Peter Kaestner illustration with birds flying around him
Lauren Mortimer
Peter Kaestner illustration with birds flying around him
(Illustration: Lauren Mortimer)

What It Takes to See 10,000 Bird Species

Peter Kaestner has traveled the world on an adventure-filled quest to become the first birder to hit 10,000. Ornithologist Jessie Williamson hitched a ride on a rollicking South American mission that involved land, sea, and (you guessed it) air.

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Editor’s Note: Since this story ran in print (in the May/June 2023 issue of Outside), Kaestner’s life list has increased to 9,856 species, as of May 11, 2023. He is now the world record holder.

The dry valleys outside Lima, Peru, evoke the feeling of being on another planet.

Dust as fine as talcum powder washes the landscape in desolate browns, and bromeliads cling to the west side of rocky slopes, facing the direction that mist blows in from the ocean. Columnar cacti the size of telephone poles resemble hands outstretched toward the sky—puffy, like surgical gloves filled with water.

I was sitting in the middle seat of a battered van snaking up switchbacks to the summit of Tinajas Valley, tires inches from the edge of steep drop-offs. Next to me was Peter Kaestner, one of the world’s most prolific birders. “I can see why I haven’t seen this bird before,” he said, speaking loudly as the van rumbled over dirt and rocks. “It’s not the kind of thing you’re gonna bump into.” Kaestner is tall, with friendly blue eyes, and gives off a smart approachability. (He jokes that when he was younger he resembled Robert Redford, but he knew that he’d hit a turning point in his life when people started comparing him to former Syrian president Hafez al-Assad.)

We were headed to a ridgetop to look for the elusive white-throated earthcreeper, a drab brown bird with a curved beak like a T. rex claw. The bird prefers steep-walled desert washes at specific elevations in the central Andes, and would be a “lifer” for Kaestner. Birders call the complete tally of all birds they’ve ever observed their “life list,” and each new species a lifer. A person who keeps track of their life list is a “lister,” and someone obsessed with listing on a global scale is a “big lister.”

I’m a lister myself, though I spend more time researching birds than chasing them. For my PhD at the University of New Mexico, I studied hummingbird migration and speciation in the Andes. These days I work as a postdoc at the Cornell Lab of Ornithology, which runs eBird, the go-to platform for scientists and hobbyists to record bird observations.

On eBird, Kaestner is ranked number one, and he wants to be the first person in the world to see 10,000 bird species. The 69-year-old’s life list is currently at 9,796. The couple hundred birds he still needs are some of the rarest and most difficult in the world to spot. They’re often found in places that are basically inaccessible, off-limits due to political unrest, or threatened by deforestation and climate change. But Kaestner’s quest to hit 10,000 is his personal Dawn Wall, an obsession he’s sustained over decades, and he will not stop until he reaches his goal—if even then.

He’d come to Peru on this 20-day trip in the summer of 2021 to see a handful of the country’s remaining species needed for his life list, and the journey had started out a little rough. During his first night above 15,000 feet, near the Bolivian border just ten days earlier, Kaestner thought he might die of altitude sickness. On an overnight bus to the city of Oxapampa soon after, the driver turned off the air-conditioning over a mountain pass and the cabin became hot and stagnant. COVID risk was high, and Kaestner said the bus felt like a human petri dish. His trip wouldn’t get easier: for one of his top targets, the Ayacucho antpitta, he needed permission to navigate through an unstable area ravaged by Shining Path guerrillas. He expected the middle leg, which I had joined him for, to be relatively tame. “Boring” was the word he used.

As our van slid past another huge vehicle on the singletrack road, tires knocking rocks down the cliffside, I held my breath and wondered about his standard for boredom. Then, as a truck came nose-to-nose with our van, the clutch stopped working. We were on a steep hill.

“There’s too much dust—it must be clogging the transmission,” said Gunnar Engblom, guide and owner of Kolibri Expeditions, who had organized our trip. A lanky Swedish rocker and marathoner who was 60 at the time, Engblom had come to Peru about 25 years earlier to start his bird- and photography-tourism business. He switched from English to frantic Spanish, addressing our driver from the passenger seat.

A look of annoyance appeared on Kaestner’s face. We’d departed late from Lima, then battled incessant traffic, and it was unclear whether Engblom’s run-down van would even make the summit. At best this meant that we would arrive in the hot afternoon, the worst time of day for bird activity, before driving another eight hours to our next destination. Engblom’s reputation as “Captain Chaos” was well-known in the bird world (one client described him as the “Crocodile Dundee of South America”) and Kaestner knew what he was getting into. Still, even for Kaestner, a former U.S. diplomat who built a career managing high-stakes logistics, the situation was trying. After all he’d invested, he didn’t want to miss his target—or “dip,” as birders say.

Green-Capped Tanager
Green-Capped Tanager: Spotted by Kaestner in June 2021 in Puno Department, Peru (Lauren Mortimer)

Kaestner has taken a nontraditional path to reaching 10,000. The pursuit is often considered a rich person’s pastime, like climbing the Seven Summits: many obsessive listers and bird chasers take months or years off work, spend personal fortunes, retire to chase birds full-time, or turn to vanlife. Kaestner is an exception. He birded his way to about 9,500 while working for the Foreign Service for 36 years on a modest government salary. He and his wife, Kimberly, a diplomatic specialist, fought for tandem placements so they could work together overseas, and he often achieved his birding goals through creative scheduling. While living in Kuala Lumpur, Kaestner left the house at 3 A.M. on Saturdays to drive more than two hours each way in search of the rusty-naped pitta, returning to the Malaysian city by noon to play with his young daughters. “It took me over two dozen trips to get that bird,” he says. “But I wanted to be home to spend the afternoon with my family.”

“He does go off on his birding trips where it’s just birding, but he always makes time for family,” says Kimberly. “He’s always been good that way.”

Rotating through embassies as a diplomat allowed Kaestner to get ahead as a big lister. He’s lived all over the world: the U.S., Central and South America, Africa, the Middle East, Southeast Asia, and the South Pacific. During his career, he’s studied 13 languages. He once spoke six—English, Portuguese, Spanish, French, Hindi, and German—with professional fluency, plus a handful of “birding languages,” as he puts it, with proficiency adequate for getting by on birding trips: Swahili, Bahasa, Arabic, Punjabi, Dari, neo-Melanesian, and Afrikaans.

Kaestner’s quest to hit 10,000 is his personal Dawn Wall, an obsession he’s sustained over decades, and he will not stop until he reaches his goal—if even then.

In 1986, Kaestner became the first person in the world to see a representative of every bird family in existence, 159 back then. But the birding event that most changed his life was his 1989 discovery of the Cundinamarca antpitta, a species new to science. Kaestner had traveled outside Bogotá, Colombia, for work and was exploring a forested area up a newly constructed road. Suddenly, he heard a call he didn’t recognize.

He recorded it, then played the call repeatedly to lure the bird in, waiting for over 45 minutes. At one point, the bird popped up and called behind him. He crawled through the undergrowth and reached a clearing. Then Kaestner saw it. It wasn’t a known Colombian bird, he was sure of it. But back then, the references he needed to verify whether it was a new bird for Colombia, or a new species entirely, didn’t exist. Upon returning to Bogotá, he confirmed that it was a species previously unknown to science; it was formally described by biologists in 1992. His recordings and dictated field observations are now archived in the Cornell Lab of Ornithology’s Macaulay Library. For Kaestner, who has always been driven to contribute to the scientific record, the discovery was monumental. Antpittas remain his favorite birds.

The days of stumbling upon a new species in the forest are essentially gone; it’s now far more common for scientists to use genetic and molecular tools to identify species no one previously knew existed or could confirm. Species identification has become knottier as a result, and systematists, who study relationships among species, may use DNA evidence to split known species into multiple ones. In 2020, for example, biologists argued that the rufous antpitta—a bird that looks like a caramel-colored truffle with popsicle-stick legs—was not one but sixteen distinct species, though they look almost indistinguishable.

These splits have enormous implications for someone like Kaestner, who needs every single species he can get to reach 10,000. Kaestner had seen the rufous antpitta, for example, many times in different parts of the Andes. Previously, it counted as just one species for his life list. But with the split distinguishing 16 separate species, many of Kaestner’s past sightings—thanks to his careful record-keeping—would bump up his total. (Platforms like eBird calculate these tallies automatically.) For Kaestner, these free “armchair ticks” are like a bag of Halloween candy falling into his lap.

The recognition of new species—sometimes dozens each year—also raises the question of how many bird species there are in the world. The number is a subject of heated debate among biologists. There are four master checklists of the world’s birds, each with its own set of taxonomic rules. The lists agree on roughly 85 percent of species; the rest are considered “good” species by some lists but not others. Depending on the list, the world’s bird species can number between 10,906 and 11,189. Kaestner and many other competitive listers prefer the International Ornithological Community’s World Bird List, because it’s more generous than the Clements Checklist used by eBird.

Some listers try to anticipate species coming down the pipeline, designing trips to see “bank birds” that they hope will one day be ruled new species. Kaestner was partly pursuing this strategy in Peru. The taxonomic splits of the rufous antpitta thrilled him. He had come to chase these splits and to see five new species before they were recognized by taxonomic authorities. He’d bagged four so far, including two in one day (Oxapampa antpitta and Junin antpitta), and would target another after I left.

White-Throated Earthcreeper
White-Throated Earthcreeper: Seen in July 2021 in the dry valleys outside Lima, Peru (Lauren Mortimer)

In the dry Tinajas Valley, the semi inched closer to our van, pushing us downhill as we struggled with the faulty clutch. When the truck finally slid past, our driver found that he could shift again, and we lurched forward.

We reached the top of the valley under a blazing noon sun and jumped into action, grabbing cameras, binoculars, and speakers. We hadn’t eaten lunch, but hunger could wait. We walked along the road, scanning dirt embankments where earthcreepers are known to roost, while Engblom played the bird’s vocalizations. A yellow-billed tit-tyrant called. Groups of long-tailed mockingbirds hunkered down inside tangled cacti, waiting out the heat.

An hour passed with no luck, and we split off in different directions. Spiny shrubs and cacti dotted the steep slopes, and their thorns and stickers collected in my socks.

Eventually, Kaestner circled back to me. It was dead silent until a robin-size brown bird scurried across the ground in front of us, disappearing in a flash. Our hearts leaped—but it wasn’t the earthcreeper.

“C’mon, baby,” Kaestner said to himself, scanning the brushy slopes.

It was 1 P.M. and we had a long drive ahead of us. Engblom suggested alternate plans, but Kaestner wasn’t ready to give up. A short path nearby led to a sloped wash where the habitat looked good, and Kaestner wanted to follow it. We walked down the path and played the earthcreeper’s call. Miraculously, within minutes, a bird responded.

“That’s it, that’s the bird below us!” Engblom yelled.

“Uh huuuhhh!” said Kaestner, grinning and giving me a thumbs-up.

The bird slunk around in the low brush before hopping to perch on a rock right in front of us. We snapped photos to document the sighting for eBird. Back in the car, Kaestner slapped his knees excitedly. “OK, Gunnar, great bird!” Our success had temporarily erased the stress of the morning’s trek.

But we couldn’t waste time celebrating, and immediately got back on the road. By 3 P.M. we’d dropped below Lima’s fog layer to the gray city outskirts, where it was at least ten degrees cooler than the summit we’d just left. We were now six and a half hours from the city of Nazca, our next destination, where, in between antpitta sighting attempts, Kaestner wanted to tick off a few other target birds in the frigid Pacific.

We drove toward the small fishing town of Puerto de Lomas, whose main allure for birders is its proximity to deep-sea canyons, where Humboldt Current upwellings attract some of the world’s most prized seabirds. En route we slept for a few hours in the town of Palpa before waking at 3:30 A.M. to finish our drive. We cruised past the Nazca Lines, a Unesco World Heritage site known for its geoglyphs. No one in the car noticed. Kaestner blasted music from his portable speaker to help our driver stay awake: Adele, Abba, then Celine Dion’s “My Heart Will Go On.” He didn’t seem to register that he was playing the Titanic theme as we catapulted toward the open ocean, where we’d spend the day in a rickety fishing boat. I asked Engblom if there would be a bathroom on board. “A bucket, and everyone looks the other way,” he replied. “It’s best to take care of that beforehand.”

We arrived in Puerto de Lomas under an overcast dawn sky. The small marina, no more than an inlet, was filled with dozens of petite, colorful fishing boats secured to one another like a giant life raft. Belcher’s gulls squealed and begged for food, jostling for space among the people.

To reach our boat, we had to walk across three others. The first two were steady in the water, but the last was much smaller and rocked like a seesaw in the current. I grabbed a fisherman’s outstretched hand, slimy from the catch he’d just gutted, to keep my balance as I stepped onto our vessel.

A split second later, Kaestner joined me on deck. The boat was bright blue, about 20 feet long and 5 feet across, with a 40-horsepower Yamaha outboard motor. It had no sun cover, no bathroom, no railing, and no backup motor. We found three life vests tied together neatly—a good sign they weren’t often used.

Soon our boat driver, Zorro, began navigating out of the marina. Within a few minutes we hit our maximum cruising speed of five miles per hour.

Our goal was to reach the edge of the continental shelf and its adjacent deep-sea canyon, located roughly ten nautical miles offshore. There we would have the best chance of seeing Kaestner’s two targets: the ringed storm petrel and the Markham’s storm petrel. Storm petrels, called “sea swallows” in Spanish, are robin-size birds that skim the water with a fluttery, bat-like flight in search of crustaceans, small fish, and oil droplets. They spend nearly all their time at sea, only returning to land to nest in stinky underground holes in the Atacama Desert. They have tiny legs that dangle above the water, making them look as if they are pitter-pattering across the ocean’s surface. Sailors long believed that storm petrels were bad-luck “witches” that could predict storms; some thought that the number of storm petrels in a flock was a sign of how severe a storm would be. Biologists still know very little about them, and the two species we were after are typically only seen miles away from the South American coastline.

The wind picked up the farther we got from shore. The boat roiled in six-foot swells, and Kaestner and I clung to two wooden poles near the hull. We were a foot from the edge, and each violent lurch brought the ocean closer. Both of us had taken Dramamine that morning, but seasickness seemed unavoidable. It was best to avoid talking about it, so I focused, as if hypnotized, on the horizon.

“I take back everything I said about boring,” Kaestner announced, keeping his eyes forward and scanning for fast-flying seabirds. “This is easily the most unseaworthy vessel there ever was.”

I smiled thinly and looked around. Engblom sat behind us on an outstretched cushion, neon toe shoes dangling over the edge as he casually ate cereal. Our driver sat on the back wall of the boat, tiller-steering, completely at home.

A little while later, we encountered a pod of dusky dolphins. Kaestner remarked that dolphins normally swim with a boat, riding in its wake or along the sides, but we moved so slowly that they completely circled us before we advanced. As we moved into deeper, colder water, the bird community began to change: sooty shearwaters, named because they skim so close to the surface that they sometimes cut the water, bombed across the horizon, and a tiny Elliot’s storm petrel appeared and disappeared like an ocean ghost. Suddenly, when we were about nine miles offshore, a massive shape appeared on the horizon.

“Black-browed albatross!” yelled Engblom. Its nearly seven-foot wingspan sliced the sky like a knife. An albatross this close to shore was a good sign: it meant we’d reached a productive spot. The swells were modest and the wind was favorable, so we decided to chum.

Zorro killed the engine and placed a big yellow bucket on deck, filled to the brim with entrails and shark livers. With his machete, he cut off pieces to throw into the sea. Across from him, Engblom squirted fish oil onto the water’s surface, then emptied a box of cornflakes into the ocean. Seabirds have an excellent sense of smell, and we hoped the chum would attract visitors: the corn flakes for Kaestner’s target storm petrels, the meat for bigger birds like albatrosses.

Chestnut-Eared Aracari
Chestnut-Eared Aracari: Observed in July 2021 in the lowlands of Cuzco, Peru (Lauren Mortimer)

Kaestner doesn’t remember a time in his life when he wasn’t birding. His eBird profile features a photo of him at age three or four with a pair of binoculars around his neck. Though many birders have a “spark bird” that first piqued their interest, Kaestner’s introduction was different. His elder brother, Hank, had a memorable encounter with a vermilion flycatcher in Mexico City in 1955 and got hooked. Kaestner looked up to his brother and piggybacked off him; if Hank was into birds, he was, too.

Kaestner grew up in Baltimore with nine siblings. “Everything in the family was always very competitive, including birding, eating, identifying cars,” he says. “The competitive side is something that’s ingrained in my personality.” In the Kaestner household, the first person to finish eating got extra dessert. Every so often, their dad threw a pocketful of change on the floor of the TV room, and the siblings would fight over it—like Lord of the Flies.

“I was a birdwatcher, and we were so similar, it was like, ‘OK, bird-watching, that’s what we’ll do,’ ” Hank says.

Kaestner attended Cornell, intending to become a professional ornithologist. But over the course of his undergraduate studies, he changed his mind, deciding that he would enjoy life more—and see more birds—by having a non-ornithological occupation. After earning his degree in biology, he joined the Peace Corps in Zaire (now the Democratic Republic of the Congo) in 1976, and two years later he began his career as a diplomat.

“My relationship with birds is multifaceted,” Kaestner says. He loves them aesthetically and scientifically; he enjoys their beauty, behavior, and the sense of amazement they give him. Even the sight of the same European robin singing its heart out in the Frankfurt cemetery on Kaestner’s old walk to work would bring him joy. Though he mostly birds alone, he appreciates the social aspect of birding: explaining, teaching, and sharing his passion with others.

Birds also push him out of his mental and physical comfort zone. In April 2021, he hiked to a remote section of the Sierra Nevada de Santa Marta in Colombia in search of the blue-bearded helmetcrest hummingbird, a species lost to birders and scientists for nearly 70 years until its rediscovery in 2015. He dropped 50 pounds to prepare for the quest and hiked more than 12,000 vertical feet in three days.

Even the sight of the same European robin singing its heart out in the Frankfurt cemetery on Kaestner’s old walk to work would bring him joy.

“If I had not needed to see a blue-bearded helmetcrest, I would not have done that,” he said. “To get up there, when your legs are aching and your feet have got blisters on them and are screaming to stop and hop on the mule—that’s all about birds.” At the summit, masked and slightly out of breath, he recorded a selfie video that he later posted to Facebook, exclaiming: “Just got my first view of the helmetcrest! Now we just gotta get a picture.” His joy was palpable.

“It’s not all about competition,” he told me. “Competition is important, but the beauty of birds, the wonder of birds, the science of birds, traveling the world to see birds—all that is equally important.” Then, laughing, he added, “And the numbers. I love numbers.”

Kaestner has a fascination, perhaps an obsession, with numbers—particularly round ones. If he’s out birding and he’s seen 89 species, he will work hard to get to 90. If he’s changing the volume of the car radio and it stops at 13, he moves the dial up to 15 or down to 12 to avoid stopping on a prime number. “Ten thousand is a great number,” he says. “It’s the ultimate milestone, a one with four zeros!”

Kaestner is a gifted storyteller. Hearing him recount birding adventures is as soothing as listening to an experienced baseball announcer. After a few days in the car together, I felt like I could recount his tales, too. During his second Foreign Service tour in Papua New Guinea, for example, he traveled to a remote outpost of an evangelical missionary group—a village of 30 or 40 houses that was a ten-day walk from the nearest road—in a tiny “whirligig” helicopter. To Kaestner’s delight, the village had arranged for a local guide and translator to take him into the forest. When the guide arrived, he was wearing what appeared to be the front part of a human skull around his neck—the translator explained it was probably from a vengeance killing. During the team’s walk through the forest, they spotted a dwarf cassowary, a large emu-like bird that is increasingly human-shy due to overhunting. To this day, it remains the only dwarf cassowary Kaestner has seen.

Even Kaestner’s wedding day in Orchard Lake, Michigan, is marked by a bird memory: Peter and Hank had planned to undertake an ambitious drive that morning to chase the rare Kirtland’s warbler, returning in time for the ceremony. Kimberly said, “Absolutely not.” Peter says it’s the only time she’s ever forbidden him to bird. About a year later, Kimberly chose to name their pet cat Kirtland, because for a long time the Kirtland’s warbler was one of the only birds she’d seen that he hadn’t.

Just 30 seconds after we chummed, storm petrels began arriving from downwind of the scent. Soon hordes encircled the boat, dancing across the water to scoop oil droplets off the surface. Bigger seabirds hawked chunks of meat out of the water, clawing at each other for liver bits.

We waited, watching the pitching sea. Dozens of storm petrels—all Elliot’s and Wilson’s—danced in the water around us. A waved albatross, which can live for 45 years, made several passes around us, then disappeared into the gray of the horizon. Suddenly, guanay cormorants erupted everywhere and streamed across the sky, carpeting the ocean as far as the eye could see. We watched them for nearly five minutes, estimating that they numbered over 100,000. The traffic and diversity of seabirds were exciting, but we all avoided thinking the obvious: Where were Kaestner’s targets?

Finally, Kaestner shouted, “Ringed storm petrel! Ringed storm petrel! Right here, three o’clock!”

Unlike the more common storm petrels around our boat, the ringed storm petrel was much larger, with a bright white belly, dashing sooty collar, and white chin. Its wings had silver crescents that made them pop against the waves. Kaestner was elated—one down, one to go.

Sensing that the bird activity had died down, we moved upwind of our chum. Engblom added more fish oil and corn flakes to the water. Zorro tossed shark liver overboard, then lowered a string of entrails on a rope into the water. They roiled in the churning waves as frenzied seabirds ripped at chunks, gawking, clawing, and squealing their way to the meat. We waited an hour and a half, carefully scanning for storm petrels. We saw four species of albatross and a few other unusual seabirds, but no Markham’s. The fatigue from the cold, wind, and seasickness set in; my eyelids drooped.

At 11 A.M. we pulled the plug. Kaestner stomached his silent disappointment with the stoicism of an Olympian realizing they won’t finish a race. I asked him if he would come back again to try for a Markham’s. “Maybe,” he said. He could get it in Chile, but he would only go if he could combine it with other targets. Repeating this trip would be too costly and too much effort for one bird alone.

Swallow-Tailed Hummingbird
Swallow-Tailed Hummingbird: Glimpsed in July 2021 at the Ipal Ecolodge, in Cuzco, Peru (Lauren Mortimer)

Joining the big-lister club requires tremendous sacrifice. Fewer than 60 people have ever seen more than 8,000 bird species, and fewer than 20 have gotten above 9,000. It demands exceptional, almost singular, devotion to the pursuit, often to the point of forsaking family, friends, hobbies, and a “normal” life.

Kaestner has followed in the footsteps of many of these birders, including the legendary Phoebe Snetsinger, the first person to see more than 8,000 species and a former world-record holder. Snetsinger died in a car crash in 1999 on the way to see her 8,399th lifer, in Madagascar. She’d become a competitive birder after being diagnosed with terminal melanoma, famously missing her daughter’s wedding for a birding trip to Colombia. Kaestner and Snetsinger met only once, but Kaestner impressed Snetsinger, who wrote in her autobiography that she admired his skill and philosophy of “work like hell and be helpful to people.”

Birders have been marooned, kidnapped, and raped while in pursuit of birds. One was eaten by a tiger in India but got pictures of it before his demise. Kaestner has gotten lost climbing Mount Kolombangara in the Solomon Islands and shipwrecked in the Amazon. He also claims to have an “electric butt”—he’s been tossed off horses more times than he can count.

At press time, there is only one known person in the world with more species—by just two—on their life list than Kaestner: Claes-Göran Cederlund, known as CG, who is dead but still racking up species from the grave as taxonomic authorities update world bird lists. Kaestner once received an email about a guy who’d supposedly gotten to 10,000—Kaestner reached out directly to verify, but the report turned out to be false. (Competitive birding has no official scoreboard, and it isn’t overseen by any governing body, so keeping track of the leaders and players can be challenging.)

Kaestner’s biggest competitor, Ross Gallardy, is currently far behind him. Gallardy’s life list totals 7,670 species, but he’s only 34 years old—and he’s ambitious and scrappy. Gallardy works as a logistics and operations consultant for PricewaterhouseCoopers, but when possible he takes the vanlife approach to competitive birding. In 2020, Gallardy and his wife, Melissa, bought a souped-up Toyota Hilux, planning to spend ten months blogging through Africa. Their goal was to “bird their asses off,” as Gallardy put it, to see as many species as possible and shatter the record for the highest number of species seen in Africa in a single year. (Their trip and record attempt were interrupted by COVID-19, but they returned in 2021 to finish.) The couple runs the website Budget Birders, where they promote world listing on the cheap. They don’t typically hire guides or go on organized tours, relying instead on their own know-how and “gen”—short for general info, like beta for birders—from others.

Gallardy aims to be the youngest person in the world to see 9,000 species. But, unlike Kaestner, he says he doesn’t care about numbers. “Honestly, I don’t,” he told me. “I just like birding, and I like seeing a lot of birds. At the end of the day, the numbers happen, but I’m not competitive at all when it comes to birding.” Later, he added, “I am not casual about missing birds—that is a whole other thing. My wife always jokes that I get ‘bangry.’ When I’m missing a bird, I get angry.”

In July 2021, Gallardy blogged that he may have discovered a new species of sunbird from a remote section of the Rubeho Mountains in Tanzania. If verified, Gallardy will be credited with finding a new species at about the same age that Kaestner was when he found the Cundinamarca antpitta. After Gallardy posted about the find on Facebook, Kaestner commented, “Outstanding!!!! Congrats.” Gallardy jokingly replied: “It’s no antpitta, but I guess it’ll do.”

Birders have been marooned, kidnapped, and raped while in pursuit of birds. One was eaten by a tiger in India but got pictures of it before his demise.

During Gallardy’s overland Africa trip, Kaestner texted Gallardy with advice about where to find the critically endangered Taita apalis in Kenya, in a patch of habitat with dense vine thickets. Kaestner’s gen worked: Gallardy got the bird. I started to ask Kaestner if he feels conflicted about giving Gallardy advice, but he interrupted before I could finish: “No, it’s not that kind of competition. I would help him with any bird he needs, and he would help me with any bird I need.”

Still, Kaestner thinks he has a relatively narrow window to beat his contemporaries and stay ahead of Gallardy. “Ross is very good, he does his homework, and he spends a lot of time trying for night birds. And he doesn’t spend any money, he’s doing it all on a budget,” Kaestner says. “People like Ross are taking advantage of tools I never had 34 years ago. I’m not yet number one, and I know Ross is my successor.”

When Kaestner started birding seriously, he didn’t have eBird or other online resources. In those days, field guides with photos and written descriptions of birds didn’t exist for many countries. Birders maintained their life lists differently. Phoebe Snetsinger used meticulously organized, color-coded index cards, writing, rewriting, and reshuffling them by hand when taxonomies changed. Kaestner used to read biologists’ academic papers to find spots where they’d studied certain species. When Kaestner discovered the Cundinamarca antpitta, he couldn’t compare the bird’s vocalizations with others uploaded online. Now sites like eBird and iGoTerra automatically update birders’ life lists for them.

Kaestner believes that it’s much easier to get to 10,000 today than ever before. Though some species have become rarer due to habitat loss and climate change, the tech resources, road access, and tools that now exist have made finding birds significantly less challenging. But the game remains far from easy. “The only question is whether I have the drive and funds to continue doing it,” Kaestner says.

Stopping short of 10,000 seems unlikely. Kaestner doesn’t waste time, and age hasn’t slowed him down. In our six days together searching for 12 rare birds, we took two flights and drove over 1,500 miles on winding mountain roads. We spent more than 50 hours in the car, sometimes nearly 11 hours per day. More than half our meals were skipped or eaten in the car. We slept less than four hours on three of the six nights, arriving at our destinations in the dark and leaving well before sunrise.

“Sleep is for the faint of heart,” he told me half-jokingly in the car one day. “It’s sort of like SEAL training—stay up for 48 hours and see how you solve problems.”

Toward the end of our trip, we traveled across greater Cuzco, traversing from high peaks to humid lowlands. It was late afternoon as we snaked along the Urubamba River en route to the jungle town of Kiteni, and everyone was feeling sleepy.

“Holy shit,” Kaestner said abruptly.

“What?” we all replied.

He looked up from his phone. “The IOC update is due out soon,” he said. “The last time I checked, they were proposing 46 splits. Now they’re proposing 107.”

Because Kaestner has seen so many birds, he typically gets about half of the new species recognized each time the taxonomy is updated. That year’s 107 splits could mean upward of 50 new species for his life list.

A few weeks later I confirmed: the trip to Peru put Kaestner in a good position. He’d bagged 15 lifers, and after the IOC update in mid-July 2021, his list shot up by 55 additional species.

Since our trip to Peru, Kaestner has birded in Germany, Italy, the UK, Poland, the Czech Republic, Panama, Ecuador (twice), Colombia, Suriname, Brazil, Ethiopia, India, the Seychelles, Azerbaijan, and Svalbard. In the fall of 2022, he visited northwest Argentina and then spent a few weeks guiding a birding tour to southern Argentina and Antarctica. As of press time, Kaestner was on a ten-week birding trip in Southeast Asia. Though he doesn’t have his path to 10,000 charted blow by blow, he told me that he has a plan for his next few hundred species through 2025, and he knows where he needs to go and when.

It’s unlikely that reaching 10,000 will mark the end of Kaestner’s birding. One morning as we passed through the village of Ollantaytambo, I caught him marveling at a gnarled tree growing through a cobblestone street. “The thing I most admire about trees is sustained effort over a long, long time,” he said. It was 4 A.M., and he didn’t seem tired.

From May/June 2023 Lead Illustration: Lauren Mortimer