How Much Longer Can These Cold-Loving Birds Last in the Rapidly Warming Rockies?

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The dark profiles of the Rocky Mountains loom against a star-studded sky. Amy Seglund, a species conservation program manager for Colorado Parks and Wildlife, hikes up a steep trail inlaid with rocks stacked like stairs into a high-elevation basin. As she climbs, her headlamp beam falls on smaller and smaller pines and spruces, then willow thickets, and eventually clumped grasses and plants with leaves and petals smaller than buttons.

In the dim blue light of dawn, Seglund strides onto the alpine tundra, holds up a boombox-like machine, and blasts the raucous, chattering cry of a male Southern White-tailed Ptarmigan. The birds are masters of camouflage—finding one just by looking is unlikely to impossible—so scientists use this device to call them in. During breeding season, males of this grouse species will rush out at that call, ready to defend their mates. With breeding season over by this late August morning in 2023, some birds may no longer bother, making them hard to spot. But finding ptarmigan here at all is becoming less reliable.

Temperatures historically remained cool in these mountain basins. Snow lingered late into summer, and frequent rainstorms replenished streams and wetlands. Now the alpine zone is growing warmer, and familiar patterns of snow and rain are fragmenting. Seglund is among those trying to find out just how well ptarmigan can adapt to these changes.

Between territorial calls, Seglund plays a chick’s piteous cheeping, trying to draw out females. She switches off the device and listens, but only silence follows. Nearly two hours pass before Seglund receives a reply. She looks up to glimpse the white underside of a male ptarmigan flying down from a ridgeline. Then five more birds dash by. Researchers began studying ptarmigan in this basin in the 1960s, so it was one of the first places she started surveying more than a decade ago, when biologists became worried about how the birds would fare in a warming world. Males and females without chicks form flocks in late summer, and initially, Seglund sometimes encountered groups of around 30. Historic literature suggests sizable flocks were common. But in autumn 2021, she found only a handful of birds.

Lower numbers aren’t her only concern. She’s also seen males—typically vocal about their territories but not physically aggressive—charging and knocking one another off rocks. The squabbles might be linked to a widening gap Seglund has observed between numbers of males and females, which is leaving more males without a mate. Such a disparity, she says, “is usually an indication things aren’t going well for a bird.”

To find out for certain, since 2011 field researchers have monitored ptarmigan in Colorado’s high country most summers. Meanwhile, biologists in New Mexico are tracking ptarmigan at the southernmost portion of their range, where the birds are more exposed to the climate-driven challenges creeping north up the spine of the Rockies. The efforts aim to better understand the limits ptarmigan might soon be up against and what, if anything, humans can do to help them survive.

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hite-tailed Ptarmigan were built for a wintry world. Their densely feathered feet act like tiny snowshoes. Thick plumage insulates the birds in fierce cold and deep snow. Those feathers molt from mottled chocolate, caramel, and cream in summer to white in winter, matching the landscape so well that ptarmigan can hide in plain sight—their primary defense against predators including weasels, foxes, and raptors. The same goes for Willow and Rock Ptarmigan, which are found at lower elevations than their White-tailed cousins and occupy a vast Arctic and subarctic terrain. The three species constitute the only genus of bird to turn white seasonally.

Through winter they burrow into snowbanks, feeding on willow buds and twigs and gaining weight in a season when most animals struggle not to lose it. But so much insulation makes overheating easy: At just over 70 degrees Fahrenheit, ptarmigan have been seen cooling themselves in snowbanks.

The bulk of White-tailed Ptarmigan habitat is found in western Canada and southeastern Alaska and reaches down into Montana and Washington. But the southern subspecies persists in the high country through Colorado, New Mexico, and historically Wyoming. They may have evolved from ptarmigan that moved south with glaciers during an ice age, then became isolated in colder, wetter conditions above 11,000 feet as the glaciers retreated.

Those conditions are changing rapidly. Alpine habitats—wind-scoured heights where brief growing seasons deter trees and wildflowers hug the ground—are among the fastest-warming on the planet. Average annual temperature in Colorado’s Rocky Mountain National Park has risen 3.4 degrees Fahrenheit over the past century. Snow is melting faster, summers are growing longer, and water sources are drying up. Even as far north as the southern Yukon, the species and its alpine strongholds are suffering from climate change. 

Mountaintops are essentially islands of one type of habitat surrounded by an ocean of something else, says David Luther, an ecologist at George Mason University. That isolation puts creatures that live there at greater risk from diseases, predators, and storms. And now, not unlike seas rising to swallow coastal habitat, higher temperatures are pushing the tree line further up mountainsides, shrinking the zone with suitable conditions for the birds. Eventually ptarmigan could lose their high-peak homes altogether—unless they can find strongholds, such as cooler north-facing slopes, and hang on. “That’s the big hope: that animals will have opportunities to go to those microclimate refugia and persist at least long enough to be able to adapt to the new circumstances,” Luther says. “We can’t just cluster them all in the coldest place we can find.”

As early as 2006, researchers flagged climate change as the greatest threat to ptarmigan in the Rockies. In 2010 the nonprofit Center for Biological Diversity detailed those concerns in a petition for the U.S. Fish and Wildlife Service to consider them for threatened or endangered status. Colorado holds the largest Southern White-tailed Ptarmigan population and the greatest share of suitable habitat in the Lower 48, so the FWS asked state wildlife biologists, including Seglund, how the birds were doing. 

Beginning in 2011 she and her team counted ptarmigan, banded more than 600, and radio-collared 126 individuals across the state. Their report, finalized in 2018, generally found the population stable and well dispersed. Soon after, the FWS likewise concluded Southern White-tailed Ptarmigan were at low risk.

“And then it all went to hell,” Seglund says. 

Seglund spent the next three summers studying Brown-capped Rosy-Finches, another vulnerable alpine species. She noticed that instead of needing hats and gloves, she and her colleagues were comfortable in T-shirts and hot enough to swim in frigid lakes in September. Afternoon rainstorms all but vanished. She kept an eye out for ptarmigan and seemed to spot fewer, most of them male. At times they dropped to lower elevations, seeking shade below dense willows. Despite the temporary reprieve, they were panting.

By 2021, Seglund was concerned enough to resume ptarmigan surveys. What her team has discovered is troubling. Counts in 2011 found males and females in almost equal numbers—fitting for a monogamous species. But a decade later, the split was 67 males to 33 females, and in 2022, 75 to 25. “The signal has just changed so drastically,” Seglund says. If hen numbers continue to plummet, the whole population could follow. Past research has found that female ptarmigan, stressed by raising young, tend not to live as long as males. Now Seglund is concerned that heat may be further abbreviating their lifespans. 

That link hasn’t yet been established, but climate change seems to have its fingerprints all over another trend: At a pair of long-monitored Colorado sites, ptarmigan breed 9 to 12 days earlier than they did when research began in 1968, according to a 2016 study. So far their breeding still seems to align with when insects and plants emerge, but if hatching becomes mistimed, chicks could go hungry.

It’s not clear how flexible ptarmigan will be in adapting to higher average temperatures, longer strings of hot days, or increasingly extreme weather, says Cameron Aldridge, a U.S. Geological Survey ecologist who coauthored that study: “We don’t know where the thresholds are.” Aldridge has seen early springs strand birds in winter-white plumage on brown tundra. “The science isn’t telling us we’re going to lose ptarmigan next year,” he says. “The science is telling us we should be concerned that if climate change continues, we’re not totally certain if these birds are going to be able to cope.”

So far, USGS biologist Gregory Wann, another coauthor, says he’s seen ptarmigan adjusting how they use the landscape, moving not off mountain tops but into wet, shady crevices among boulders or onto ice fields, where temperatures are 10 to 20 degrees cooler. Elsewhere, however, circumstances have compelled researchers to consider whether some habitats have become too hostile for ptarmigan to endure.

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ill Taylor sits in a truck parked in the shade at a municipal airport in Las Vegas, New Mexico, his eyes fixed on the runway. The moment a twin-prop plane touches down, he cranks on the truck’s air-conditioning. The only passengers on the flight are five ptarmigan that biologists captured this morning in Colorado, outfitted with radio collars, and bundled into cardboard pet carriers. It’s September 2023 and these are among the first of 23 birds that will be transplanted this month. Taylor, northwest regional wildlife biologist for the New Mexico Department of Game and Fish, is tasked with keeping them cool as he transports them to a trailhead in the Sangre de Cristo Mountains.

With the featherweight boxes secured in the truck’s back seat, Taylor drives up into the peaks to a campsite ringed in spruce, fir, and aspen. As evening descends, he moves the birds to the truck bed—in a dog kennel to protect them from skunks, foxes, or owls that might come looking for a snack—and listens gladly to them rattling their boxes. “Sounds like they’re real strong, healthy birds,” he says.

In the morning, as peach rims the sky, he straps the boxes to backpack frames that two other wildlife biologists, Marina McCampbell and Jena Nierman, gently shoulder. The pair sets off on a trail that climbs about four miles to a ridge in the Pecos Wilderness, home to the warmest and most isolated archipelago in the bird’s range. As they ascend, a few downy feathers drift out of the boxes. A dark eye peers through an air hole. The three ptarmigan Nierman carries thump constantly, shaking the boxes against her back. “It’s like a little motivation to keep going,” she says.

New Mexico’s mountains host wildlife and plants otherwise bound to more northern latitudes, including White-tailed Ptarmigan. “No better proof could be found of the valuable diversity of climate of the Southwest than the presence of this purely Arctic bird on the high peaks,” wrote conservation icon Aldo Leopold, once supervisor of the surrounding national forest. Fossil evidence suggests that ptarmigan lived even farther south thousands of years ago, but by 1980 biologists found only a handful statewide. In 1981, attempting a recovery, wildlife managers moved 43 ptarmigan from Colorado to New Mexico. That population persisted for about three decades before it, too, faded out. By 2018 the state game and fish department considered the birds functionally extinct in New Mexico.

Now department biologists are trying to rebuild the population. In 2021 they moved 24 ptarmigan from Colorado to New Mexico. They planned to bring another round the following year, but a wildfire delayed those transplants, some of which McCampbell and Nierman are releasing today. The hope is that the new arrivals will form a self-sustaining population and that monitoring them will reveal thresholds for the birds’ survival. 

Tasked with keeping tabs on the transplants is James Lee, a graduate research assistant with New Mexico State University. Searching ridgelines in late August 2022, he found fewer ptarmigan than expected, and there was no sign of chicks—not encouraging, but the wildfire might have been to blame. Today he joins up with McCampbell and Nierman as they head up a trail he’s hiked several times a week since May. 

After an hour, a rocky, wind-scoured ridge that marks an entry to some of New Mexico’s highest peaks comes into view; in another hour, the researchers are atop it. The official end of summer is still a few weeks away, but it’s already autumn up here. The short grass is crisp, and alpine avens—wildflowers with green, fernlike fronds and yellow blossoms in summer—are tinged red. That’s a favorite ptarmigan food, Lee says, “like popcorn.” McCampbell lifts the first ptarmigan from a box, and it bursts from her hands. As she opens the flap over the second one, it launches in a flutter. “They’re spring-loaded,” Lee says, watching as the next two take off. The last ptarmigan lingers to preen ruffled feathers and scratch its chin with a foot. At noon a text message announces that more birds have been caught in Colorado. The team will hike down to the trailhead to collect the new arrivals and do it all again tomorrow. 

Seglund isn’t convinced that moving the birds to New Mexico will be any more successful this time around; the state never held a sizable population, and its already marginal and isolated habitat likely can’t sustain ptarmigan for long, she says. She agreed to the plan only with tight limits set on the numbers—no more than two females or five birds total from any one site—to protect Colorado’s populations.

But translocations have worked in the past. Seglund describes wildlife agencies swapping animals like trading cards in the 1970s, including 55 ptarmigan sent from Colorado to Utah’s Uinta Mountains in 1976. She horse-packed 17 miles to check on them in July 2024, and a ptarmigan promptly responded to the first call she broadcast. Likewise, birds that were moved to California in 1971 and ’72 have survived and spread. With climate change, the idea of relocating wildlife to better habitat, regardless of where they used to live, has gained favor. In 2023 the FWS revised regulations to allow moving an endangered species to new habitat if its native range is no longer suitable, a process often called assisted migration or managed relocation.

New Mexico law requires wildlife managers to try to recover vanishing native species, but that’s not the only reason to give it a shot, says John Bulger, terrestrial recovery coordinator for the state game and fish department. “If there comes a point where you just have to say, ‘Well, they can’t live here anymore,’ fine,” he says. “But we can’t and shouldn’t just speculate.” Genetic studies suggest that ptarmigan can adapt to local climate and food sources; scientists even found evidence of a heat-tolerant gene among ptarmigan from New Mexico, though it’s not clear if any survivors still carry that adaptation.  

In spring 2024, Bulger flew over New Mexico’s White-tailed Ptarmigan habitat to scan for beeps from radio collars. He found 23 birds from the two rounds of translocations. Snow fell late into spring, so it was mid-June before the trail was clear enough to hike to that ridgeline, but he liked what he found when he finally got there. Ptarmigan had spread out over most of their core historic range. Three females were nesting. 

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Colorado field technician needs to be in ptarmigan habitat before sunrise, so training days begin in the dark. On a June morning in 2024, nine recruits do their best to keep up with Seglund as she hikes into an emerald basin threaded with waterfalls in the San Juan Mountains. She coaches them on spotting ptarmigan and on safely navigating the complex terrain. Her sure-footed and steady pace speaks to summer after summer spent up in the alpine.

Between now and September they’ll visit about 60 plots. A day’s work might involve hiking 20 miles over multiple mountain passes, post-holing through snow, bushwhacking through willows, and dodging thunderstorms. When the trainees spot a bird, they record its habitat, such as a rock outcropping at 12,000 feet with one scrubby willow and a jeep road nearby. 

Noting roads and other signs of human disturbance matters because there’s more troubling ptarmigan than warmer weather. Snowmobilers, snowshoers, and backcountry skiers can disturb roosting birds and trample snow they burrow into for food and shelter. Hikers and their dogs in summer can also flush females off nests or away from chicks. And while Colorado Parks and Wildlife considers ptarmigan a vulnerable species, hunting is still allowed. What the field crew finds could prompt calls for public land managers to steer recreationists elsewhere or changing hunting regulations.

The summer 2024 fieldwork findings were mixed. Sex ratios were not as skewed, and flocks were a little bigger, but the birds were missing from more places than in past years. Now Seglund is gathering researchers to launch a more intensive investigation, which could start as soon as next summer. Conservationists will be watching as they consider whether to revisit protected status for the species. “It just seems like we’re going to have to do this for a while to really figure out what’s happening,” Seglund says. 

The survey crew spends that first June day climbing ridges and circling cobalt lakes streaked with ice, searching, playing calls, and waiting. Males come screeching in, but none seems to have a mate. Finally, in early afternoon, they follow a piercing reply, rock-hopping across a bog to a lakeside knoll where a male ptarmigan perches. Two field technicians edge near it; then one looks up at Seglund and flashes two thumbs up: They’ve also found a female.

Such a find would have been unremarkable when Seglund started her surveys. “Now,” she says, “it seems like a big deal.” She and the others sit on an outcropping as the hen creeps forward one densely feathered foot at a time, emerging enough to show her handsomely speckled sides. When she flies over a sliver of snow, the crew murmurs in amusement. She’s not really a rare bird, but the chance to watch her feels precious. 

This story originally ran in the Winter 2024 issue as “Elevated Risk.” To receive our print magazine, become a member by making a donation today.