Feeling the Heat

Feeling the HeatClimate change is altering Montana’s wildlife and
fish populations, habitats, and recreation.
By Tom Dickson

This story is featured in Montana Outdoors
March–April 2009

One of the great joys of midsummer trout fishing in Montana is standing waist-deep in a cool river as a refreshing breeze wafts off the water. Unfortunately, such pleasures are disappearing as the state’s famous blue-ribbon rivers simmer under some of the hottest summers on record.

Trout anglers thought things were bad enough in 2001 and 2006, when thermometers registered unprecedented summer highs across much of Montana. But 2007 was worse. In July both Helena and Billings recorded eight days above 100 degrees. On July 6, when Missoula’s afternoon temperature usually tops out at about 83, the city set a record of 107, the first of an unprecedented 11 days above 100.

The same blistering heat was baking nearby trout rivers. Yellowstone National Park’s Firehole River, just a few miles from the Montana border, was closed after it hit 82 degrees, killing hundreds of trout. The Big Hole River upstream from Wisdom reached nearly 80 degrees and dwindled to a trickle of just 13 cubic feet per second. Water temperatures on the Yellowstone, Blackfoot, Beaverhead, Big Hole, and other blue-ribbon rivers topped 73 degrees for three consecutive days, triggering manda­tory stream closures to protect trout from the added stress of being caught and released. By summer’s end, Montana Fish, Wildlife & Parks had been forced to close or tightly restrict fishing on a record 29 rivers. As the heat wave drove thousands of disappointed anglers indoors, it scorched the fishing industry’s bottom line. “August that year was just dead for us on the Missouri,” says Chris Strainer, owner of the Cross Currents fly shops in Helena and Craig. “I’d look out the window on a Saturday afternoon and not see a single boat on the water.”

Hotter, longer summers and shorter, warmer winters have become the norm in Montana over the past decade. The cause, say climate scientists, is a changing global climate. As temperatures continue to increase, Montanans will see even greater alterations in precipitation, drought duration, snowpack levels and runoff, and the timing of plant and animal cycles. Already the warming has delayed waterfowl migrations, shortened ice-fishing seasons, and made elk hunting tougher by allowing the animals to stay high in the timber throughout the season. “Hunters and anglers are often the first people in Montana to witness the effects of climate change,” says Bill Geer, Climate Change Initiative manager with the Theodore Roosevelt Conservation Partnership. “Climate change isn’t some abstract theory to a trout angler who can’t fish the Beaverhead because it’s closed, or an elk hunter who waits all fall for elk that never come down. It’s a reality we’ve been dealing with for years.”

And there’s no relief in sight. In the not-too-distant future, Montanans could see smallmouth bass replacing trout in some rivers, fewer mountain goats and other alpine species, earlier and more widespread summer stream closures, and millions more acres of dead and dying beetle-infested forests (see sidebar, below). Concerned about these and other warming-caused scenarios, FWP officials have begun studying how a changing climate might help or hurt fish and wildlife and figuring out ways to revise management activities in response. “We certainly can’t stop climate change,” says Ken McDonald, FWP Wildlife Division chief, “but we know it’s coming, and we have a responsibility to prepare for the impacts on Montana’s wildlife.”

Hot sky country
People may argue over how much of climate change is manmade, but there’s no disputing that the planet is warming. The latest report from the Intergovernmental Panel on Climate Change (IPCC) says temperatures have increased an average of 1.5 degrees F worldwide over the past century and are expected to climb another 4 to 12 degrees, depending on carbon dioxide levels, by 2100. According to Dr. Steven Running, an ecology professor and climate expert at the University of Montana, the average annual temperature in Montana has increased 2 degrees over the past 50 years, even more than the global average. “There’s no doubt in my mind that global warming is real and that the impacts to Montana will accelerate,” says Running, a lead author of the IPCC’s most recent report.
Climate has been in flux throughout history, Running says, but temperatures since the late 1800s, and especially during the past three decades, are higher than at any time in at least the past 13,000 years. The warming is the result of what’s known as the greenhouse effect, caused when carbon dioxide—produced by the burning of oil, coal, or gas—traps heat within the earth’s atmosphere. Even with new efforts to cut down on emissions, Running says, global oceans during the past 50 years have absorbed so much additional heat—which will be released later—that continued warming is inevitable. He and other climate experts predict that Montana’s average temperatures will rise another 3 degrees by 2050.

One of the most noticeable and significant effects will be a thinner and faster-melting mountain snowpack. Snowpack keeps valley rivers cool and flowing as it slowly melts in summer. Though total snowfall in western Montana will likely remain the same, says Running, “warmer late-winter temperatures will mean the snowpack won’t stay on the mountains and politely melt in June and July when we need it.” That’s trouble for trout. Without adequate snowpack, river water can warm to the point where the fish die of heat stress or levels drop so low they become stranded. Monitoring stations in Billings and Kalispell show that average March air temperatures are up 6.2 degrees and 7.8 degrees, respectively, from what they were 50 years ago. April 1 snowpack in western Montana has declined 30 to 40 percent and peak river runoff arrives on average ten days earlier. “In a few decades, Montana’s climate could look a lot more like what Utah now has,” Running says.

Bad for bull trout and grayling
“Global warming is the single greatest threat to the survival of trout in America’s interior West,” concludes a recent report jointly published by the Natural Resources Defense Council and Montana Trout Unlimited. To make matters worse, the trout and other salmonids most vulnerable to warming are already in trouble. Numbers of arctic grayling in the Big Hole River dropped from an average of 60 per mile in the 1990s to roughly 10 in 2006. And rising temperatures could drastically shrink the range of bull trout, which need extremely cold water for spawning and rearing, says Dr. Bruce Rieman, research scientist emeritus with the U.S. Forest Service’s Rocky Mountain Research Station in Missoula. Other possible losses in Montana include shrinking wetlands, smaller cutthroat populations, withering sagebrush ecosystems, and fewer high-elevation birds (see sidebar, below). Montana also stands to lose most of its whitebark pines, which produce seeds eaten by grizzly bears, Clark’s nutcrackers, and other wildlife. A critical subalpine ecosystem species, whitebark pines are being “devastated” by heat-loving mountain pine beetles, says Diane Six, a University of Montana professor of entomology.

A warmer, drier Montana would not threaten all wildlife. Adaptable species such as Canada geese and white-tailed deer would likely thrive. Woodpeckers, bluebirds, and other cavity-nesting birds would benefit from the snags created by beetle infestations and wildfires. There would be fewer March blizzards, which often kill winter-weakened elk, mule deer, and pronghorn. And wild turkeys and other species restricted by Montana’s frigid temperatures would prosper from milder winters. Some fish species also would thrive as Montana streams and rivers warm up. Brown trout already are appearing farther upstream on the Yellowstone River than ever before. Less turbidity from fewer summer thunderstorms has benefited the non-native smallmouth bass, a sight-feeding fish spreading west in the Yellowstone from Miles City to Billings.

“We know that changes in fish populations will continue to occur, but no one really knows what the tipping point is for natural aquatic systems and how well they can adapt to change,” says Chris Hunter, chief of the FWP Fisheries Division.

Habitat-based response
FWP officials say the best re­sponse to climate change is to redouble efforts to protect and restore vital habitat. “What’s essential is to maintain water in streams, no matter how warm it gets,” says Hunter. One successful example has been to obtain water from landowners through leases, donations, and cooperative agreements that maintain the minimum river flows fish need to survive. “We also have to restore and protect more streamside vegetation that shades and cools water,” Hunter says. FWP fisheries biologists aim to replicate successful landscape-scale conservation work already underway in several watersheds. On the Blackfoot River, for example, landowners, trout anglers, and other conservationists have restored 80 miles of river and tributaries and protected 95,000 acres of private land with perpetual conservation easements. On the Big Hole, state and federal agencies have worked out an agreement with ranchers, who agree not to draw water from the river and its tributaries for irrigation when late-summer flows decline to dangerously low levels. Other projects that help Montana trout survive: reconnecting stream stretches blocked by culverts and dams, reducing siltation from old logging roads, and building watering tanks so cattle can be fenced away from stream banks.

Wildlife officials advocate a similar multi­pronged, habitat-based approach. “Our goal is to protect and restore ecosystems to make them more resilient to the effects of climate change,” says McDonald. Identifying critical habitats and protecting them by purchasing conservation easements and wildlife management areas will be key. Especially important will be riparian habitats—what McDonald calls “ecological arteries for the entire landscape”—such as the Marias and Yellowstone wildlife management areas acquired in 2008. Conservation agencies and organizations will also need to maintain connections between critical habitats so wildlife such as wolverines and lynx can move across the landscape as they seek cooler temperatures.

Those efforts may still fall short for particularly vulnerable species. At a recent climate change workshop sponsored by FWP, the National Wildlife Federation, and other conservation organizations, Dr. Molly Cross of the Bozeman-based Wildlife Conservation Society predicted that “species unable to adapt or migrate will be in big trouble.” She said that if adjusting management activities does not work, conservation agencies and organizations may need to consider triage. “The idea would be to focus attention on species with the best chances of survival and, hard as it might be, reconsider the efforts we spend on species we probably can’t save because the warming will make it useless to try.”

To learn which species will likely fare best and worst under warmer Montana skies will require more research and population monitoring. The Association for Fish and Wildlife Agencies recommends that Montana and other states boost efforts to identify and assess likely effects of future warming on populations and habitats.

Where would new money for accelerated habitat conservation and research come from? According to Tom France, director of the National Wildlife Federation’s Northern Rockies office at Missoula, one option is to use revenue generated by the so-called cap-and-trade system, proposed to encourage industries to reduce carbon dioxide emissions. Under a provision of the Climate Security Act added by Montana’s Senator Max Baucus, states would share in roughly $9 billion of additional funding. Though the proposal had widespread bipartisan congressional support last year, “with the current economic climate, it’s hard to predict if the fish and wildlife component will survive,” France says.

New funding sources will be essential if Montana wants its fish and wildlife management programs to adapt to changing climate conditions. No matter how budget scenarios play out, however, FWP officials say they will continue to focus on making the state’s most important land and water habitats as resilient as possible. “Montana’s fish and wildlife are also feeling im­pacts from many other sources, such as invasive species and growing transportation and en­ergy development,” says McDonald. “Our focus continues to be to protect and restore critical habitats so that landscapes and wildlife can, to the extent possible, withstand climate change—or whatever other stresses they face in the future.”Bear bullet

Tom Dickson is editor of Montana Outdoors.

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From Evergreen to Everrust

In recent years, western Montana forests have been hit by a massive infestation of mountain pine and Douglas fir beetles, transforming them from a sea of green into a sea of rust red. More than 1 million acres of forestland across western Montana have been killed by tiny beetles that have thrived in the state’s warming climate. Millions more acres are at risk, according to the U.S. Forest Service.

One of the hardest-hit areas is the 1-million-acre Helena National Forest. Amanda Milburn, the forest’s silviculturist, says infestations have exploded from 19,000 acres in 2004 to 350,000 in 2008, an 18-fold increase. In portions of the Bitterroot National Forest, nearly every conifer has been killed by beetles. And vast tracts of the Beaverhead-Deerlodge National Forest have turned gray as needles fall to the forest floor, leaving only bare trunks and branches. 

Pine bark beetleThe native insects, of the genus Dendroctonus (Latin for “tree killers”), bore through a tree’s outer bark and lay their eggs. The larvae eat the sweet layer of inner bark a tree needs to transport water and nutrients from the soil to the branches. Healthy trees fight back by producing a resin that drowns the insects. But old and drought-weakened trees cannot produce enough resin to fight off the invaders.

Forest ecologists say the beetle epidemic has several causes. Decades of fire suppression has produced forests of similarly aged lodgepole pine. Many trees are now a century old, near the end of their natural life­span. Recent intense heat and drought further weaken trees. And mild winters allow beetles to thrive during colder months when large numbers historically have died.

Beetle infestations are natural to forests. Dying trees provide habitat for woodpeckers, bluebirds, and other tree-cavity dwellers before falling to the forest floor and decomposing into soil. But recent infestations—when added to dryer summer temperatures—have greatly increased the risk of intense wildfires. Another concern: The beetles are spreading to higher elevations. Scientists are particularly worried about the loss of whitebark pine. The thick-trunked trees produce cones heavy with high-caloric seeds that grizzly bears need to build fat in late summer. Dr. Diane Six, a professor of entomology at the University of Montana, says scientists previously thought whitebark pines grew at elevations too high and chilly for beetle infestations. “We’re now seeing 700-year-old whitebarks being killed off by this epidemic. It’s tragic,” she says.

Though the beetle infestation is too vast to be treated with insecticide spraying, thinning stands can help reduce the beetle’s spread. The dead trees can be salvaged for lumber, though the boards have a blue stain from a fungus the insects inject into trees. According to Milburn, the beetles eventually will run out of live trees and die from lack of food. “Other than that, the only thing that will knock them back is several weeks of extremely cold temperatures in midwinter or sustained late-spring frosts,” she says.

 

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Possible fish and wildlife losses as climate change continues:

Fewer ducks and other wetland species
Federal waterfowl managers say warming temperatures could dry up wetlands in North America’s Prairie Pothole Region (including portions of northeastern Mon­tana), halving waterfowl populations by the end of this century. “Several large public wetlands in central Montana have been dry for going on nine years now,” says Jim Hansen, FWP wet­land wildlife coordinator. “The lack of winter runoff and heavy spring rains might be reducing duck production in that region, not to mention waterfowl hunting opportunities.”

Fewer Yellowstone cutthroat trout
“The Yellowstone cutthroat trout would eventually be restricted to the cooler headwater streams,” says Chris Hunter, chief of the FWP Fisheries Division. “We won’t find them in the big rivers like the Yellowstone anymore.”

Depressed sauger populations
“Sauger need the turbid water that comes from runoff, and we expect to see less of that in the future,” says Matt Jaeger, FWP Yellowstone River fisheries biologist at Glendive.

Increased wildfire
The combination of unlogged century-old stands, earlier snow­­melt, longer and drier summers, and increased beetle infestations (see sidebar, page 20) would increase the intensity and duration of Montana wildfires. The U.S. Forest Service predicts that if average summer temperatures warm by just 1.6 de­grees over the next century, wildfire acreage in Montana would at least double. Periodic wildfires are essential for recycling nutrients in forest ecosystems. But intensely hot fires can sterilize soil and cause silt and ash to wash into trout streams during subsequent rains.

Shrinking sagebrush-steppe ecosystems
The U.S. Forest Service estimates that each 1.8-degree temperature increase would cause the loss of 12 percent of the West’s current sagebrush habitat, essential for sage-grouse and important for mule deer, pronghorn, and other wildlife. Plant ecologists say a major reason for the loss is that cheatgrass—an invasive species that thrives in hot, open, fire-prone environments—will crowd out native sagebrush.

Fewer moose
Moose need cool, wet habitat. Though Montana’s population appears stable so far, another northern moose state, Minnesota, has seen its population decline by 35 percent since the 1980s. The main cause ap­pears to be heat stress from warmer winters and springs.

Fewer breeding birds
In addition to shorebirds and wetland species, warming would put the white-tailed ptarmigan, gray jay, and other high-elevation birds at risk. “We’re particularly concerned about the black swift, which is an uncommon species that nests behind glacier-fed waterfalls,” says Amy Cilim­burg, director of bird conservation for Montana Audubon.

Declining wolverine populations and range
Because wolverines need deep mountain snow for denning, warming temperatures could reduce the species’ range in Montana. “In the Saw­tooths, for example, every den is above 5,000 feet,” says Dr. Kevin McKelvey, of the Rocky Moun­tain Research Station in Missoula. “A mother will actually move her litter uphill if the snow begins to melt, even if the young aren’t ready to emerge.”

Delayed bear hibernation
Warmer fall temperatures are delaying grizzly bear hibernation. Many bears now stay out during the big game season, increasing incidents of hunters surprising grizzlies feeding on downed elk and deer. “Delayed denning has become a factor we now have to consider when addressing conflicts between humans and grizzlies,” says Ken McDonald, chief of the FWP Wildlife Division.

Other potential problems

 

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