Waterfowl Breeding Population and Habitat Survey

• General facts
• How waterfowl populations are estimated
  • Traditional survey area
  • Eastern survey area
• Uses of data from the waterfowl breeding population and habitat survey

The Waterfowl Breeding Population and Habitat Survey (WBPHS), also known as the May Survey, was started in 1955 and is the longest-running and most spatially-extensive waterfowl survey in the world. It is run jointly by the United States Fish and Wildlife Service (USFWS) and Environment and Climate Change Canada's Canadian Wildlife Service (CWS).

The objective of the survey is to estimate trends and population size for the most common species of waterfowl found in inland habitats of the survey area (Table 1).

Here are some facts about the Waterfowl Breeding Population and Habitat Survey and uses of the data collected.

General facts

The Waterfowl Breeding Population and Habitat Survey covers more than 3.6 million km² of the northern United States and Canada, and includes much of the primary waterfowl nesting areas in mid-continent and eastern North America (Figure 1).

It is divided into two survey areas: The Traditional Survey Area, which covers the prairies of western Canada and north-central USA, much of the Canadian western boreal, part of Ontario, and some tundra areas in Alaska, and the Eastern Survey Area, which covers much of Ontario, Quebec, the Atlantic Provinces, Maine, and part of New York (Figure 1). The Traditional Survey is comprised of an extensive fixed-wing aerial survey (USFWS) accompanied by ground surveys (CWS), while the Eastern Survey involves fixed-wing (USFWS) and helicopter components (CWS).

Surveys begin during the early phases of breeding in early May in southern portions of both survey areas, and mid-May to early-June in northern areas. The exact survey timing varies annually according to latitude- and weather-related factors such as migration patterns, breeding phenology, and timing of ice break-up.

Information on the number of ponds in the Prairies relates waterfowl populations to habitat conditions and allows predictions of the current year's breeding success.

How waterfowl populations are estimated

Traditional survey area

The Traditional Survey Area has been monitored since 1955. In this area, the USFWS fly aerial transects in fixed-wing aircraft and observers identify and record the number of waterfowl and ponds seen. To correct for birds missed by the air crews, counts are combined with intensive ground surveys, conducted by CWS, on a subset of segments in Alberta, Saskatchewan, and Manitoba. These are used to estimate the proportion of waterfowl and ponds that are detected from the air and calculate annual visibility correction factors. In some of the more remote boreal areas, fixed-wing counts are corrected for visibility using historical correction factors derived from helicopter counts.

Eastern survey area

The WBPHS in the Eastern Survey Area evolved from two independent surveys initiated in the 1990s to cover a large portion of eastern Canada. These surveys were integrated in 2004, and the survey in the Eastern Survey Area is now composed of a network of 314 plots (5x5km) surveyed in Ontario, Quebec, New Brunswick, Nova Scotia, and Newfoundland and Labrador by helicopter by Canadian Wildlife Service and a network of aerial transects surveyed by fixed-wing aircraft by USFWS (Figure 1). There is no ground component in the Eastern Survey Area due to the remoteness of areas surveyed.

Detection probabilities are derived using two approaches that take advantage of the very high detection from helicopter surveys: 1) in strata that contain both helicopter plots and fixed-wing transects, detection from the helicopter plots is assumed to be 100% for birds that are available at the time of the survey and differences in the estimated mean population size for each survey platform are used to provide a direct estimate of survey level differences; 2) in strata that contain only fixed-wing transects, a double-counting procedure is used where a helicopter survey of a segment of the transect is flown shortly after the fixed-wing aircraft has completed it. Counts from strata that only contain helicopter plots are assumed unbiased and no correction for detection is done.

Uses of data from the waterfowl breeding population and habitat survey

Waterfowl Breeding Population and Habitat Survey data are the biological foundation for the establishment of migratory game birds hunting regulations for most species in Canada and the United States. Data on population size and trends from the survey are published in the Canadian Wildlife Service's annual population status report on migratory game birds in Canada and the U.S. Fish and Wildlife Service's annual Trends in Duck Breeding Populations report. These documents are used as a reference during the annual regulatory review process. Another major use of the data is for the international reporting of waterfowl population status to flyway councils.

Waterfowl Breeding Population and Habitat Survey data are also used to support landscape planning, Environmental Assessment and research on waterfowl. A number of non-game species (e.g. loons and grebes; Table 1) are also recorded on this survey, providing some information on their status.