Climate change: The struggle for survival

Climate change becomes a rapid, unplanned survival experiment for animal species

Elizabeth Harball, E&E reporter

EENews.

10 February, 2014

It's hard to hunt seals when there is no ice. Photo by Mark Travers

In the 1993 blockbuster movie "Jurassic Park," a sleazy scientist played by Jeff Goldblum quips that "life finds a way." For real biologists, climate change is like a massive, unplanned experiment, one that may be too fast and strange for some species to survive it.

Some animals are already in the middle of it. As Arctic ice shelves melt, polar bears are ransacking seabird nests to sustain themselves. Migrating geese are exploring valuable but previously unseen real estate, due to melting permafrost.

But whether these adaptation attempts will succeed remains a big question, researchers say. As temperatures rise, entirely new environments are forming, changing how species interact with each other and their surroundings in often unexpected ways.

"We're likely to see different habitats form than what we see now," said T. Douglas Beard Jr., who heads the U.S. Geological Survey's National Climate Change and Wildlife Science Center. "What we don't understand is how these new communities will be assembled. So if you get a whole new type of flora, a whole new type of forest that no one's ever seen before ... it's pretty unknown which species are going to be able to flourish and those that will struggle."

Polar bears turn from seals to eggs

One of the most swiftly shifting environmental regimes is the polar north, where habitats are heating up faster than other parts of the Earth. The changing behavior of a top predator, the polar bear, is having a big impact on other species..

As sea ice slowly, steadily declines in the Canadian Arctic, polar bears are less able to walk out onto the frozen ocean and prey on seals, their favorite winter food source.

"For most bears, over 95 percent of their energetic needs are met by ringed seals and bearded seals," polar bear expert Andrew Derocher, of the University of Alberta's Department of Biological Sciences, said in an email. According to Derocher, hundreds of bears that once spent most of their lives on ice are now confined to land during the summer, forcing them to seek out new food sources.

A study published this week found bears have increasingly turned to bird eggs in a last-ditch effort to fatten up. Since the 1980s, researchers concluded, bear raids on colonies of two different bird species in northern Quebec have increased sevenfold.

Unlike foxes, the birds' usual predators in the region, polar bears swim to islands that host large colonies of nesting birds and proceed to tromp through and eat massive quantities of eggs, said Sam Iverson, lead author of the study and a Ph.D. candidate at Carleton University in Ottawa, Ontario.

"When bears came on, we generally saw a total reproductive failure on colonies," Iverson said. "With less ice, more frequent visits by bears is an increasing problem."

Iverson doubts this shift in bear diets will threaten the species he studied with extinction -- other colonies exist in Maine and Europe -- but he does expect significant local population declines. However, species with more limited habitat, like some seabirds, may not be so lucky, he said.

Even unluckier are the polar bears, as bird eggs are unlikely to make up for the species's inability to access seals.

"Our energetics modeling suggest that birds cannot make a meaningful contribution to a polar bear population," Derocher said. "To the individual bear, the energy return might be meaningful, but you can't feed [more than] 2,000 bears on bird eggs."

Geese have a new home, but for how long?

But there are some winners as the climate shifts -- at least for now. In the northern regions of Alaska, a habitat newly created by climate change is driving a game of musical chairs among visiting geese.

A female polar bear with two cubs raids an island colony of common eider ducks in Nunavut. Photo by Steve Marson.

What is likely a combination of rising temperatures, more powerful storm surges, sea-level rise and land subsidence has transformed portions of Alaska's Arctic Coastal Plain. Thawing permafrost near the ocean shore has given way to expanses of short-leafed, salt-tolerant plant species. They are forming salt marshes that more closely resemble a golf green than the Arctic tundra -- habitat that happens to be perfect for black brant geeseBlack brant geese migrate into this region in mid-July to molt, a period when they are unable to fly for about three weeks. In the 1970s, most of these geese -- close to 70 percent -- would settle down by Teshekpuk Lake, near Barrow, Alaska, where there was plentiful forage and a place to swim to safety. Then, only about 30 percent of the geese spent this time near the coast.

But today, the numbers have switched: About 70 percent of the black brants now molt along the coast, having discovered the recent expansion of a new rich food source along the Beaufort Sea.

"There's no evidence that the birds are having difficulty on those inland lakes, it's just that the coast is probably even better," said Paul Flint, a research wildlife biologist with the USGS based in Anchorage, Alaska, who has authored three studies on the geese. "You get on the ground out there and you realize, holy cow, there is a lot of good forage."

But sea-level rise and storm surges, the very forces that are helping drive the establishment of this new habitat, could destroy it in the coming years, Flint said.

"It's a bit of an arms race," Flint said. "We don't have enough data, we don't have enough time series to know which process is going to win out -- are [fertile salt marshes] going to keep advancing inland, or will coastal erosion take over and wipe it all out?"

How much hope for moss-eating pikas?

Because climate change is spurring such quick yet complex shifts, it vital for researchers to understand the hows and whys of animals' reaction to climate change, said USGS ecologist Erik Beever.

"Climate is a spatially and temporally complex phenomenon," Beever said. "It's really incumbent upon scientists to try to understand the mechanisms by which climate is acting upon species and communities and ecosystems, because if we don't understand how and why species are being affected, we don't know what to try to do with climate [adaptation] management or conservation."

A common eider guarding her nest, a more dangerous proposition than it used to be. Photo by Sam Iverson.

For this reason, Beever has been studying the habitats and behavior of the American pika for more than two decades. Today, uncertainty surrounds the fate of these small mammals that depend on cool, high-elevation habitats in the mountainous western U.S. In 2003, a study found that six out of 25 pika populations historically located in the Great Basin had disappeared. Between 2003 and 2008, Beever, the lead author of the earlier study, returned to find that an additional four populations had died out.

But scientists recently discovered that one pika population in Oregon and Washington's Columbia River Gorge is surviving in hotter weather and lower altitudes than its counterparts. They think the pikas are coping by eating moss, which grows year-round and doesn't require the pikas to leave the cool, safe comfort of rock slides.

The researchers were surprised because moss is far from an ideal food source: "Very few mammals are able to eat moss," said Johanna Varner, a biologist at the University of Utah and lead author of the study. "It's basically the nutritional equivalent of eating a cereal box."

Varner and her colleagues discovered that the pikas have been eating the moss twice to compensate -- first fresh, then again as feces. To be clear, climate change is not driving pikas to eat more of their own poop -- it's common behavior, Varner said, and this population may have been doing this since before the era of fossil fuels.

But how much hope does this apparent flexibility give us for the future of pikas? As with black brant geese and polar bears, perhaps not enough.

"What I think we can safely say from my study is that they seem quite adaptable in terms of what they're able to eat," Varner said. "The jury is still out whether or not this means anything for pika populations that are dying off."

At best, scientists can say that the way species react to climate change will be nuanced, but learning how to manage unpredictable animal shifts in the face of climate change is a tall order. For millions of years, species have been subjected to weather extremes and shifts in climate, but the rapid onset of global warming today is a novelty -- and, likely, a huge challenge. One recent study predicted that about a third of animals could lose more than half their present range by the 2080s (ClimateWire, May 13, 2013).

"There's no doubt there's going to be winners and losers," said Beard of the USGS. "Sitting here trying to divine the winners and losers is not the easiest thing."