A summary of waterfowl surveys in northern America shows dramatic fluctuations in populations this season, and during the historic period since 1955.
"The preliminary estimate of total ducks from the 2008 Waterfowl Breeding Population and Habitat Survey was just over 37 million, which is a nine percent decline from last year's estimate, but still 11 percent greater than the 1955-2007 average. In the U.S. and Canadian prairies, population estimates of many species declined; while populations increased in the boreal forest to the north, likely reflecting in part those birds that overflew the prairies because of drier habitat conditions there." Fish and Wildlife Service press release.
There are 50 survey transects within the traditional regions - whichh samples "two million square miles" and is the "largest and most comprehensive survey of its kind in the world" - around the following places:
Alaska - Yukon Territory -Old Crow Flats ¶ C. & N. Alberta - N.E. British Columbia - NWT ¶ N. Saskatchewan - N. Manitoba -W. Ontario ¶ S. Alberta ¶ S. Saskatchewan ¶ S. Manitoba ¶ Montana & western Dakotas ¶ Eastern Dakotas
"Figure 1: Strata and transects of the of the Waterfowl Breeding Population and Habitat Survey
(Yellow = traditional survey area, green = eastern survey area)."
The preliminary report "does not include estimates from surveys conducted by State or Provincial agencies." The extensive wetlands of the Nebraska Sandhills are not considered as a survey area.
Populations were graphically compared for each year since 1955, for these species:
Mallard ¶ Gadwall ¶ American Wigeon ¶ Green-winged Teal ¶ Blue-winged Teal ¶ Northern Shoveler ¶ Northern Pintail ¶ Redhead ¶ Canvasback ¶ Scaup (greater and lesser combined)
The latter portion of the report includes graphs of the trends from 1955 to 2008. Each chart includes a demarcation for the population goal desired according to the North American Waterfowl Management Plan.
There is a constant flux in numbers, with teal showing steady increases in numbers for the past couple of season. While the number of Redheads was up, Canvasback showed a dramatic decline, from above 800,000 to near 500,000 for the survey area considered.
Summary charts for the eastern breeding area are also included, from the period since 1990. This includes summary details with mergansers, the Ring-necked Duck, goldeneyes (common and Barrow's), Bufflehead, and the Black, White-winged and Surf Scoters.
"Trends in Duck Breeding Populations, 1955-2008" was issued in early July.