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.