip to the tune of $4,000. They’ve since raised roughly $15,000 a year through a National Geographic grant, private donations, and a Kickstarter campaign—enough to keep coming back. “There’s so much to discover, practically everywhere you look,” says Wolfe.

From the patio of the BBPP office in Malabo, Cooper spotted Ethiopian Swallows zipping about. A new species recorded for Bioko, hiding in plain sight.

From Left: The white spots and red eye indicate that this Grey-headed Negrita is an adult; the shy Forest Robin is more often heard than seen; the Olive Sunbird resembles a hummingbird, but it perches, rather than hovers, when consuming nectar; this Green Twinspot’s bright-red facial feathers identify it as a male; the Mountain Sawwing, a member of the swallow family; Green Twinspot, a ground-feeding bird. Photo collage: Tristan Spinski

Our first morning at Hormigas (“ants,” in Spanish) we swig instant coffee and devour rice and Spam that the cook, Apolonio, reheats on the fire. The conversation revolves around vivid dreams induced by malaria meds. That, and hyraxes. The rabbit-size, nocturnal mammals have an earsplitting territorial call that begins as insistent shrieks and grows to a desperate pitch. They scream for hours.

Powell breaks in. It’s time to split into two groups and go birding.

“Yes,” Wolfe agrees. “I’ll take Jacob.”

“No way,” says Powell. “We’ll flip for him.”

They know Cooper will tally the most birds. Wolfe grumbles good-naturedly when he loses the toss. He, Brzeski, and guide Cirilo head north. I go south with Powell, Cooper, and Amancio Motove Etingüe, a student at the National University of Equatorial Guinea. Our guide, Miguel, is from Ureca. He strolls noiselessly, hands behind him, pausing to point out duikers bounding through tangled undergrowth and monkeys in treetops. He stops me from stepping on bratwurst-size turds of drills, highly endangered primates we haven’t seen yet. We mark the spot for Brzeski.

We move slowly, looking, listening. Cooper, audio recorder running, notes a heated exchange between two Chestnut Wattle-eyes, plump, flycatcher-like birds. African Grey Parrots, abundant on Bioko but dwindling nearly everywhere else due to the pet trade and deforestation, gab in the canopy. A Hadada Ibis floats overhead. Somewhere a Chocolate-backed Kingfisher calls mournfully; the best regional guidebook says it occurs only at far lower elevations. We step over a column of vicious driver ants that may have attracted the insectivorous Velvet-mantled Drongo, whose unmistakable grating electronic sound cuts through the ubiquitous chups and whistles of the Little Greenbul.

An unfamiliar song sends Cooper and Powell searching for the vocalist. It’s reddish, with a short bill: a Rufous Flycatcher-Thrush.

Cooper shakes his head. “It sounds really weird.”

“Different subspecies?”

Cooper shrugs. “It could just be an alternate song I’m not familiar with. I need to do more research.”

In all, the two teams detect about three dozen species. “It’s not very birdy,” says Powell. Maybe, Wolfe says, the habitat is lacking, or the primates could be keeping the bird numbers down. A discussion ensues about comparing the primate-rich caldera to a topographically similar area with rampant poaching. It’s the fifth potential research project I’ve heard about since breakfast, and banding hasn’t even begun.

That afternoon we set up 20 39-foot-long mist nets suspended between saplings the guides had expertly macheted. Two more nets go near the picathartes ledge.

The nets open at first light. Wolfe fumbles the first capture, a Forest Robin that escapes into the trees. “Jared is one of the best banders in the U.S.,” says Brzeski, “but he needs his coffee.”

Cooper helps untangle birds; once the nets are clear, he’ll conduct an audiovisual survey, counting far more birds than the nets snag. He places the captives in cotton bags and delivers them to the banding station. Motove, the novice, removes a Forest Robin from a bag. Under Wolfe’s patient guidance, he attaches a numbered aluminum leg band, calls out species name, age, sex, wing and tail length, molt condition, and fat presence, which Brzeski records; over time, recaptures reveal critical information about the survival of bird populations. Next, Powell collects blood and a feather for an avian malaria study and genetic analysis. Any bags with guano smears will go to a researcher in the United Kingdom, who will determine the birds’ diets.

Cooper may use some of this data for his Ph.D. project on mountain-dwelling birds in Cameroon and Equatorial Guinea, comparing the birds’ genetics and songs. Differences could indicate that a subspecies has diverged into a distinct species.

Motove processes a bird every 20 minutes or so. Wolfe watches carefully for signs of stress—yawning beak, drooping head or eyelids—ready to intervene if necessary. It never is. I ask Wolfe how long one bird takes him. “Maybe a minute or two?” Later, when dark clouds gather and a few fat raindrops fall, Wolfe jumps in so they can release the birds before it pours. I time him: 58 seconds flat.

Around 11 a.m., as banding is wrapping up, Wolfe goes to check the picathartes nets. An hour later he’s back. “Guys, I think I heard it!” Finding empty nets, he scrambled below the waterfall, where he flushed something in the thick vegetation and heard a coughing noise. He’s sure it was a pica. As we pack up that afternoon to go to North Camp for three days, Powell laments moving four miles from the caldera’s only known nesting site. Brzeski sets up a video camera on the ledge. Don’t get your hopes up, she tells me. At that distance, any animal across the 40-foot expanse will likely be an unidentifiable blur.

A mile out of camp, I’m sorely missing the porters. And chiding myself for not adding weights to my training hikes.

I forget my discomfort when we see the monkey skeleton. Brzeski and Wolfe are flabbergasted. They were here yesterday on their Cooper-less hike; it wasn’t. Maybe they somehow missed it. Or perhaps it died yesterday afternoon and driver ants picked it clean overnight. It’s unsettlingly plausible. The tiny carnivores are known for stripping prey to the bone.

Cooper has wandered away from the macabre scene. He’s eyeing the canopy, recorder held aloft. “What the . . .” he mutters, then whistles: whew whew whew whew whoo whoo. Listening for birds is something he can’t shut off. On his second date with his now-wife, she was baffled when he suddenly grabbed her and, instead of kissing her, said, “Do you hear that?” then ran off to find a hooting Great Horned Owl. Now he calls to the photographer: “Tristan. Camera. Now.” The command pulls everyone but Brzeski away from the skeleton to look for the mystery bird.

We pish and vie for a look at the bird darting about. Finally, Wolfe locks onto it with his binoculars.

“Okay, I think it’s a longbill,” he says.

“A longbill?” Cooper is incredulous. “It sounds wrong.”

“Well, gray head, yellow eye, longish bill, yellow body.”

“That perfectly describes a Yellow Longbill,” Cooper agrees. “On the mainland it goes tick tick tick tick tick tick.”

“Does that song jibe?” asks Wolfe.

“No,” says Cooper, again whistling whew whew whew whew whoo whoo. The tiny bird replies. “I have never heard that before.”

He’ll review the recording later, and possibly add Bioko’s Yellow Longbill to the list of caldera birds that warrant investigation as distinct species.

Our surroundings grow increasingly wild. “It’s like the Land of the Lost,” says Cooper. The limbs of moss-covered trees drip with vines and orchids. We wade through towering grasses. Ominous black millipedes and cheery fuzzy caterpillars inch along super-size ferns. Butterflies in a kaleidoscope of colors flit about. Dozens of saucer-size orb weavers with hairy red legs and bulky black bodies hang overhead; each spider's web stretches 10 feet or more between trees, swelling and shifting like a kite in the wind. Monkey troops berate us every 15 minutes or so. We keep moving, until we hear deep woofs. Drills! Hunting has wiped out these baboon-like monkeys from nearly all but the island’s most remote southern reaches. We’ve been looking for them for days. Now five are in a tree 20 feet from us. It’s exhilarating. And intimidating. The alpha male—apparent from his vibrant red and violet genitals—must weigh 60 pounds. They watch us for several minutes, then nonchalantly move away.

The beaches of southern Bioko are nesting grounds for four species of sea turtle, whose eggs and meat are a sought-after food source for locals. Photo: Tristan Spinski

At North Camp, Apolonio is preparing our Spam-and-pasta dinner over the stone-ring fire pit. We claim level-ish places to pitch tents, and bathe in the stream at the edge of camp. “This is so plush,” Wolfe says.

This crew is familiar with the hardships of fieldwork. They’ve picked hundreds of ticks off each other, nursed one another through injuries and ferocious bouts of vomiting and diarrhea. They’ve subsisted on rodent gravy and rice made by Wolfe (trail name “Cook-y”). On their first Equatorial Guinea expedition, before the road was completed, the guys hiked from Ureca to the Moka field station. They immediately ditched their banding plans. The blackflies and mosquitoes were relentless. It poured nonstop, transforming the rugged hunting trail into a miserable mud slick. Cooper started out sick, then became violently ill from an allergic reaction to the duct tape he’d used to cover painful blisters on his feet. Powell and Wolfe split his 50-pound load. By day three they were nearly out of food and so thirsty they drank iodine-treated puddles. “We were disgusting, exhausted, delirious,” says Wolfe. “It felt like we reached Moka just in time.”

Our trip hasn’t been entirely without mishaps. Powell and Cooper suffer stomach cramps after drinking water from a former diesel container. A deadly Jameson’s mamba slithers into the kitchen one evening and rears up, but doesn’t strike. The Hormigas toilet—a tarp-covered pit—is home to snakes, bats, spiders, and swarms of bees. Nearly everyone experiences some combination of bee stings at the latrine, caterpillar rashes, and ant bites; Cooper gets the worst of it when ants invade his tent one night through an imperfectly closed zipper. Another night a millions-strong army of ants swarms the ground behind the kitchen benches during dinner. In a flash the guides douse the area with gas and light a match. The huge swoosh and wall of flame send us scrambling back in giddy terror. Cirilo assures us the ants won’t cross the fire line. We’re safe, he says.

Another night a millions-strong army of ants swarms the ground behind the kitchen benches during dinner. In a flash the guides douse the area with gas and light a match. The huge swoosh and wall of flame send us scrambling back in giddy terror.

Over the next two days, Brzeski sets up camera traps and everyone else settles into banding. Motove handles birds with greater confidence, from petite hummingbird-like Olive Sunbirds to a hearty Grey-headed Negrita, a black finch whose red irises indicate it’s an adult male. He cuts his processing time in half. “It’s like one pop quiz after another,” he says.

Before traveling to the caldera, the team conducted a two-day session on banding and mammal surveys for 16 students from the national university. It’s the third year they’ve taught the course, where they met Motove last year. “There aren’t a lot of people here who study ecology, forestry, or biology,” says Maximiliano Fero, a botanist and the research chair at the university, and the person who issues biological sample export permits for the Biodiversity Initiative. “Little by little it’s growing, but that’s why collaborations with international partners like the Biodiversity Initiative are so desirable.”

On paper, a quarter of Equatorial Guinea is protected, but poaching and illicit logging are rampant. The country’s protected-areas agency, INDEFOR-AP, is motivated to do biological surveys and crack down on illegal activity, the BBPP’S Cronin says, “but they have a shoestring budget and little political support.”

Bushmeat is a major conservation threat. It’s a staple here, sold at a huge Malabo market and roadside stands. The BBPP has tracked bushmeat sales, a proxy for hunting levels, for nearly two decades. Last year Cronin and colleagues reported that from 1997 to 2010, Malabo market surveyors counted more than 35,000 monkeys (illegal to kill since 2007), nearly 59,000 duikers, some 81,000 rodents, and more than 4,100 birds, including Black-casqued Hornbills, Great Blue Turacos, and Palm-nut Vultures. Sales have increased over time, tracking economic prosperity.

Deforestation is the other main danger to wildlife. “The rate of deforestation in Equatorial Guinea is at an all-time high,” says Katy Gonder, the BBPP’s director. That’s largely due to clearing land for Oyala, the new capital, though logging occurs in reserves throughout the country, as Biodiversity Initiative members have seen firsthand. While out with two INDEFOR-AP employees, touring a protected area on the mainland, they came across “huge dudes with huge muscles ripping boards with chainsaws in the middle of the forest,” as Wolfe recalls it. The operation had obviously been running for some time. The supervisor spouted veiled threats, then tried bribes, before finally agreeing to shut down. The feds confiscated five chainsaws, and the company was ultimately fined, says Wolfe.

This year the Biodiversity Initiative provided two field techs with gear and training to band birds in two 100-hectare plots outside Oyala—one logged, the other untouched. The project lays the groundwork for a long-term study on how disturbance affects birds and mammals.

A $50,000 U.S. Fish and Wildlife Service grant the Biodiversity Initiative has applied for would go toward expanding operations next year, training more students and federal scientists. Having locals collect data year-round will expand the knowledge of the country’s avifauna, and the presence of surveyors in protected areas would help deter illegal activities, as they witnessed during the logging run-in.

Boots on the ground are vital, says the BBPP’s Gonder. At Moraka, the sea turtle camp, poachers stay away when volunteers are present. When they leave, hunters move in, evidenced by the shotgun shells.

“We’ve seen a lot of international researchers and organizations come and go,” says Gonder. “Equatorial Guinea is a very challenging place to do conservation work. You have to have buy-in at all levels, from local people to the highest echelons of government.” The BBPP has worked extensively with the government to put in place conservation policies, to create protected areas on Bioko, to help found an environmental studies department at the university, and to hire locals to do everything from conducting wildlife surveys to providing tourism support. Gonder’s encouraged by the Biodiversity Initiative’s drive to return every year, to collaborate, and to expand its reach. “Luke and his people seem very committed,” she says, “and we need that here.”

Powell says they’re in it for the long haul—but not forever. “We want to become obsolete,” he says. “To train people here to do conservation science, and then let them protect their own natural heritage.”

Expedition members walk to Moraka field camp on the first day of the trip to the caldera, spotting numerous birds, including Western Reef-Herons and Pied Crows. Photo: Tristan Spinski

On our penultimate day in the caldera, we leave North Camp for Hormigas. Brzeski and Wolfe stop at the camera traps along the trail to swap out used cards for blank ones; a Moraka volunteer will retrieve them in April. They fall behind. Cooper is explaining his distrust of baboons and fear of snapping turtles when their screams jolt us to a stop. “Are they hurt?” asks Cooper. We can’t tell. We race back up the trail.

Brzeski and Wolfe meet us part way, she triumphantly holding her digital camera in the air like a trophy, he shouting: “Picathartes! Picathartes!”

Brzeski and Wolfe meet us part way, she triumphantly holding her digital camera in the air like a trophy, he shouting: “Picathartes! Picathartes!”

The scientists exuberantly exchange high-fives, everyone yammering as the red-capped bird hops comically across the screen. Powell asks, “What was the time stamp?” Brzeski checks. The bird triggered the camera 26 hours ago. “We’re going to try and catch it, right?” says Powell.

We have three hours of sunlight. Wolfe, visibly torn, goes with Brzeski to hit the other camera traps. The rest of us—Powell, Cooper, Motove, photographer Tristan Spinski, and I—will try to capture the elusive bird.

Powell is in full leader mode, instructing Motove to set up two nets, one on either side of the 150-foot-high ceiba tree the picathartes strutted past. He puts the chances of catching it at 10 percent. “Well,” he reconsiders after a moment, “make that seven percent.”

Cooper shares that skepticism. He’s spent countless hours in Cameroonian forests searching for this bird. Once, at a newly built nest, he waited so long he literally watched the mud dry. “We don’t stand a chance, but we have to try,” he says.

Nets up, we huddle around Powell for final instructions: We’re each to take a quadrant, face away from the net, and keep still. Spinski will position himself across from the tree, the best vantage point for getting a shot. If a pica wanders into our quadrant, we’re to let everyone know, then shoo it into the net. “It probably won’t hurt you,” Powell says. “It’s about one-third the size of a chicken.”

I am certain that if the bird enters my quadrant, I will blow the capture. I want reinforcements. I ask how to alert everyone if I spot the bird.

“Whistle the Carolina Chickadee song,” says Cooper. “Nothing here sounds like it.”

This suggestion is met with three blank stares. The photographer, the Equatoguinean, and I have no idea what a Carolina Chickadee sounds like.

Powell sighs. “Just shout, ‘Bird!’ ”

We wade into the brush and take position. Cooper starts the picathartes playback on his phone. It sounds like an inexperienced driver shifting gears. It could be an alarm call, a territorial call, a mating call—it’s the only one he could find, and nobody knows what message it’s sending the bird, assuming it’s even in earshot. The size of picathartes’ range is yet another unknown.

The wait is, at turns, exciting, nerve-racking, and tedious. At one point a crash nearby startles me and I slip off my log. Probably just a rodent.

After 45 minutes, Powell calls it quits. “Man, it’s out here somewhere,” he says. “We gotta come back.” Cooper pats him on the shoulder. They aren’t returning this year. Tomorrow we leave the caldera.

Porters appear the next morning and take off with our packs. After a last round of banding—nine birds, one a recapture—we follow, crossing the river, climbing up and out of the crater. We spend the night at Moraka, the crashing waves barely dampening the hyrax cries. The next day we retrace the path along the beach, each step drawing us closer to cold beer and fried chicken. The caldera rises in the distance, impossibly far away.

The scientists spread out at the Moka field station the next morning. Cooper is birding; he adds the Great Reed Warbler to the country list. Powell is organizing the info Fero will need to issue export permits for blood and feathers from the 780 birds the team captured throughout the monthlong expedition. Wolfe is doing laundry. Brzeski is on her computer, watching camera trap footage. She lets out a joyful WHOOP!

A week ago, four hours after we left Hormigas for North Camp, the waterfall camera recorded video of a picathartes jumping off a log on the ledge and crossing the shelf. Wolfe is vindicated. “I am convinced I heard it,” he says after seeing the footage.

In May Brzeski receives the six camera traps left out for nearly three months. They recorded 13,000 images. A menagerie parades across her screen: monkeys, bushbabies, cat-like oyans, pangolins, porcupines, duikers. And on every camera, picathartes. Multiple birds were there, hidden, perhaps watching furtively as we tromped through the forest, fruitlessly searching for them. For all we saw in the caldera, it seems we barely glimpsed the place.