Arctic Blog: As Climate Warms,
By Steve Zack, Wildlife Conservation Society
A Shifting Landscape for Wildlife
2 Aug 2011
On the Dalton Highway south of Deadhorse, on Alaska’s North Slope, two of my colleagues from the Wilderness Society and I encountered a small herd of muskox. These beasts are the quintessential resident land mammal up here, and a true relic of the Pleistocene. They look like a shag carpet that has been tossed onto a Volkswagen bug, with horns replacing the front bumper. At this time of year, they are molting yards of wool, or qiviut, as their winter coat gives way to a cooler summer dress.
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The stiff wind that day was blowing large chunks of qiviut directly our way, the fur so thick and bunched in the air that we could grab it. The breeze, which I began to think of as the qiviut wind, brought us a memorable, warm day — a welcome relief from our weather this year in Arctic Alaska, which has been typically variable, and often raw. In the 10 days I was at Prudhoe Bay, and recently at our remote field site on the Ikpikpuk River, the weather has ranged from near freezing, with harsh winds off the frozen Beaufort Sea, to densely foggy with lighter winds, to 50 degree temperatures with clear skies and not a hint of a breeze. (The latter weather was perfect because it was in advance of the miserable mosquito season.)
Yet it is the increasing prevalence of such warm days that threaten this shaggy beast so exquisitely adapted to the cold. With its great and improbable fur, muskoxen will likely not be able to withstand the warming and the associated ecological changes that are sweeping across the Arctic. Temperatures here are warming at more than twice the rate as the rest the world, soaring 4 to 5 degrees F in recent decades. The receding summer Arctic sea ice has been well documented.
Yet there are changes on the Arctic landscape as profound and as worrisome. Permafrost — the perennially frozen soil just below the thin top soils — is warming and melting. Alaska’s Arctic shorelines are disintegrating and eroding, as stronger storms hammer a more exposed (because the ice has receded) and softened (because of the melting permafrost) coast. Such storms change the near-shore habitats to more salt-tolerant sedges. Land loss from such erosion and salt water inundation is more than a kilometer a year on average, a rate that has doubled in recent years.
But the main concern as the Arctic warms is that this region — a desert by annual precipitation measures — risks drying up in many areas. Evaporation is expected to exceed even the projected greater precipitation in the region’s rapidly changing climate. As the wet tundra is the most important wildlife habitat, drawing in millions of nesting migratory birds and calving caribou on the coastal plain, the risk of desiccation of shallow ponds and meadows is a tremendous concern.
Muskoxen are likely to face increasing difficulties as the Arctic rapidly warms.
The seasons are also changing, and changing dramatically. Winters are milder, springs come sooner, and falls linger longer. As I have seen with my own eyes, the seasons of flowering and of animal movements are being reshaped. Our studies of nesting birds, coupled with previous data from the 1980s, show a significant advance in nesting, with shorebirds and songbirds breeding more than 10 days earlier, on average, than three decades ago. In recent years, that trend seems to be accelerating. So far, the overall trend for nesting success and nest productivity seems unchanged.
That pattern of earlier nesting would seem to alter these birds’ complicated annual cycle of migratory movements and their need to solve energetically stressful activities around the calendar year. Arctic breeders arrive here after long journeys then gain energy for incubating eggs, raising their young, replacing body feathers, adding fat for migration, then flying south again. There, they replace more body feathers, build up fat reserves again, and begin migrating north — all in a calendar year with little room for temporal adjustment, as each phase involves a precise choreography timed with food availability. Shorebird migratory movements north and south also typically involve stopping over at wetlands when those wetlands are most productive.
Yet the earlier Arctic springs are altering that calendar, advancing the peak of insect abundance. As these birds hatch their young to coincide with such peaks, we believe that earlier nesting is an attempt to match hatching of their chicks with peak insect activity. For the past two years, we have added insect sampling in the tundra and in tundra ponds to understand when that peak is, and we hope, through time, to see if it, too, is advancing.
To test this idea, our field crews sweep our sampling ponds with a small net meant to capture aquatic stages of insects that will soon metamorphose into flying adults and potential prey of shorebirds. We also employ “pit fall” traps, where terrestrial insects stumble into long trays with a weak antifreeze that preserves such insects for subsequent sorting. This sampling is part of a larger, coordinated effort across many research sites in the North American Arctic as we try to assemble basic data on the impacts of warming in the region. Will these changes soon lead to a so-called “phenological mismatch,” where these migrants can no longer arrive in the Arctic in time for the earlier spring flush of insects?
And how will migratory birds deal with the “double whammy” of climate change? They are facing the warming Arctic in the north, yet many species are also facing predicted rising seas flooding their wetlands in the south. Rather than escaping the effects of the changing climate with their ample capacity as world travelers, they are being affected by different climate effects in their different ports of call, thousands of miles apart.
A WCS field assistant collects insects in an Arctic tundra pond.
The Arctic is also changing with an invasion from the south. The low, flat world of tundra is getting woodier, and there are clear signs of shrubs and small trees creeping northward. Spotting a large forest of tall alders well north of the Brooks Range last year on our Utukok River raft trip was telling. This forest was filled with American robins, a species more typical of lower latitudes.
Boreal animals from the south are becoming more common in the Arctic, and, in effect, moving northward with the vegetation and climate changes. Numerous waterfowl species, like greater scaup and American wigeon, have been arriving here outside their supposed breeding range. The red fox is encountering and supplanting the Arctic fox, as is now happening in Prudhoe Bay. A few years ago, we encountered Arctic fox regularly and red fox rarely. Now our encounter pattern has reversed. In my several field days at Prudhoe Bay this year, I saw several red fox, but no Arctic fox. We have monitored nests with cameras in order to understand which species are the most prevalent nest predators and this year we have detected red fox preying on shorebird nests for the first time. (We also recorded a few Arctic fox predations of nests this year; they are down but not out.) We have also seen moose here in the oilfields, hundreds of miles north of where they are more typically encountered. Are grizzly bears more common in the Arctic? Not sure. But anecdotes suggest they are, and that they are preying on muskoxen in the Arctic National Wildlife Refuge.
Flying south on a clear, warm day, I looked out the windows of the chartered jet carrying oil field workers and me. The Brooks Range lay below us, its glaciers retreating in the warming climate. No single field observation, whether earlier nesting or disappearing glaciers, confirms evidence of a changing Arctic. But taken together — the receding sea ice, the eroding shorelines, the earlier springs, the southern plants and animals creeping north — all point to a vitally important part of the world undergoing a profound transformation.
12 July 2011: Unraveling the Mysteries of Migration
19 July 2011: Tracking the Impact of Oil Development on Wildlife
26 July 2011: A Place for Wildlife in the National Petroleum Reserve