Mud envelopes my feet, dark and cool, slick with sea. It’s low tide, and the sea has receded to reveal a massive mudflat stretching as far as the eye can see. We are at Tân Thành beach, roughly two hours by car from Saigon, on the coast of Vietnam’s Mekong Delta. It is early January—the dry season in the tropical south—when huge numbers of migratory shorebirds can be found on this expanse.

Following the lead of our guide, Ba and I cautiously navigate the ankle-deep water of a tidal channel. From atop the sea wall a storm-grey heron watches our slow progress. To the north and east, fishing huts perch high on bamboo posts. To the south, giant steel transmission towers dominate the horizon as they march offshore towards rows of wind turbines. On the muddy backshore, fishing boats lie stranded with nowhere to go, outsized eyes painted on their fading prows. They are the same kind of boats that my family used when we fled the country over forty years ago.

We are sloshing across the mudflats this morning because somewhere out there might be a spoon-billed sandpiper, one of the world’s rarest shorebirds and a critically endangered species. A few regular, if elusive, birds are recorded every winter here at Tân Thành. Our guide is Bùi Thành Trung—or, as he prefers it, Toby. He’s one the best birders in Vietnam, a shorebird specialist with a knack for finding “spoonies”, as he affectionately calls them.

“Stay inside the channel!” Toby shouts, spotting scope balanced over a shoulder. We have about two hours before the tide makes it too dangerous to be wandering the mudflats. We aren’t the only ones making the most of low tide. Further out, dozens of local women are digging for clams.

The watery path leads to the first set of makeshift bamboo “monkey bridges” we’ll need to cross. My seventy-four-year-old father stops in his tracks, considers the 30-metre obstacle course, his old knees, his bad balance, and tells us “kids” to go ahead without him. But Toby has just the pep talk. “You’re still cứng” he says, clenching his fist and smiling—still hard, still tough. That’s all it takes; Ba comes along.

There is something simultaneously exhilarating and comforting about being at Tân Thành. There’s no point bothering with footwear because they’ll only get stuck in the mud. Earlier, the act of taking off our shoes before setting foot on the mudflat called to mind the familiar Asian custom before entering a home. We are, after all, guests here in what Toby calls “Spoonyland”.

For the past few days, Ba and I have been on a meandering road trip through the Mekong Delta, from Saigon to the river town of Châu Đốc near Cambodia. He wanted to show me some of the places where he was stationed and fought during the war, some fifty years ago, as an officer of a patrol boat unit in the South Vietnamese Navy.

Today, we return to our primary mission: to experience Vietnam through its birds. Whenever we returned to Vietnam in the past, we usually spent all our time visiting family. For once, I wanted to see the country itself. On this matter, Ba and I found common ground. While he’s no avid birdwatcher like me, Ba likes a good challenge and wants to see as much of Vietnam as he still can.

Given the country’s long, distinctive coastline, a trip focused on shorebirds seemed essential, and searching for the spoon-billed sandpiper offered us a chance to do something extraordinary: witness a bird brought back from the brink of extinction. The guide I initially contacted was unavailable, but put me in touch with his friend, Toby. I knew about Toby from eBird, an online platform that birdwatchers the world over use to record and share sightings. Toby was the top “lister” in Vietnam, with 750 species observed—a distinction that filled me with unexpected pride when I first saw his Vietnamese name on top of a leaderboard stacked with Anglo-sounding names.

Toby studied business administration and held a decent desk job for an industrial sales company. Then, one day, a brief encounter with a sunbird ignited his passion for birds. More than ten years later, Toby has explored nearly every province in Vietnam on a quest to photograph every bird species in the country.

Reaching the sandbar peninsula, we catch our first glimpse of the shorebirds. I can’t make most of them out; they are only shapes flying back and forth. The birds are everywhere, in disorienting abundance, in wondrous array. How the hell are we going to find a tiny “spoonie”—a bird the …