Though largely invisible to the public, a small army of federal employees each spring descends on the continent's most productive waterfowl lands to undertake a rigorous counting of North American breeding ducks.
The waterfowl survey has generally been conducted the same way since 1955, and its methodology to a large extent had its origins in Minnesota, under the guidance of the late Art Hawkins, among other U.S. Fish and Wildlife Service waterfowl biologists. (Minnesota conducts its own spring waterfowl survey, this year finding overall duck abundance up 47 percent. More below.)
Involved in the federal survey are specially trained pilots who fly their aircraft low and slow, while keeping an eye peeled for antennas, birds and other objects that often share the airspace 150 feet above terra firma. Traveling at only 90 miles an hour, the pilots also count ducks and geese on the left side of the plane.
An observer in the plane, meanwhile, tallies waterfowl on the right side, while also chronicling the number of ponds that lie below.
"Counting ducks is not for the faint of heart," said Terry Liddick, a Fish and Wildlife Service biologist-pilot stationed in Spearfish, S.D.
This spring, Liddick, along with observer and fellow service employee Dave Fronczak, flew "transects" over the eastern Dakotas — exacting east-west routes that have been trekked by waterfowl surveyors for more than a half-century.
Also during May, other Fish and Wildlife Service surveyors flew over duck- and goose-producing regions as far north as Alaska, while Canadian Wildlife Service teams fanned out across Manitoba, Saskatchewan and other provinces.
Information gleaned from the counts is used to assess individual waterfowl species, perhaps mallards mostly, and is tabulated so population fluctuations can be monitored. Hunters' waterfowl limits can be affected by the survey results.