The Mt. Graham red squirrel, an endangered subspecies of the American red squirrel is in increased danger as devastating wildfires diminish their population.
Sean Logan, The Republic

The Mt. Graham red squirrel population plummeted from 252 to about 35; experts say fire or predators could doom the species.

CORONADO NATIONAL FOREST — In November, the colors in the forest are still changing.

Scant sunlight dances on the green and yellow leaves just feet from fallen trees with blackened trunks, charred from a wildfire that could still wreak havoc on the forest’s ecosystem, though it was contained months ago.

Bobcats slink down the mountain’s side, wild turkeys bob their heads as they walk, and Abert’s squirrels munch away on pine cones, filling the forest with their own unique calls and rituals.

The landscape is diverse and so is the wildlife.

But an ever-increasing ensemble of threats — climate change, raging wildfires and migratory predators — have greatly thinned out some animal populations and, in some cases, could push already imperiled species to extinction.

Species dealt a potentially deadly blow

At greatest risk is the Mount Graham red squirrel, an endangered subspecies of the American red squirrel. 

The lightning-caused Frye Fire burned across 48,000 acres in June and July, scarring the squirrels’ high-elevation habitat and dealing the species a potentially deadly blow.

Their population, which measured 252 last year, is down to an estimated 35, according to an annual survey conducted by the Arizona Game and Fish Department, Coronado National Forest, U.S. Fish and Wildlife Service, Arizona Center for Nature Conservation and the University of Arizona.

Conservationists and researchers fear a bleak future for the squirrels and the surrounding ecosystem, which could suffer a series of setbacks without them.

“In an area where you may have had 10 squirrels, now there’s three,” said Melissa Merrick, a UA senior wildlife biologist. “We really don’t know how that (ecosystem) will change if they’re no longer here.”

Merrick works with the squirrels for multiple days each week, tracking their locations, occasionally weighing them and checking their reproductive status.

For some of the wildlife, this is permanently home. The Pinaleño Mountains of southeast Arizona are part of the Coronado National Forest’s sky islands — towering peaks surrounded by deep swaths of desert.

Many animals native to the sky islands, including the endangered Mt. Graham red squirrels, cannot survive in the harsh conditions to the surrounding desert.

More than experts concerned about squirrels

At 10,000 feet, Mt. Graham’s verdant landscape is flecked with the remains of fallen trees. Cavernous holes in the ground show where their trunks once stood, where their roots once stretched.

The Frye Fire came in an intense wildfire season for Arizona and took more than a month to be fully contained. Over the summer, Gov. Doug Ducey declared a state of emergency while 14 wildfires raged.

The concerns for the squirrels extend beyond experts like Merrick, who has a hands-on relationship with them.

Sen. John McCain, R-Ariz., last month wrote letters to the Arizona Game and Fish Department and the U.S. Fish and Wildlife Service, asking for increased attention to the squirrels’ future.

“Only an estimated 590 acres of suitable squirrel habitat remains,” his letter to Fish and Wildlife says. “By some accounts, the Mt. Graham red squirrels may not survive this winter. Squirrel experts believe it will take significant human intervention to help the Mt. Graham red squirrels survive this winter.”

The Frye Fire, whose scars reach like stretch marks through the forest’s foliage, signified a setback for the squirrels, but they have suffered fires before.

“We do know that squirrels are resilient … this forest has burned in the past,” Merrick said. “And we know the squirrels survived those experiences.”

Winter poses the next threat.

Birds, particularly the Mexican Spotted Owl, Red-tailed Hawk and the Northern Goshawk, prey on the squirrels. This winter, it would only take a few more migratory visitors than usual to thin out the vulnerable squirrel population or obliterate it.

“There is some room for optimism, but also a lot of room for concern,” Merrick said. “I don’t want to paint too rosy of a picture.”

In the wild

Merrick holds a radio in one hand, listening.

She points a large, tuning fork-like rod to the east, to the south, to the north. She listens.


She uses the equipment to get a signal from radio collars that 11 squirrels wear. Each collar is tuned to a different frequency.

When Merrick sets her radio to the same frequency, pointing the rod toward the squirrels produces a beep on her radio. The more consistent the beeps, the closer she gets.

It doesn’t take her long to find a squirrel. She looks for a tag on the squirrel’s ear and, based on the information she has, takes out her waterproof notebook and makes a note of it.

Often, the squirrels are perched on trees, devouring conifer cones, building nests or bringing supplies to their middens — piles of cones they use to keep all their food in one place.

Some squirrels like their middens to be towers, piles of cones reaching upward. Others bury food in cavities caused by the Frye Fire.

Putting the food underground acts as a sort of natural refrigerator, Merrick says.

“Some of them are very organized, some are not,” she says, hiking up Mt. Graham to check in on the next collared squirrel. “Just like people.”

The squirrels are highly territorial. At one point during Merrick’s trek, an Abert’s squirrel wanders through the forest, only to be met by a screeching red squirrel, hurriedly scurrying down the tree to give chase.

Merrick watches it all.

When the squirrel climbs back up the tree and gives another screech, it’s a warning to others.

“They do that several times a day,” she says. “Just to announce, ‘I own this territory.'”

Although Merrick sometimes does the squirrel check-ins by herself, she’s part of a larger group of UA researchers, professors and PhD students who regularly come into the Pinaleño Mountains to study the animals.

John Koprowski, UA professor and associate director of the School of Natural Resources and the Environment, took the group over in 2000 and shares the team’s findings on his website.

“On Mt. Graham, they reproduce about as much as other squirrels do, but the mortality rate, their survivorship, is really, really low,” he said. “It’s about half of what it should be.”

The squirrels were thought to be extinct in the 1960s, until they were rediscovered in 1972.

Fifteen years later, in 1987, they were listed as endangered.

Their population peaked at about 550 in the late ’90s, according to the Game and Fish Department.

Biggest challenge is their ability to survive

Koprowski is concerned the squirrels will fall to predators this winter. If the forest loses all its squirrels, only a handful — in captivity in Phoenix — will remain.

There doesn’t seem to be a solution for the problems predators pose, at least not a simple solution. The Mexican Spotted Owl is classified as threatened.

“Anything you do to protect the endangered species, you could argue that it’s at the expense of the threatened species,” Koprowski said. “So it’s a little complicated.”

The squirrels are bookended by danger anywhere they go in the wild. The mountains they live in are part of the 70,000 square-mile sky islands that spill over from Arizona into New Mexico.

Many animals are native to the sky islands and some exist outside of them. Others, like the red squirrels, could die if they tried to venture out of their habitat. Since their population is stuck there, they’ve experienced generations of inbreeding.

They’re confined. They’re chased by aerial predators. They’re only able to mate for one day a year in the wild, when a female is in estrus and a male’s testes have temporarily descended.

“Their ability to survive,” Korpowski said, “is their biggest challenge.”

In captivity

It’s quiet.

It’s quiet because it has to be.

Squirrels rest on tree limbs, replete with foliage, and dart up and down a branch. Back and forth. Eating, sitting, occasionally making chatter.

They do it all in a cage.

The Phoenix Zoo in 2014 launched a pilot captive breeding program with six Mt. Graham red squirrels in hopes of breeding and releasing them into the Pinaleño Mountains.

The squirrels now live in the zoo’s conservation center, led by its director of conservation and science, Stuart Wells.

In the wild, the squirrels are believed to be capable of mating one day each year, Wells said. And on that day, they only have a few hours.

The males, whose testes descend for a few months out of the year before retreating into the body, need that to line up with female squirrels’ cycles. They’ll chase females through the forest in hopes of mating, a practice that could be deadly in the conservation center’s limited space.

“If they’re together the rest of the time of the year, there’s a lot of aggression,” Wells said. “In the field … she can run up a tree, she can just run as far as she can. She can get away, usually.”

But in the lab, they only have a few dozen square feet to run around, he said.

Although it’s anecdotal at this point, Wells and his team have found the female squirrels in captivity cycling about once every 20 to 25 days — a potential exponential growth in eligibilty.

“If that is true, that means the breeding program could be better,” Wells said. “That’s better than one day.”

The center isn’t open to the public and the few people who do come through here — Wells and his staff, mostly — try to be as quiet as possible. The squirrels will show signs of discomfort once noise reaches around 70 decibels, about as loud as a vacuum cleaner or alarm clock, Wells said.

The last time someone took photos near a squirrel, the sound of the shutter clicking had them agitated for about a week, he said.


Show Thumbnails

Show Captions

So far, the zoo has only had one successful breeding, but it didn’t produce offspring. One of the female squirrels also died while in captivity — potentially from stress, he said.

Limited space and restrictive reproductive cycles are roadblocks enough, but the squirrels’ lifespans can pose problems for them, too.

In the wild, they can expect to live about two years, Wells said. In the conservation center, two of the males are coming up on their eighth birthdays.

“Their predation levels are high in the wild,” he said. “That’s a real critical point for the recovery of these guys now that the fire has affected the canopy cover even more so. I think it doubles the importance of this program.”

Squirrels’ future in limbo

In cages and in the wild, the squirrels face an uncertain future. Maybe predators wipe out the Pinaleño population this winter. Maybe the captive population all die of natural causes without ever having offspring.

Or, maybe the breeding program has success and new squirrels are introduced to Mt. Graham. Maybe there aren’t more predators this winter and the squirrels are able to stay safe in the 10,000-foot elevation habitat.

From Merrick, the UA biologist, to Wells, to officials with Game and Fish, there is a small level of optimism, however cautious.

“We’re fortunate to have the Endangered Species Act to help us keep species intact. Regardless of what we do sometimes, we’re going to lose some,” said Steve Spangle, U.S. Fish and Wildlife Service field supervisor. “It’s unfortunate.”

Officials from the Arizona Game and Fish Department, U.S. Fish and Wildlife Service, Phoenix Zoo and Coronado National Forest have a plan, but they say it’s outdated.

Fish and Wildlife put out the Pinaleño Ecosystem Restoration Project — officials begrudgingly refer to it by its unsavory abbreviation, PERP. It provides guidance for restoring the mountain range’s ecosystem.

The agency also put out the Mount Graham Red Squirrel Recovery Plan, which is aimed specifically at the subspecies’ future. It’s originally from 1993, more than a decade before the 2004 Nuttal Fire and more than two decades before this year’s Fry Fire.

Although the document dates back some 24 years, there is a 2011 revised draft. Officials say it will need to be updated further because of the Frye Fire’s effects.

The agencies have specific steps in mind for preserving the squirrels, including using Lidar — a radar-like system that uses lasers — or satellite imagery to find unburned or barely burned areas where squirrels might move.

“When you’re dealing with that small of a population, any small things can have big changes for it,” said Tim Snow, a terrestrial wildlife specialist for Game and Fish.

Game and Fish, Fish and Wildlife, the Phoenix Zoo and UA are all working together on potential solutions.

Among the possible next steps for the forest are:

  • Partnering with U.S. Forest Service to re-seed and reduce fuels in old squirrel habitats.
  • Supplemental feeding through the winter at middens with moderate or severe burns.
  • Assist with identifying middens in need of insect pheromone treatments to prevent or reduce insect infestations.
  • Identify potential translocations using White Mountain squirrels and identify funding to assist with any potential translocations. 
  • Reduce non-native squirrel populations in the Pinaleño Mountains.
  • Find methods to create new middens.

‘This is what you call dire straits’

In addition to the two fires, multiple insect outbreaks and drought played a hand in dwindling their population, U.S. Forest Service spokeswoman Heidi Schewel said in an email to The Republic.

She said the Forest Service late last month placed four feeders in the squirrels’ habitat and may modify them. Modifications would prevent other animals from using them, she wrote.

Even though officials have research and the PERP to offer guidance, Spangle is concerned another unpredictable event, like the Frye Fire, could devastate the red squirrels.

“We have a very small population size in a single geographic area,” he said. “And as we saw by this fire, those kinds of populations are extremely vulnerable to unforeseen events.”

While some are optimistic about the squirrel’s chances, Spangle is pessimistic. He’s grateful for the high-profile support, from people like McCain, and hopes that will bring more attention and more resources to help save the squirrels.

But the facts remain: They’re endangered, and predators are coming.

“I am not at all optimistic,” he said. “This is what you call dire straits.”

Environmental coverage on and in the Arizona Republic is supported by a grant from the Nina Mason Pulliam Charitable Trust. Follow the azcentral and Republic environmental reporting team at OurGrandAZ on FacebookTwitter and Instagram.

What it costs to save a squirrel

Any effort to help the Mt. Graham red squirrel will require money. 

Jeff Humphrey, Fish and Wildlife public outreach specialist, said all the agencies working with the squirrels need to identify funding for several steps, including:

  • $30,000 for four new enclosures at the Phoenix Zoo.
  • $40,000 per year for at least six years to pay a full-time Phoenix Zoo staff member dedicated to breeding the squirrels.
  • $9,000 for one year, then $2,500 per year for at least five years for a part-time intern at the Davee Center for Epidemiology and Endocrinology at the Lincoln Park Zoo to research fecal samples for steroids.
  • $6,500 for a soft-release enclosure at the Columbine Administrative Site in the Pinaleño Mountains to acclimate captive-born squirrels before completely releasing them into their natural habitat.
  • $80,000 for a two-year study to determine methods for translocating squirrels to the White Mountains, using White Mountains red squirrels as surrogates.
  • $300,000, which may change, to enhance Mt. Graham red squirrels by planting trees in areas affected by the Frye Fire.


Arizona religious leaders urge climate reform

12 dangerous creatures that call Arizona home

Group wants to ban hunting of bobcats, other big cats in Arizona

Feds release long-awaited recovery plan for endangered Mexican wolf

Read or Share this story: