Every morning, the smooth-coated otters of Singapore patrol their urban territories to guard against invading clans. Traffic wardens hold back cars and motorbikes as the intelligent animals wait, then scamper across busy roads. But, in scenes from the BBC’s new six-part documentary series, “Mammals,” city life is clearly a challenge for the resident otters. An infant is seen being separated by cars from his family, left alone to fend for himself, his life at risk from rival otter groups.

By selecting mammals as their theme, the filmmakers of the BBC’s Natural History Unit (NHU) have rich pickings, from the largest animal on Earth, the blue whale, to the tiny Etruscan shrew. Sixty-six million years ago, an asteroid collided with Earth, causing a mass extinction that wiped our three-quarters of animal life. “Out of the darkness that followed emerged a group that went on to dominate the world,” David Attenborough says, speaking directly to the camera, at the start of the series. “That group is the mammals.”

For 70 years, Attenborough has been bringing the natural world into the living rooms of billions of people around the world, collaborating on more than 100 series with the BBC’s NHU, including “Planet Earth,” “The Blue Planet,” “Frozen Planet,” “Africa” and “Dynasties.” With his skills as a writer and producer; his distinctive, often-mimicked voice; and his combination of passion and deep knowledge, he has inspired generations of conservationists, scientists, photographers, filmmakers and wildlife lovers to care about, and for, the natural world, with famous fans ranging David Beckham to Billie Eilish. Like the English primatologist Jane Goodall, he’s globally admired for raising awareness about biodiversity loss, climate change and other threats. Fellow British TV presenter Chris Packham has described him as “the world’s greatest broadcaster and the man who has done more than anyone has or ever will to protect life on Earth.”

But “the voice of nature” has grown more somber and desperate through the decades as Attenborough has seen firsthand the destruction humans are wreaking on the planet. The tone of his programs has shifted from joyful wonder to warnings of what we stand to lose if we don’t change course. Our reckless disregard for nature isn’t new—one segment in “Mammals” focuses on the wiping out of bison in North America in the 19th century—but the destruction has accelerated and spread dramatically over the course of Attenborough’s long and productive life.

Like many of the NHU’s previous productions, “Mammals” is primarily about the magic to be found in the natural world, such as the rarely seen nocturnal life of a shy fennec fox in the Sahara. One particularly astonishing scene in the “Water” episode features the crew’s small submarine, a mile beneath the ocean surface, being visited by a giant creature—I won’t spoil the surprise by saying which one.

But the recurring theme of “Mammals” is the adaptability and ingenuity of animals, particularly in response to new challenges in a world being dramatically altered by humans, from expanding cities to rampant agriculture. Film crews show sea lions emerging from overfished oceans and taking to the shore in Chile, where they scrounge fish from local markets. Elsewhere, we see howler monkeys traveling along electric wires in Costa Rican towns and wolves finding sanctuary from hunters among unexploded landmines in the Golan Heights. The show strikes joyous notes—Singapore’s otter family is eventually reunited, after the infant’s anguished night alone—but one of the most powerful elements in “Mammals” is the poignancy of seeing wild animals struggling to survive in urban environments.

As Attenborough, who has perhaps seen more of the natural world than any other living person, knows, though, not all animals are able to adapt to a rapidly and drastically changing world, such as the whales filmed here tangled in “ghost nets,” or abandoned fishing gear, which will kill them slowly and painfully. Even though Attenborough’s voice has reached hundreds of millions of viewers, the planet’s wild places and inhabitants are far worse off today than they were when he started making documentaries. “There are more than 6,000 species of mammals on Earth, but their fate lies in the hands of just one: us,” he says in “Mammals.” “If we make the right decisions, we can safeguard the future not just for our fellow mammals but for all life on Earth.”

A brief history of Attenborough

It’s a far darker view of the world than Attenborough would ever have imagined as a young boy. Born on May 8, 1926, in Isleworth, West London, he was hooked on the natural world from an early age. “I’ve always found fossils very interesting,” he told me, when I interviewed him over a decade ago. “I had newts and grass-snakes and frogs, which I kept in various aquaria when I was a boy. I spent a lot of time in the garden, exploring.”

After studying zoology and geology at the University of Cambridge, he spent two years in the Royal Navy, before starting his career in television in the 1950s with the emerging British Broadcasting Corporation. (At the time, like most British people, he didn’t yet own a TV himself.) He got his break in front of camera as the host of “Zoo Quest,” first broadcast in 1954, when the regular presenter became ill at short notice. Early on, though, his TV career was threatened when one BBC controller deemed his teeth too big for TV.

Zoo Quest For A Dragon (1956) With Sir David Attenborough | BBC Earth

Attenborough moved quickly into senior management, serving as controller of BBC Two and director of programming for BBC Television in the 1960s and 1970s, alongside presenting occasional programs about his global adventures. The BBC’s NHU was formed in 1957, but only with 1973’s “Eastwards With Attenborough,” from a trip to Indonesia, did Attenborough’s fruitful collaboration with the unit begin. Attenborough went on to write and produce the groundbreaking “Life on Earth” series, which first aired in 1979. With an estimated audience of 500 million people, the series made Attenborough a household name—and featured the now-famous scenes of the jubilant presenter lying in the undergrowth with Rwanda’s mountain gorillas.

David Attenborough Plays with Cute Baby Gorillas | BBC Earth

How innovations changed Attenborough’s specials

Besides the most obvious shift from the early days, when Attenborough’s TV adventures were filmed and aired in black and white, wildlife filmmaking has changed in numerous other ways, especially the NHU’s technical innovations throughout the decades, including fitting cameras onto the back of eagles and elephants to give viewers the animals’ perspectives; using high-speed cameras to slow down rapid movement, like the flap of a hummingbird’s wing; plus time-lapse cameras, drones, and infrared and thermal imaging. These new techniques have allowed the NHU to capture remarkable behaviors on film for the first time in history, such as dolphins stirring up mud to trap fish, or killer whales beaching themselves to hunt sea lions.

In “Mammals,” the NHU continues to push nature television forward, from mesmerizing monochrome footage of a hyena bringing down a buffalo at night in Tanzania’s Ngorongoro Crater—filmed using specialized heat-sensitive cameras—to captivating drone work that shows animals in their vast, wild environments, such as a polar bear wandering across the Arctic. At one point, a cameraman uses an underwater scooter to propel himself through the ocean to capture whales and bottlenose dolphins as they create bait balls and hunt fish.

Epic Leopard Hunt in Night Vision | 4KUHD | Mammals | BBC Earth

Attenborough, who turns 98 this year, appears briefly at the start of “Mammals,” but for the rest of the series his presence is confined to the role of narrator; bowing to the restrictions of age, he travels less each year. He’s had double knee surgery and heart surgery to fit a pacemaker. One of the most well-traveled people on the planet, he’s said to have journeyed 256,000 miles just for his 1998 “The Life of Birds” series. That’s the equivalent of going around the world ten times, which would be impossible to justify today, even if he were physically up to the task. (Most wildlife and natural history filmmakers have pointedly reduced their air travel in recent decades to minimize the irony of their contributing to climate change while creating programs that strive to highlight the problem.)

Over the past six decades, Attenborough has attained icon status for his intrepid, TV-savvy adventures, bringing viewers along with him into rainforests, deserts and icy wildernesses, even presenting from underwater using adapted scuba gear for 1984’s “The Living Planet” and diving 1,000 feet to observe the Great Barrier Reef in a Triton submersible. When we spoke, he described himself as “the last in a particular style. People make different kinds of programs now. I don’t think anyone’s trying to fill my shoes.” Although he was being humble, and premature, it’s true that many wildlife films have done away with in-situ presenters in favor of voiceovers from Hollywood actors, losing the kinds of scenes Attenborough has specialized in, from reporting alongside Lonesome George, the last Pinta Island tortoise in the Galápagos, to saying “boo” to a curious sloth.

Many of the scenes Attenborough has filmed on location, especially his rolling around with gorillas, wouldn’t be allowed today anyway, given safety concerns for the animals as much as insurance concerns for the presenter—and to avoid inspiring copycat behavior from viewers. But not having to transport an indomitable presenter between global locations also removes huge costs, dangers and logistical difficulties for producers. The name and voice of an A-lister, meanwhile, helps sell a program and bring in audiences, even if the narrator may never have set foot in the filmed locations and likely has no real knowledge of the animals. The move away from the style of filmmaking Attenborough pioneered marks a wider cultural shift away from experts to celebrities.

Mammals | Official Preview ft Coldplay | BBC America

A focus on environmental issues

Attenborough has been a powerful ambassador, onscreen and off, for urgent action to tackle biodiversity loss, environmental destruction and climate change. At the 2021 United Nations COP26 climate summit in Glasgow, Scotland, he appealed to global leaders, many of whom had flown in by private jet to hear him speak. The new series, too, makes impassioned arguments for humans to urgently solve the question of habitat loss and the need for both humans and animals to have enough space to live in. It’s particularly jarring to see wild elephants marauding through traffic in a town near Victoria Falls, Zimbabwe, a stark illustration of the problem, though it’s also a strange call from the producers to pull their punches and not show the injuries and fatalities that often happen to people and animals in such situations, including animals killed with poison, spears and guns, and through road accidents or run-ins with power lines.

Though Attenborough has a cleareyed view of the fast-escalating predicaments facing animals around the globe, in “Mammals,” he also emphasizes reasons for hope, such as the doubling of the Bengal tiger population across India in recent decades, and the scientists in Patagonia whose tracking of blue whales’ movements has led to the creation of protected areas with less shipping traffic and slower boat speeds. But such efforts are not enough, as Attenborough makes clear: “We’re now aware of the threats we create,” he says in “Mammals.” “Surely, we should now do everything we can do prevent them.”

“Mammals” sounds cautiously hopeful notes. But in our conversation all those years ago, Attenborough didn’t sound very optimistic that humans would turn things around in time. “I’m sure things are going to get worse before they get better, if they get better,” he told me. “They won’t get better in my lifetime, but that’s not very long ahead. I don’t think they’ll get better for 50 to 100 years. I hope they won’t get too much worse, but I fear they certainly will.”

“Mammals” premiered in the UK on BBC One this week and is due to air on BBC America starting this July.