by Mark Petrie, Ph.D., and Fritz Reid, Ph.D.
Many of us in the lower 48 will never hunt in Alaska. Separated by a four-figure airline ticket and some intimidating geography, the state can feel a little out of reach. But Alaska is generous with its birds. Nearly 20 percent of all waterfowl get their start here, and all four flyways get a share of these ducks and geese.
The "Alaska Territory" was actually purchased from the Russians in 1867. It was something of a fire sale. For $7.2 million the U.S. government received 365 million acres of land at about two cents an acre. Apparently the tsar thought he had all the tundra and forest he needed.
Alaska is big. Texas and California would fit in its borders with room for New England to stretch its legs. But perhaps the state's most impressive resource is water. Alaska has nearly 175 million acres of wetlands, more than all other states combined.
As Alaska celebrates 50 years of statehood, we salute its contribution to North America's waterfowl populations. Unfortunately, many states and provinces continue to lose habitat. As these losses mount, Alaska's role in maintaining healthy populations of ducks and geese has grown. Let's examine this role and look at some remarkable changes in breeding duck numbers in the state. To do that, we'll start with a brief description of Alaska's waterfowl habitat—no small task in a state of nearly 600,000 square miles.
For the sake of this discussion, let's divide Alaska into four areas: the Arctic coastal plain, the west coast, the interior, and the south coast. The Arctic coastal plain lies north of the Brooks Mountains and stretches to the coasts of the Beaufort and Chukchi seas. The Arctic coastal plain totals about 45,000 square miles and consists of poorly drained tundra with continuous permafrost. In spring, snow and ice on top of this permafrost melts and collects in shallow "thaw lakes." The density of wetlands here is staggering. Between Barrow and Prudhoe Bay, 85 percent of some areas is covered with water. Teshekpuk Lake lies in the middle of this coastal plain and provides some of North America's most important habitat for molting geese. Here too is America's National Petroleum Reserve and the Arctic National Wildlife Refuge (ANWR). As oil prices have soared, the debate over drilling in ANWR and the coastal plain became front page news.
Alaska's west coast extends from Kotzebue Sound and the Seward Peninsula to the Bristol Bay Lowlands and includes the Alaska Peninsula and Aleutian Islands. This area has 87,000 square miles of waterfowl habitat, most of which is subarctic tundra bordering the Bering Sea. Much of this region's habitat consists of large river deltas, near-shore lagoons, and tidal flats. Nearly half of all waterfowl habitat in western Alaska occurs in the famed Yukon-Kuskokwim Delta (Y-K Delta), the largest river delta in western North America. Most of the Y-K Delta is part of a 19.5-million-acre national wildlife refuge, an area larger than Maine and one of the most important waterfowl habitat areas on the continent. Alaska's west coast also includes Izembek Lagoon with its 85,000 acres of eelgrass beds—the largest in the world—which provide vital food for staging Pacific brant.
Interior Alaska is framed by the Brooks Range in the north and an irregular boundary of the Kuskokwim, Alaska, Wrangell, and Chugach mountains in the south. The region boasts 88,000 square miles of high-quality waterfowl habitat. Boreal forest, not tundra, dominates this part of the state. Although Alaska's interior is mountainous, it contains several major river systems, including the Yukon, Koyukuk, Innoko, Kuskokwim, and Tanana. Most waterfowl in the interior occur along these mighty rivers, where seasonal flooding and long daylight hours combine to provide a burst of summer productivity. The largest and best known of these floodplain wetland systems is the Yukon Flats.
Alaska's south coast stretches in a 1,000-mile arc from Cook Inlet to Ketchikan and is bordered by high mountains in the north and the Gulf of Alaska in the south. Eighty percent of Alaska's people live in this coastal arc. Most of this area is comprised of northern rainforest, and its winters are mild. The south coast's most important waterfowl habitat includes the coastal marshes of the Cook Inlet and several large river deltas, most notably the Copper and Stikine river deltas.
Alaska is part of the traditional survey area (TSA), which also includes the prairies, Canada's western boreal forest, and the Northwest Territories. The survey provides breeding population estimates for North America's most commonly harvested ducks and is the world's longest-running wildlife inventory. Although parts of Alaska's west coast, interior, and south coast are included in the survey, the Arctic coastal plain is not.
In the late 1950s, the total number of ducks in the TSA averaged about 38 million birds a year. During that time, Alaska had about 1.85 million birds or about 5 percent of surveyed ducks. As such, Alaska's contribution to continental duck populations appeared to be minor. Fast forward 50 years. Between 1998 and 2008, the number of ducks in the TSA averaged about 37 million birds, almost identical to the 1950s. What had changed was Alaska's contribution. During the past decade, Alaska has supported an average of 5.4 million breeding ducks. Not only has Alaska's breeding population seemingly tripled since the 1950s, but the state now accounts for 15 percent of all the ducks in the TSA.
Breeding duck increases since the 1950s have been largest in Alaska's west coast and interior regions. Although duck numbers have also increased on the south coast, these gains have been modest. While the Arctic coastal plain is not included in the TSA, breeding ducks have been surveyed here since 1986. Among the 14 duck species included in the TSA that also occur on the coastal plain, there has been no obvious change in duck numbers over the past 20 years.
Although total breeding duck numbers in Alaska appear to have grown over the last 50 years, the increase in some species has been startling. Wigeon are a prime example. In the late 1950s and early 1960s, Alaska's wigeon population hovered around 100,000 birds or about 5 percent of all wigeon in the TSA. In contrast, between 1998 and 2008 Alaska supported an average of nearly 1 million wigeon or 40 percent of all wigeon in the TSA. Over the same period, Alaska averaged 800,000 green-winged teal or nearly a third of all greenwings in the TSA. Mallards, northern shovelers, and ring-necked ducks have also shown large increases. At one time, shovelers and ringnecks barely registered as breeding ducks in Alaska. Today their numbers average around 600,000 birds and 70,000 birds, respectively.
Populations of other duck species have been stable in Alaska, while these birds have suffered declines in other regions. In the early 1970s, there were 6 million pintails in the TSA. Today their numbers are less than half that. Yet, Alaska's pintail numbers have shown little change since the 1950s, and a third of all the pintails in the TSA now occur here on average. Scaup are a similar example. Lesser scaup that breed in Canada's western boreal forest and prairie parklands have substantially declined since the 1970s. Fortunately, Alaska's lesser scaup, which breed mostly in the state's interior, have been stable or have declined only slightly. Finally, 75 percent of North America's greater scaup breed in western Alaska, where their population is unchanged from the 1970s.
So what's responsible for the surge in Alaska's breeding duck counts? In 1977, the U.S. Fish and Wildlife Service began using a new type of aircraft, the turbine Beaver, to survey Alaska's waterfowl. The Beaver was quieter and provided better visibility for both pilots and observers. Not surprisingly, the new aircraft produced an immediate increase in duck counts. This suggests that prior to the switch in aircraft, Alaska's duck populations were underestimated.
The use of different planes before and after 1977 also complicates efforts to measure the growth of breeding duck populations in the state. Are increases in Alaska duck numbers real or simply the result of using a better plane? To account for the change in aircraft, we need to break the survey into two time periods: 1957-1976 and 1977-2008. If a species had population growth during both time periods, we can reasonably assume that its numbers have grown over the past 50 years. Mallards, wigeon, green-winged teal, and shovelers all increased from 1957 to 1976 and from 1977 to 2008, indicating that the growth of these populations was real. Pintail, scaup, and canvasback numbers remained stable during both time periods. Overall, Alaska's dabbling duck populations have significantly increased, while diving duck populations have held their own despite losing ground elsewhere across the continent.
Why have Alaska's dabbling duck populations increased? One thing we know is the state has gotten warmer. Between 1949 and 2007, the state's average temperature increased by 3.4 degrees Fahrenheit. Temperature increases were largest in winter and spring and were similar throughout the state. But the trend toward a warmer climate has not been linear. In 1976, Alaska underwent a dramatic change in climate that produced much warmer temperatures compared to the previous 25 years. These higher temperatures have persisted over the past 30 years. This abrupt warming coincided with a shift in the phase of the Pacific Decadal Oscillation (PDO). The PDO is a long-lived El Niño-like pattern of Pacific climate variability. Cool PDO phases prevailed from 1890-1924 and again from 1947-1976. Warm PDO phases prevailed from 1925-1946 and from 1977 through at least the mid-1990s.
A look at changes in Alaska's dabbling duck populations suggests the increases were larger after the mid-1970s when the state began experiencing warmer springs. Whether this abrupt climate change is responsible for the increase in duck numbers is unknown, but it's certainly possible that an earlier spring has benefited some species by increasing their reproductive success.
While Alaska's waterfowl may benefit from a warming climate (at least in the short term), there may be negative long-term consequences as well. Researchers at the University of Alaska-Fairbanks recently looked at changes in wetland numbers and water area in Alaska's interior between 1950 and 2002. All areas lost wetlands during this period, with some places losing as much as 25 percent of total surface water. A leading cause of these losses could be melting permafrost. When the permafrost layer under these wetlands melts, water drains into the soil rather than pooling on the surface. Another potential cause could be increased evapotranspiration in wetlands during warmer and longer growing seasons. In both cases, the same temperature increases that may have led to larger duck populations may also be leading to less duck habitat.
So far our discussion of Alaska's waterfowl has been limited to duck species counted in the TSA. Of the 15 species of sea ducks that occur in North America, only three are included in the TSA. All the continent's sea duck species breed and winter in Alaska. Four species of eiders (common, king, spectacled, and Steller's) and three species of scoter (black, surf, and white-winged) occur year-round in the state. Unfortunately, many populations of eiders and scoters appear to have declined, including some in Alaska.
While some king eiders breed in the Arctic coastal plain, Alaska sees most of these birds in winter. Continentally, king eiders winter in two distinct populations: one in the Atlantic and one in the Pacific. The entire Pacific population winters in the Bering Sea, mostly along the Alaska Peninsula and Aleutian Islands. During spring, these birds migrate within sight of Point Barrow on their way to breeding grounds in the Canadian Arctic. More than 100,000 of the birds have been counted in a 30-minute period. Roughly 300,000-400,000 king eiders have passed by Point Barrow in recent years, down from 600,000 birds in the 1970s. Unfortunately, reasons for the decline are unknown.
In North America, breeding populations of spectacled and Steller's eiders occur exclusively on Alaska's Arctic coastal plain and Y-K Delta. Both species are listed as threatened under the Endangered Species Act. Breeding populations of spectacled eiders declined by more than 90 percent on the Y-K Delta from the 1970s to the early 1990s, but their numbers now appear stable. In contrast, Steller's eiders have virtually disappeared from the Y-K Delta, and the birds are now largely confined to the Arctic coastal plain. Steller's eiders winter along the Alaska Peninsula and Aleutian Islands. The wintering location of spectacled eiders remained a mystery until 1995, when birds fitted with satellite transmitters finally led biologists to their wintering grounds in the middle of the Bering Sea.
Although Alaska now supports a growing share of the continent's breeding ducks, the state is perhaps best known for its geese. Waterfowl managers recognize 28 goose populations in North America, a quarter of which breed mostly or only in Alaska. The state supports all of the world's tule and Pacific white-fronted geese and 90 percent of all emperor geese. Dusky Canada geese and three subspecies of cackling geese also breed exclusively in Alaska. And 80 percent of the world's Pacific brant breed on the Y-K Delta and Arctic coastal plain.
Long-term changes in the size of Alaska's goose populations have been mostly positive. Pacific white-fronted goose numbers have grown 6 percent per year since 1999, and the population now sits at a record 600,000 birds. In 2008, spring counts of cackling geese on the Y-K Delta were the second highest on record and contributed to a decade-long increase in cackler numbers. But the biggest success story has been the comeback of Aleutian cackling geese. Once threatened with extinction, the Aleutian goose population now numbers more than 100,000 birds. Unfortunately, Alaska's dusky Canada goose population has not fared nearly as well. These geese breed on Alaska's south coast in the Copper River Delta. In 1964, an earthquake uplifted their nesting grounds by more than 6 feet, triggering an expansion of trees and shrubs, which made nesting geese much more susceptible to terrestrial predators. Today, the dusky Canada goose population remains well below desired levels.
Ducks Unlimited has traditionally worked in areas important to waterfowl that have lost large amounts of habitat. In these areas, DU focuses on restoring wetlands and permanently protecting remaining habitat. Alaska is different. Most of its waterfowl habitat remains in pristine condition, and almost all of it is publicly owned and protected. Since traditional habitat programs are not needed in Alaska, DU has sought other approaches to waterfowl conservation in the state. For example, DU has collaborated with federal agencies to map much of Alaska's important waterfowl habitat using satellite imagery. These mapping products can inform policy and land use decisions to the benefit of waterfowl.
And while many of Alaska's waterfowl populations are growing and most of its habitats are intact, important questions remain. Why have sea ducks declined? How will global climate change affect the availability of waterfowl habitat in coastal and interior Alaska? Will oil and gas exploration on the Arctic coastal plain negatively affect molting brant and other waterfowl? In the future, DU and its partners in the Sea Duck, Arctic Goose, and Pacific Coast joint ventures can assist in answering these questions and help ensure a bright future for Alaska's waterfowl.
Dr. Mark Petrie and Dr. Fritz Reid are directors of conservation planning in DU's western region. The authors would like to thank the pilot-biologists of the U.S. Fish and Wildlife Service, whose surveys of Alaska's waterfowl made this article possible.