Anything that dictates waterfowl hunting season lengths, dates and bag limits always catches hunters' attention. Which is why the U.S. Fish and Wildlife Service's annual Waterfowl Breeding Population and Habitat Survey report never goes unnoticed as hunters enter the off-season's final stretch.

In preparation for the report's release, typically in mid-summer, it might be helpful to understand who exactly comes up with these counts, how they do it, and perhaps even more importantly, how the results ultimately impact hunters.

Population perspective

From mid- to late May, the USFWS teams up with the Canadian Wildlife Service and state, provincial and tribal agencies to conduct the survey, which is designed to estimate the breeding waterfowl population's size and to evaluate habitat conditions. Each year, pilot biologists and observers fly fixed-wing airplanes at low altitude (150 feet) on established transect lines throughout the continent's major waterfowl habitat areas. The survey covers more than 55,000 linear miles representing more than 2.1 million square miles of the northern United States and Canada.

How does USFWS come up with final estimates?

The aerial waterfowl count is complemented by surveys ground crews conduct to make up for the fact that some birds aren't visible from the air. It's easy to imagine, for example, that large, bright canvasbacks are much easier to see than small, cryptically colored green-winged teal. The disparity between the aerial and ground counts of individual species helps biologists develop visibility correction factors to apply to aerial counts.

First, they use their aerial counts and adjust them based on these visibility correction factors, then extrapolate the sampled transect results to the entire survey area. Over the last 58 years, the result has been an estimate of breeding duck numbers using key nesting areas.

In some of the far northern regions of the traditional survey area, like the Boreal Forest, ground counts simply aren't feasible, as access to the land is extremely limited. In these situations, the USFWS changes its aerial game plan by conducting the visibility surveys along a limited number of transects in helicopters rather than fixed-wing planes. Since the helicopters move slower and offer greater visibility, corrections can be developed from fixed-wing versus helicopter observations.

Important to note is that populations of a number of species, including mallards, northern shovelers, blue-winged and green-winged teal and gadwalls have been, in recent years, higher than the long-term average. Other species, most notably pintails and scaup, are lower than long-term averages.

All about habitat

The term "May ponds" refers to the index of wetland habitat obtained at the same time the birds are counted, hence the Habitat portion of the survey. As a general rule, duck production increases in wet years; so, the number of May ponds along with the count of breeding ducks is an early signal of the coming fall flight. During the 2013 breeding season, many key areas had average to above average precipitation, with the exception being southeastern Canada, south-central Alberta, the northeast U.S. and portions of Montana and the Dakotas. Total pond counts were 35 percent above the long-term average.

The survey results for habitat and waterfowl populations are the basis for the regulations process. The process between the USFWS and states, which set season dates and bag limits, begins within a few weeks after the survey's completion.

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