America Released 14 Wolves Into a Valley Ruled by Elk — 20 Years Later, Nobody Expected This

[00:00:09]In the spring of 1909, a 22-year-old government hunter named Aldo Leupold was working in the mountains of New Mexico.

[00:00:17]His job was to eliminate predators from federal land, wolves, cougars, coyotes.

[00:00:23]The federal program called it varmint control. Leupold called it his assignment.

[00:00:31]One afternoon, he and his group spotted a wolf and her pups crossing a river below them.

[00:00:40]They opened fire. The pups scattered.

[00:00:43]Leopold's group reached the old wolf as she lay dying. He wrote about what happened next 35 years later when he finally found the words for it.

[00:00:53]We reached the old wolf in time to watch a fierce green fire dying in her eyes.

[00:01:02]He kept working. The predator program continued.

[00:01:06]By 1926, the last wolf in Yellowstone National Park was [music] dead.

[00:01:12]Leopold spent the rest of his life trying to explain what that green fire had meant [music] to the mountain, to the elk, to the rivers downstream. He died in April 1948. His words were published the following year. It took another 47 years for someone to test whether he was right.

[00:01:34]On January 12th, 1995, a wildlife biologist named Rick McIntyre stood in Lamar Valley, Yellowstone, and watched 14 gay wolves step out of plywood crates into the snow. He brought a notebook. He had no idea he would still be standing in that valley [music] 25 years later.

[00:02:05]The Yellowstone River system drains 35,000 square miles of the northern Rockies. Yellowstone National Park, established in 1872, the first national park in the world, sits at the headarters. 3 and a half thousand square miles of geyser basin, alpine meadow, and river valley. For most of the 20th century, it was managed as a landscape in balance. It was not.

[00:02:36]The grey wolf had been the apex predator of the northern Rockies for 10,000 years.

[00:02:43]When the federal predator control program began in 1915, [music] hunters worked systematically through public lands, Yellowstone included. The program was efficient. The last wolf in the park was killed in [music] 1926.

[00:02:57]What followed was invisible at first.

[00:03:08]Without a predator, the elk population had no reason to move. By the winter of 1994, NPS biologists counted 19,045 elk on the northern range, three to four times what the land could naturally support.

[00:03:26]The elk stood in the flat valleys. They grazed along the river banks for hours without moving on. They had no reason to.

[00:03:38]>> 70 years of that had consequences the park managers could see but could [music] not stop. The willows were gone from the Lamar River. The aspens were not regenerating. The banks were eroding.

[00:03:56]The Yellowstone River, which flows north and supplies drinking water to 106,000 people in Billings, Montana, was carrying more sediment each year. The park had tried to fix this. [music] For decades, it had not worked.

[00:04:15]An elk without a predator does not behave the way an elk is supposed to behave. Normally elk rotate through terrain, grazing briefly, scanning constantly, moving on. That movement is the mechanism by which vegetation recovers.

[00:04:32]Grazed land rests, willows regrow, banks stabilize.

[00:04:38]Without wolves, the elk had stopped moving. They stood in the flat valleys along the river where the soil was soft, the grass thick, the water close, and grazed every day in the same places. The willows went first along the Lamar River. Stands had been grazed to ground level by the early 1990s. No willows meant no beavers. No beavers meant no dams, no wetlands. Water temperatures rose.

[00:05:13]The river without root systems holding the banks in place widened and shallowed.

[00:05:21]In 1944, while managing his Wisconsin farm, Aldo Liupold was finishing the essays that would become a Sand County almanac. [music] In one called Thinking Like a Mountain, he described what he had understood from the dying eyes of that wolf in New Mexico.

[00:05:38]A mountain that has lost its wolves, he wrote, is overrun by deer. The deer eat the slopes down to bare rock. The slopes wash into rivers.

[00:05:52]The rivers run shallow and warm.

[00:05:54]Everything downstream changes. He had seen it in New Mexico. He had come to believe it applied everywhere. He was describing Yellowstone, a place he had never been to measure.

[00:06:10]Aldo Liupole died on April 21st, 1948 fighting a grass fire on a neighbor's property near his Wisconsin farm. A Sand County Almanac was published the following year. The willows along the Lamar River continued to disappear.

[00:06:27]In the winter of 1961, the National Park Service killed 4,39 elk in a single season.

[00:06:37]You got him.

[00:06:39]>> The calling program had been running since the 1920s.

[00:06:49]By 1961, the northern herd had grown large enough that managers authorized one of the largest wildlife reduction operations in American history.

[00:06:59]Television crews filmed it. [music] Newspapers covered it. Congress held hearings. The public called it a slaughter. The program was halted in 1968.

[00:07:16]Over cow call. Where's your cow call? He's going down, guys.

[00:07:22]Nice shot.

[00:07:38]The NPS then shifted to natural regulation. No active intervention. Let the ecosystem find its own balance.

[00:07:48]In a functioning ecosystem with apex predators, this can work. In Yellowstone, which had none, the elk did what populations without limits do.

[00:08:00]From roughly 6,000 elk in 1970, the herd climbed past 11,000 by the mid 1970s and reached 19,045 by 1994.

[00:08:21]planting willows and aspens along the eroded banks. A rangers field report recorded the result plainly. The park could not plant trees faster than the elk could eat them.

[00:08:34]In 1987, the US Fish and Wildlife Service formally proposed reintroducing grey wolves. What followed was 8 years and one of the largest environmental impact statements in American history.

[00:08:49]160,000 public comments submitted. 3/4 of Americans pled supported the reintroduction.

[00:08:56]Wyoming and Montana ranching associations opposed it. Several members of Congress opposed it. The legal and political debate ran until January 1995.

[00:09:07][music] After four decades of failed programs, 8 years of process, and 47 years since Aldo Leopold had written what needed to happen, the answer arrived in a plywood crate. 14 wolves. That is how many it took to begin reversing what millions of dollars and decades of active management had not.

[00:09:40]On January 12th, 1995, Rick McIntyre was in Lamar Valley when the first eight wolves arrived from Jasper National Park in Alberta. He was a wildlife biologist recently assigned to the Wolf Project.

[00:09:54]He brought a field notebook. He did not know that notebook would become a 25-year daily record. More than a 100,000 individual wolf sightings, the most sustained continuous wildlife observation in the history of the park.

[00:10:12]The first thing he noted was not a kill.

[00:10:15]Within 2 weeks of the release, the elk were moving differently. In the flat valleys, where they had grazed undisturbed for 70 years, standing for hours in the same places, eating without scanning, they were now on the move.

[00:10:30]Shorter intervals at valley floors, more time on higher terrain, more time with their heads up.

[00:10:40]The wolves had not killed many elk in 2 weeks. They hadn't had time.

[00:10:49]In 2001, ecologists Landre Hernandez and Altonorf published research in the Canadian Journal of Zoology measuring elk vigilance behavior across wolf present [music] and wolf absent zones in the park. Female elk in wolf territory spent significantly more time scanning and significantly less time grazing in riparian areas, the valley floors where wolves most effectively hunt.

[00:11:20]Landre called it the landscape of fear.

[00:11:23]Wolves do not need to kill every elk.

[00:11:26]They only need to exist.

[00:11:33]Elk and wolves co-evolved in North America for 10,000 years. That fear response is not learned. It is encoded.

[00:11:42]70 years without wolves had not erased it.

[00:11:52]In March, six more wolves arrived from British Columbia. Among the 14, McIntyre began tracking a young male he designated wolf 21.

[00:12:04]Wolf 21 would become one of the most observed individual animals in the history of field biology.

[00:12:10]what he did over the following decade and what eventually happened to him.

[00:12:15]McIntyre recorded in daily entries he has never stopped writing.

[00:12:25]What happened to the landscape, the willows and the rivers begins with where the elk were no longer standing.

[00:12:34]When the elk stopped standing in the valleys, the willows started to grow.

[00:12:39]Robert Besta and William Ripple at Oregon State University had been measuring willow heights along the Lamar River since 1998, 3 years after the wolves arrived. In that year, the tallest willows stood 75 cm. By 2002, they stood 200 cm. In the years that followed, some stands exceeded 3 m. Research tracking the same zones over two decades found substantial willow recovery in areas where elk movement had most dramatically shifted.

[00:13:12]The elk hadn't disappeared. There were still thousands of them. They had simply stopped standing in the places where willows grow.

[00:13:24]As the willows recovered, beavers returned. In 1995, there was one active beaver colony in Yellowstone. By the early 2020s, researchers had documented nine beavers eat willows and build dams. Each dam creates a pond. Each pond becomes a wetland, habitat for otter, muskrats, ducks, fish, and amphibians. Beaver ponds raise the water table in surrounding soil, supporting riverbank vegetation through summer drought.

[00:14:05]Wolves were also suppressing coyote populations. Fewer coyotes meant more rabbits and rodents, drawing more hawks, foxes, and badgers. Ravens followed wolf kills for carcasses. Eagles did the same. Grizzly bears found wolf kills as a food source and began ranging more widely through the recovering landscape.

[00:14:29]14 wolves had entered a valley and [music] by doing what wolves do, hunting, moving, dying, reactivated a chain of relationships dormant for 70 years. Each link had been waiting for the right conditions. The wolves provided them.

[00:14:51]And then the geomorphologists arrived with a finding no one had fully predicted. Researchers measuring the Lamar River and its tributaries found that the channels had changed course. In some sections, channel width had narrowed between 1990s baselines and post205 measurements.

[00:15:12]Riverbanks that had been bare and collapsing now had root systems holding them in place. Where banks held, channels deepened. Deeper channels created pools.

[00:15:27]pools restored habitat for cutthroat trout, nearly absent from sections of the Lamar in the 1990s. By 2005, the trout were returning.

[00:15:41]The wolves did not touch the river, but the river had been waiting for them.

[00:15:46]Aldo Leupold had [music] written that without wolves, the deer eat the slopes and the slopes wash into the rivers. He had written it from observation and inference with no measurements to offer.

[00:15:58]The river 60 years later was providing the measurements.

[00:16:10]Within months of the 1995 reintroduction, ranchers in Wyoming, Montana, and Idaho reported wolves attacking livestock. Between 1995 and 2008, verified kills included cattle, sheep, and horses across the northern Rockies. The federal government paid compensation through Defenders of Wildlife and later the USDA for confirmed losses.

[00:16:43]>> [music] >> Ranching associations argued the verified numbers were a fraction of actual losses. "You can't put a radio caller on every calf that goes missing," said one Wyoming rancher in an interview with the Associated Press in 2004. "All I know is what my numbers looked like before and what they look like now." The debate over verification methods never resolved.

[00:17:12]In 2003, proposals to strip wolves of Endangered Species Act protection began moving through the courts. In 2011, Congress passed a budget writer removing ESA protections for wolves in Idaho and Montana. The first time in the history of the act that Congress had used a budget measure to delist a specific species, bypassing the standard judicial process. Hunting seasons opened within months.

[00:17:52]In Idaho, hunters killed several hundred wolves per year in the years following delisting. The Druid Peak Pack, which McIntyre had watched grow to 37 members by 2001, possibly the largest wolf pack ever recorded, declined to fewer than five animals by 2010.

[00:18:14]Yellowstone has no fence. A wolf that follows elk into Montana crosses an invisible administrative line. The majority of Yellowstone wolves killed by humans over the program's history have died outside park boundaries in legal hunts.

[00:18:39]Two wolves McIntyre had been watching Wolf 21 since 1995.

[00:18:45]Over nearly a decade of daily observation, he recorded something he found remarkable. Wolf 21 had never once been seen killing a defeated rival male.

[00:18:56]When challengers lost and submitted, he let them walk away. He had twice taken in orphaned pups from rival packs.

[00:19:11]On February 2nd, 2004, Wolf 21's mate, Wolf 42, his partner for 10 years and co-leader of the Druid Pack, was killed by the rival Molly's pack on Specimen Ridge.

[00:19:29]Wolves were heard howling across Lamar Valley for days afterward.

[00:19:40]In April 2004, researchers found Wolf 21 dead beneath a tree on a ridge above his home territory. He was 10 years old. Old for a wild wolf. McIntyre wrote four words in his field notebook.

[00:19:58]In December 2012, a wolf researchers designated 06, alpha of the Lamar Canyon Pack, the most photographed wolf in Yellowstone, was legally shot by a hunter on private land 6 miles from the park boundary.

[00:20:15]Her death was reported in [music] the New York Times. Her mate was seen wandering Lamar Valley alone for weeks afterward. The Druid Peak Pack was gone.

[00:20:26]But what the wolves had started in 1995 could not be undone.

[00:20:36]30 years after January 1995, Yellowstone holds approximately 100 wolves across nine packs. The northern elk herd peaked at 19,045 in 1994. [music] It declined significantly in the years that followed, a number that continues to be studied and debated.

[00:21:00]Wolf advocates pointed to the ecological recovery. Critics noted that drought, grizzly bear recovery, mountain lions, and hunting outside the park all contributed alongside wolves.

[00:21:13]By 2018, the herd had partially recovered. Scientists who study the northern range consider the current level closer to what the land can sustainably support than the 19,045 peak. That question remains actively researched.

[00:21:33]In 2006, economist John Duffield at the University of Montana estimated that wolf watching ecoourism generated $ 35.5 million per year for gateway communities near Yellowstone. By 2021, that figure had grown to $82.7 million.

[00:21:52]Total livestock compensation paid to ranchers from 1995 through 2010 was estimated between $3 and $5 million.

[00:22:01]Wolf watching revenue in a single year exceeded the entire 15-year livestock payment total. It is worth being honest about what the science does and does not say.

[00:22:15]William Ripple, whose research with BESHA established the trophic cascade framework for Yellowstone, noted in a 2019 review that riparian effects were real but more spatially variable and complex than early accounts had suggested. Climate shifts, predator recovery, and hunting pressure outside the park all contributed to changes in elk distribution. The cascade happened.

[00:22:40]Its precise magnitude at the river level is still being measured.

[00:22:47]That is what 30 years of rigorous field science looks like. It is not a clean line from cause to effect. It is a system responding slowly and unevenly to conditions restored. Rick McIntyre still goes to Lamar Valley. He still brings a notebook. Aldo Leupold shot a wolf in New Mexico in 1909 and spent the rest of his life trying to explain what he had seen in her eyes. He died in 1948, 47 years before the wolves returned to Yellowstone. He never saw what he was asking for.

[00:23:25]The Lamar River runs cleaner and deeper than it did in 1994. The willows are back. The beavers are building. McIntyre is still watching. The mountain, it turns [music] out, had been waiting for someone to listen.

[00:23:44]Yellowstone is not the only place where this question is being asked. In Scotland, the debate over wolf reintroduction has continued for 30 years. In Portugal, wolf populations recovering along the Spanish border are being studied for similar cascade effects. In Colorado, grey wolves were reintroduced in 2023 for the first time in decades. The results are still being measured.

[00:24:12]The politics are never simple. The ecology is never as clean as a single story makes it. But Aldo Leupold asked the question in [music] 1944.

[00:24:22]Rick McIntyre has been watching the answer since 1995.

[00:24:26]If you're watching from somewhere this debate is happening or somewhere it should be, leave a comment below. We read them.