Waterfowl Population Status and Trends

722 FW 2
FWM Number
Originating Office
Division of Migratory Bird Management

2.1 Purpose. This chapter describes principal procedures for coordinating and conducting population and production surveys and reporting the status and trends of waterfowl populations each year. This survey program includes spring and summer breeding ground surveys, primarily for ducks, in Canada and the United States, and inventories on key migration and wintering areas for geese, brant, and swans in the United States and Mexico.

2.2 Constraints. Annual assessments of population status, based on analysis and interpretation of annual survey information, must be completed according to established schedules in order to allow sufficient time for Flyway Councils, U.S. Fish and Wildlife Service (Service) Regulations Committee members, and other interested agencies and organizations to consider pertinent information in the development of early-season and late-season hunting regulations.

2.3 Duck Breeding Populations. Assessments of the status and trend of breeding populations of ducks in North America include the following considerations:

A. Coordination. The Waterfowl Breeding Population Survey is an annual, cooperative effort by the Canadian Wildlife Service (CWS), the Service, and State and Provincial wildlife agencies to estimate the numbers of breeding waterfowl in Canada and the United States. Because of the international nature of this survey, close timing and coordination are required between Canadian and U.S. participants. In the operational survey area (north-central U.S., western Canada, and Alaska), all aerial activities involve American biologists. Ground crews in Canada and the U.S. are comprised of Canadian and American biologists, respectively. All survey areas except Alaska are flown by pilot/biologists assigned to the Office of Migratory Bird Management (MBMO). In Alaska, survey activities are solely under the supervision of Region 7. Ground crew participants in the U.S. depend mostly on Regional involvement, with some assistance by MBMO staff. Regional support, both manpower and vehicles, is guided by the direction of the Service Director in an annual memorandum (usually forwarded each August) listing particular assistance requirements by Region.

B. Data Collection. The survey is conducted in May and early June, primarily from the air, using 71,100 km (44,200 mi) of transects in over 50 strata (geographic regions) throughout central Canada, north-central U.S., and Alaska. A subsample of these aerial transects is surveyed by ground crews to correct for the visibility bias inherent in aerial surveys. Using air and ground counts from the same transects, a visibility correction factor (VCF) is estimated for each species within each crew area (group of strata). The estimated number of breeding waterfowl within a stratum is the product of the area of the stratum, the density of birds seen from the air, and the VCF. The total population of a species is estimated by summing population estimates over all strata in the survey. Currently, several cooperating States also conduct similar surveys and expanded coverage in eastern Canada, the northeastern U.S., and the Pacific Northwest has begun on an experimental basis. A detailed description of the methods is contained in "Standard Operating Procedures for Aerial Breeding Ground Population and Habitat Surveys in North America," U.S. Department of the Interior, Fish and Wildlife Service and Environment Canada, Canadian Wildlife Service, 1987. The handbook (722 FW) is available from the MBMO.

C. Data Entry, Storage, and Analyses. Survey crews gather information and enter data into computer files and field forms, conduct initial edits, and provide preliminary interpretation of results. Information is forwarded from each crew area to MBMO staff in Laurel, Maryland, where biologists, program analysts, and statisticians compile the data, prepare a series of final edits, and analyze the entire data set for annual changes or long-term trends in status of duck populations, by species.

D. Results of Surveys. Results are summarized for the entire survey area (generally, in early July) in an administrative report, "Trends in Duck Breeding Populations." Results are also available in a later Service publication, "Waterfowl Population Status 199_" (symbol FWS-1688, published on July 25 of each year). These reports are distributed widely to interested agencies and organizations and are available to the public.

2.4 Duck Production. Assessments of duck production in North America include the following considerations:

A. Coordination. This July Production Survey is reduced in scope compared to the earlier Waterfowl Breeding Population Survey, and consequently, requires less coordination and participation. Air crews that conducted the May survey also complete the July production survey, generally in the same crew area. Regional participation is outlined by an annual memorandum from the Director.

B. Data Collection. Aerial crews fly over 49,400 km (30,700 mi) of transects in portions of Canada and in the north-central States to obtain information on duck production. Because of problems associated with censusing duck broods from the ground, these counts from aircraft are not corrected for visibility, and broods are not identified to species. This yields an index to annual production of ducks in the surveyed areas. Details of these methods are described in the Handbook (722 FW).

C. Data Entry, Storage, and Analyses. Following data entry, editing, and preliminary interpretation at the field level, information is forwarded to MBMO staff in Laurel, Maryland. After additional edits, annual change and trend information is evaluated for key production indices.

D. Results of Surveys. Results are summarized for the entire survey area in an administrative report, "Waterfowl Population Status 199_." Results are also presented at a series of meetings and public hearings, July - August, in association with the early and late-season regulations development process.

2.5 Goose, Brant, and Swan Populations and Production. Assessments of the population status and outlook for production of major goose, brant, and swan populations include the following considerations:

A. Coordination. Efforts to monitor the population status of geese, brant, and swans involve survey activities extending from arctic Canada and Alaska, south through the U.S. and into Mexico. As a result, survey responsibilities and coordination requirements depend on the particular survey program being undertaken. Some activities are directed solely by individual States, or a combination of States within a Flyway, while others involve a combination of Government and non-government agencies and organizations in Canada, the U.S., and Mexico. A more detailed listing of responsibilities, survey participants, and coordination requirements can be found in respective procedure instructions for individual surveys, which may be obtained from MBMO.

B. Data Collection. The status of 23 populations of geese, brant, and swans is monitored annually through various survey programs (Appendix 1). The primary source of population information is fall and winter surveys that provide annual estimates of numbers for most geese, brant, and swans in North America. Other sources of information on population status and production outlook include: harvest surveys that provide age- ratio data as an index to production, regional banding and/or color-marking programs that monitor migration, survival, and distribution patterns, and satellite imagery of snow conditions, aerial reconnaissance of arctic habitats, and local weather reports that are used to track annual breeding conditions and to provide an annual assessment of expected recruitment for most populations.

C. Data Entry, Storage, and Analyses. Generally, data are entered at the field level and, depending on the particular survey, stored and analyzed at the respective field or Regional Office or forwarded to MBMO staff.

D. Results of Surveys. Results of each survey are usually presented in individual survey reports, prepared by survey participants. However, combined results of these survey efforts are summarized and discussed in the "Waterfowl Population Status 199_." This report, described earlier, receives widespread distribution throughout the waterfowl management community and is available to the public.

Attachments (Exhibits, Amendments, etc)