One hundred years after America drove the passenger pigeon extinct, the country is on the cusp of an even bigger bird debacle. Instead of losing one species to overzealous hunters, though, we could lose hundreds of species within decades to a much broader man-made disaster: climate change.

This threat is outlined in two major reports issued this week. One, released Monday by the National Audubon Society, uses seven years of research to examine the effects of climate change on 588 bird species. The other, "State of the Birds 2014," is a wider overview of America's avian health released Tuesday by a 23-member coalition of federal agencies, universities and conservation groups.

Both reach similar conclusions: Man-made pressures, namely climate change and habitat loss, are outpacing many birds' ability to adapt, forcing them to find new homes or fade away.

Hundreds of American birds are at "serious risk" due to climate change, according to the Audubon report, including some already-weak species as well as others that are stable for now. (As the passenger pigeon proved, a species can go from billions to none surprisingly quickly.) Of the 588 bird species Audubon studied, more than half will be "climate-threatened" or "climate-endangered" by century's end. Even in the most optimistic scenarios, the report warns 314 species will struggle to survive in 2100.

"That was just a punch in the gut," Audubon chief scientist Gary Langham says in a news release about the report. "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."

bald eagle

Bald eagles are projected to have only 26 percent of their current breeding range left by 2080. (Photo: Carl Chapman/Flickr)

Flying the coop

No U.S. bird is more iconic than the bald eagle, already a conservation success story due to its comeback from pollution and pesticide poisoning last century. But the national bird's habitat could decrease by 75 percent in 70 years, according to Audubon, as climate change jumbles ecosystems.

And bald eagles are hardly the only high-profile birds at risk: Several state birds may vanish from the states they represent, including the mountain bluebird (Idaho and Nevada), brown pelican (Louisiana), Baltimore oriole (Maryland), common loon (Minnesota) and ruffed grouse (Pennsylvania). Some of these and other climate-stressed species will likely follow their native climates to new locations, researchers say, but that may just be a short-term solution. And many species won't even have that option.

The 188 climate-threatened birds could lose more than half their current range by 2080, although Audubon scientists predict some of those will simply move to new areas. The 126 climate-endangered species, however, are expected to lose more than half their current range by 2050 — a full three decades earlier — and they will see "no net gain from range expansion."

That's because habitats aren't just moving; they're also shrinking, fragmenting and fading away, due to climate change as well as other human activities like construction and energy extraction. This broader issue is a key focus in State of the Birds 2014, which groups American birds by habitat type. It finds the most severe declines among migratory shorebirds, followed by species in aridlands (desert, sagebrush and chapparal habitats), grasslands, Eastern forests and Western forests:

"Because the 'state of the birds' mirrors the state of their habitats, our national wildlife refuges, national parks, national seashores and other public lands are critical safe havens for many of these species — especially in the face of climate change, one of the biggest challenges to habitat conservation for all species in the 21st century," U.S. Interior Secretary Sally Jewell says in a statement.

On top of big habitat shifts, birds are also hurt by smaller-scale threats like invasive species and pollution, the report notes. Non-native cats, rats and mongooses are killing rare songbirds in Hawaii, for example, a state already deemed the "endangered species capital of the world." Many ocean birds are also suffering from the spread of plastic debris, which they mistake for food and bring to their chicks. Combined with climate change and ocean acidification, this is too much for many birds to bear.

Wing and a prayer

Some degree of climate change is already inevitable, since heat-trapping carbon dioxide emissions can linger in the sky for centuries. But that doesn't mean it's too late to prevent bird die-offs. Both of this week's reports point out an important ray of hope for birds across North America: We've already proven that conservation can save some bird species from extinction. It's working for bald eagles, brown pelicans and whooping cranes, and there's reason to believe it can work again.

The charts above, for instance, show two kinds of birds on the rise: those in wetlands and those wintering on coasts. This is largely due to federal conservation efforts, including the creation of national wildlife refuges and national seashores as well as laws like the 1972 Clean Water Act and the 1989 North American Wetlands Conservation Act. These habitats aren't problem-free, of course — more than 17 million acres of U.S. wetlands have been lost since the 1950s, while coastal birds face threats like oil spills, beach development and sea-level rise. Yet they've grown despite such hurdles, suggesting habitat preservation can go a long way in helping embattled birds dig in their heels.

Chincoteague NWR

Protected habitats like Chincoteague National Wildlife Refuge in Virginia are vital havens for birds. (Photo: Steve Hillebrand/USFWS)

Some habitats are hardier than others, though, thanks to a mix of topography, geology and elevation that can buffer wildlife against high-speed climate change. Preserving these "climate strongholds" will be critical in coming decades, according to the Audubon report, especially in parts of the recently identified Appalachian climate refuge. Areas like these aren't immune to climate change, but by resisting the fast pace of man-made warming, they could give some birds more time to adapt.

"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," says Curtis Smalling of Audubon North Carolina. "Identifying these strongholds makes the need for protection even clearer."

Although habitat loss played a role in the passenger pigeon's decline, the driving force in its extinction were relentless hunters who chased flocks around the country. That may not be an issue for endangered birds of today, but researchers say there's still a lesson to be learned: Even the most abundant species can disappear quickly if we take them for granted. Tackling the causes of climate change and habitat loss won't be easy, but it will only grow more difficult with time.

"The best way to save an endangered species," says University of Georgia wildlife ecologist Bob Cooper in a statement released this week, "is to do so before it becomes endangered."

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