Photo: Gerrit Vyn

Behind the Science

A Storm Gathers for North American Birds

Audubon’s new study reveals the devastation global warming will likely bring down on birds―and identifies the habitat strongholds they’ll need to hang on.

Western North Dakota is famous for its birds. The land here is checkered with neat squares of farm fields and native prairie overlying a scatter of pothole lakes, their curving shorelines shaped tens of thousands of years ago by chunks of melting glaciers. This rich landscape provides critical breeding grounds for millions of birds, from the Mallards and Blue-winged Teal that pour out of the so-called “duck factory” to the Bobolinks of the tallgrass prairie.

 

But the region is changing fast. Even as birds continue to flock here every summer, expanding agriculture has eaten away at their habitat, and since 2008 the area has witnessed an energy boom of global proportions. Today the fields, prairies, and badlands are punctuated with hundreds of rectangles of raw, orange dirt, each studded with its own set of trailers, storage tanks, and nodding pumpjacks. Every day, companies use hydraulic fracturing to extract nearly a million barrels of oil from the Bakken formation, a layer of shale that lies about two miles beneath the prairie. Roughly 8,000 wells are operating already, and an additional 40,000 could be drilled and fracked in the next 20 to 30 years. In line at one brand-new convenience store, a woman carrying a hardhat sums up the prevailing attitude: “Patience are for doctors.” In the Bakken, the time is now, and the future is a long way off.

 

Yet the Audubon Report, a groundbreaking new study by Audubon scientists, suggests that this place will become even more important for birds as the planet warms. For the 26 grassland bird species whose breeding ranges are projected to decrease dramatically by 2050, North Dakota will become an increasingly rare island of viable habitat and suitable climate conditions, one of their few remaining refuges. Protecting a portion of the region for birds could mean the difference between survival and extinction for some species.

 

That’s just one of the critical findings from Audubon’s seven-year investigation into the expected effects of climate change on North American bird populations. And taken together, the news is grim indeed. By 2080, the climate model projects, dozens of avian species across the country could be hurtling toward extinction—and not just birds that are already in trouble. Both the American Avocet and the Yellow-headed Blackbird, familiar sights in western North America, may be under threat before the end of the century. In the Great Plains, the Chestnut-collared Longspur’s range could shrink by 70 percent, while suitable breeding grounds for the Baird’s Sparrow could disappear entirely. The Piping Plover, an icon of the Atlantic Flyway, may vanish from many eastern shores.

 

Croplands have long been claiming North Dakota’s prairie potholes. The state’s current energy boom only adds to pressure on habitat. Photo Credit: Jim Brandenburg/Minden Pictures

 

The numbers are stark: Of the 588 species Audubon studied, 314 are likely to find themselves in dire straits by 2080. Unless, that is, the oil boomers in the Bakken—and everyone else—start to consider the future. Unless we begin to reduce the severity of global warming and buy birds more time to adapt to the changes coming their way.

 

Global climate is changing in ways not seen for millennia, and we know humans bear at least part of the responsibility. We also know that these changes are affecting animals large and small. For years scientists have been telling us that the ranges of bears, butterflies, and many other species are shifting north and toward the poles; that bird migrations are changing time and course; and that pollinators are trying to adjust to new flowering schedules. These alarming observations are only the beginning.

 

To make predictions about the effects of climate change on animals, scientists need years, if not decades, of solid, detailed data on where and when species have been in the past, and such data are very rare. Except when it comes to birds.

 

For more than a century, volunteer birdwatchers throughout the Americas have contributed observations to Audubon’s annual Christmas Bird Count. Begun as a way to assess the health of bird populations, data from the annual census are now key to predicting birds’ responses to climate change. Using hundreds of thousands of standardized observations from both the Christmas Bird Count and the North American Breeding Bird Survey, Audubon’s chief scientist, Gary Langham, and his colleagues were able to describe the “climate envelope” for each of 588 North American bird species—pinpointing the range of temperatures, amount of rainfall, and other climate characteristics of the habitats occupied by each species. Then they looked for each combination of characteristics within sophisticated computer projections of the global climate, finding the future climate envelopes—and, by extension, the potential future ranges—of the species and mapping them to a resolution of 10 square kilometers. The study projects, for instance, that the Baird’s Sparrow’s range will shrink more than 90 percent by 2050 to just a small area within the Bakken.

 

It’s the broadest and most detailed study of its kind for North America, and it’s the closest thing we have to a field guide to the future of these birds. “It’s really important new information,” says Stuart Butchart, head of science for BirdLife International, who wasn’t involved with the study. “It shows us which species we need to be most worried about, and it helps us understand the whole suite of new challenges that these species will be facing in the future.”

 

Those challenges are daunting. According to the Audubon analysis, which is currently undergoing peer review for journal publication, more than half of North America’s bird species will be “climate-threatened” or “climate-endangered” by the end of the century—under a range of future emissions scenarios. The 188 climate-threatened birds face losing more than half of their current range by 2080, although they have the potential to shift into new areas. The 126 climate-endangered species are projected to lose more than 50 percent of their current range by 2050, with no net gain from range expansion.

 

The study was done very conservatively, says Terry Root, a Stanford University biologist and Audubon board member who studies how wildlife responds to climate change. “The findings are showing us the best possible future, not the worst possible future,” she says. And even in that best of futures, where North America is two to four degrees Celsius warmer, 314 bird species could struggle to find places they can survive.

 

“That was just a punch in the gut,” says Langham. “When you realize that only nine bird species have gone extinct in continental North America in modern times, and then you see that we’re looking at 314 North American bird species at risk by the end of this century—it just takes your breath away.”

 

Some bird species will be able to adapt to new climatic conditions, but certainly not all. And while many people assume that climate change will simply shift habitats farther north or to higher elevations, for the 126 climate-endangered species, including the Baird’s Sparrow and other Bakken familiars, their climatic ranges are not only shifting but also dramatically shrinking. If we stay on our current carbon-spewing path, some of those species may have nowhere to go.

 

As a field guide to the future, the Audubon Report will help inform conservation investments, highlighting places that will continue to serve as valuable habitats in the decades to come. The study suggests that some important North American bird ranges will persist in place, acting as what Langham calls “species strongholds” as the climate changes. The prairies and pothole lakes of North Dakota are one such stronghold. Another is Appalachia.

 

The deciduous forests of West Virginia, North Carolina, and Virginia are home to several species of vulnerable warblers, notably the Cerulean Warbler. The tiny sky-blue bird, which nests high in treetops, is thought by some to be the fastest-declining songbird in North America; its winter habitat in the northern Andes has been dramatically reduced by coffee plantations, while its summer habitat in Appalachia is being steadily fragmented by, among other things, coal mining and low-density residential development. As the climate changes, the Audubon analysis shows, much of the Cerulean Warbler’s current range in the eastern United States is likely to become unsuitably wet and hot, and Appalachia’s forests will become an ever more important refuge for it and other warblers.

 

Audubon North Carolina has already begun to promote the protection of Appalachian land for warblers, working with state parks and private landowners to conserve the largest remaining swaths of intact habitat. The climate study, says Curtis Smalling, Audubon North Carolina’s director of land bird conservation, emphasizes the importance of that work. “If we can save the biggest blocks across a wide elevation range, then we will be able to slow these declines, and perhaps give these species a chance to adapt,” he says. “Identifying these strongholds makes the need for protection even clearer.”

 

For Smalling, the long-term perspective of the analysis is galvanizing. Like other conservationists on the ground, he’s most often dealing with emergency cases—species that are already critically endangered, for instance, or whose habitat is already doomed by development or climate change. The analysis not only highlights areas that will serve species for the long term but also points to now-common species that need preventive care. For instance, the study projects that the Ovenbird, a relatively common species that also breeds in Appalachian forests, will lose more than 90 percent of its climatic range in North Carolina by 2080.

 

“The hard thing, but also the nice thing, is that this study lengthens our time horizon,” says Smalling. “It thus forces us to say, ‘Hmm, what do we want this to look like 50 or 100 years from now?’”

 

Of course, the future is impossible to predict with certainty. To build the most accurate model possible, Langham’s team included only climatic variables and focused on birds within the United States and Canada. “If we included sea-level rise, prey base, species competition, all the complexities of ecology, it’d take decades, and birds might go extinct before we were done and even knew they were at risk,” says Langham. “What we have is a set of predictions that gives us a good idea of which species are most sensitive to the projected change in the near future. It allows us to make science-based management decisions, and adapt as we go.”

 

That said, Langham’s team is already working to incorporate additional data to generate even more robust projections. Next they will try to clarify how places the current model points to as climatically suitable for species in the future could fall short in other ways: They could be covered with asphalt, or be impossible for a species to reach because of distance or fragmentation. The habitat could be covered in trees—a possibly insurmountable challenge for a bird adapted to life among grasses. “If the right climate conditions for a species are in boreal forest, but the species has no idea how to make a living in boreal forest, that’s a problem,” says Langham. That’s why strongholds in places like the Bakken—areas that provide habitat for many species now and will continue to do so for many decades—are critically important to conserve, he says.

 

Audubon scientists would also like to expand the study’s scope to Mexico and south to Chile, into the wintering grounds of many migratory bird species. They haven’t been able to do that yet because the detailed, long-term observations so important to the Audubon model aren’t widely available for countries to the south. Cagan Sekercioglu, a University of Utah ecologist who studies the causes and consequences of bird extinctions around the world, says that while globally available digital apps like eBird are helping researchers collect more observations from more countries, the data gaps remain significant. “For these kinds of studies to be useful for actual conservation actions, they have to be done at a very high resolution, with very detailed data,” he says. As other countries in the Western Hemisphere start contributing information, the models could forecast which wintering grounds to the south are most vital to safeguard. 

 

Despite the model’s limitations, Langham says its predictions are crucial. “There are always asterisks, always caveats,” he says. “But we can choose to not do anything—which means being wrong for sure—or we can use this tool to figure out what the future holds and guide conservation efforts that give birds a chance to adapt.”

 

In and around the Bakken oil patch, the Audubon Report adds another level of detail to what many conservationists and land managers already knew: The region’s grasslands are important, endangered, and all too often ignored. Karen Smith, a Midwest native who managed the Lostwood National Wildlife Refuge from 1977 until her retirement in 2001, remembers her first visits to the Dakota prairie. “Why do I love it? It’s like trying to explain why you fall in love with someone,” she says. “It’s the wide-open space, the uniqueness, the unknowns. We’re still discovering new microorganisms in prairie soil. It’s unbelievable.”

 

When Smith arrived here nearly 40 years ago, much of the refuge’s grassland was being taken over by aspen and other woody species. She started grazing and controlled-burn programs, a combination that helped restore many acres of grassland and encouraged Upland Sandpipers and other prairie birds to return to the refuge to breed.

 

Young Common Loons, like this juvenile left high and dry when Wyoming’s Bergman Reservoir was drained for irrigation, will become an increasingly rare sight in the United States’ northern lakes as the climate warms and the species’ breeding grounds shift into Canada. Photo Credit: Michael Quinton/Minden Pictures/National Geographic Creative

 

Smith still lives near the northern edge of the refuge, in an energy-efficient straw-bale house she built with her family and friends, and her front windows face Lostwood. But just beyond the low hills that surround her home, pumpjacks dip over new wells on the edge of the oilfields. Federal budget cuts have made it difficult for current refuge staff to maintain her decades of restoration work, and bit by bit, oil wells, gravel pits, and the new and wider roads that accompany them are popping up around her.

 

Kory Richardson, the current manager of Lostwood, is working to protect both the refuge and the prairie habitat around it. In North Dakota the U.S. Fish and Wildlife Service manages nearly 300,000 acres of wildlife refuges and holds conservation easements on hundreds of thousands of acres of private wetlands. The easements are primarily designed to prevent wetlands from being converted into farmland, but they also help protect wetlands and prairies alike—the habitat strongholds that emerge from Audubon’s climate model—from some of the worst effects of the oil boom.

 

Richardson oversees both the Lostwood refuge and 176,000 acres of nearby wetland easements. When an oil company proposes sinking a well within an easement, Richardson and others negotiate with the company and the private landowner over the placement of well pads, roads, and pipelines. The easements preclude agriculture, not oil wells, so in most cases, the Fish and Wildlife Service doesn’t have any legal power to stop or even limit the oil development. But in many instances, the agency has convinced companies to avoid prairie potholes and other key habitats within the easements.

 

On the busy highways of western North Dakota, or on the frantic main streets of the region’s towns and cities, it’s easy to be daunted by the Bakken boom. There’s no question that it’s a pervasive, powerful force, and that Richardson and other managers have too little money, power, and time to protect wildlife from all of its impacts. But from the top of the latticed steel viewing tower in the middle of the Lostwood refuge, pothole lakes glint in the sunlight, and the region’s vast open spaces dwarf even the multiplying well pads. There’s still a lot of habitat worth saving.

 

Michelle Nijhuis reports on science and the environment. Her work appears in National Geographic and other publications. She lives in Washington State.