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Atlantic Flyway Breeding Waterfowl Survey

LIMITATIONS
The survey was designed primarily to estimate breeding population size of mallards, black ducks, wood ducks, and Canada geese. Breeding population estimates for other species encountered during this survey frequently have unacceptably large standard errors.

Estimates most appropriate at the survey-area (11-state) level. Appropriateness and precision decrease as the spatial scale becomes finer, from stratum-level to state-level to stratum-within-state-level estimates.

The survey protocol uses criteria derived in the mid-continent to determine the number of indicated pairs and total indicated birds from count data. The applicability of these criteria to eastern waterfowl populations have not been evaluated.

Correction factors have been suggested for population estimates derived from this survey (Heusmann and Sauer, 1997, 2000). These include a time-of-day correction, especially useful in wood duck and mallard estimates. A correction for aggregations at feeding sites is applicable for mallard estimates. Estimates presented here are uncorrected for time-of-day and feeding-site effects. Although estimates provided are useful in examining population trends or relative changes in populations, they should not be considered absolute measures of abundance, especially for mallards and wood ducks.

POINT OF CONTACT
Anthony Roberts
Wildlife Biologist, Atlantic Flyway
US Fish and Wildlife Service
11510 American Holly Drive, Room 212
Laurel, MD 20708-4038, USA
voice mail: (301) 497-5852
fax:  (301) 497-5885
anthony_roberts@fws.gov

LITERATURE CITED
Heusmann, H. W. and J. R. Sauer. 1997. A survey for mallard pairs in the Atlantic Flyway. Journal of Wildlife Management 61:1191-1198.

Heusmann, H. W. and J. R. Sauer. 2000. The northeast states’ breeding waterfowl population survey. Wildlife Society Bulletin 28:355-364.

PURPOSE
Prior to 1989 no regional survey existed of waterfowl breeding populations in the northeast United States. In 1989, the Atlantic Flyway Technical Section initiated this breeding waterfowl survey in 11 northeast states ranging from New Hampshire to Virginia. The purpose of this survey was to collect breeding population abundance data that would support effective management of eastern waterfowl breeding populations. Prior to this survey (and Federal breeding waterfowl surveys initiated in 1990 in eastern Canada and Maine) eastern waterfowl populations were managed based on data collected for mid-continent populations. This survey was designed primarily to estimate population sizes of mallards (Anas platyrhynchos platyrhynchos), black ducks (Anas rubripes), wood ducks (Aix sponsa), and Canada geese (Branta canadensis), however all observed waterfowl are recorded.

PROCEDURES
During this survey, approximately 1,500 1-km2 plots are surveyed each spring by biologists from participating states. The survey plots are randomly allocated among nearly 20 physiographic strata. Prior to 1993 certain plots were checked annually, while others were reselected each year. In 1993, all plot locations were fixed and plots were surveyed every year. In addition to recording waterfowl observations on each plot, the time of day (twilight or daylight) that each plot is surveyed is recorded. Analyses of survey data indicate that the time of day that a plot is surveyed can significantly affect detection probability.  Since 1993, survey participants have been instructed to survey plots consistently during the twilight or daylight periods from year to year. Sample plots are surveyed in most cases from the ground by either automobile, boat, or on foot.

From 1993 until 2002, only total birds were counted for green-wing teal (Anas crecca), blue-wing teal (A. discors), gadwall (A. strepera), common mergansers (Mergus merganser), hooded mergansers (Lophodytes cucullatus), and mute swans (Cygnus olor). Beginning in 2003, more detailed data were collected for these species, as is done for mallards, black ducks, wood ducks, and Canada geese.

Also in 2003, the formula for calculating total indicated birds (TIB) for Canada geese was changed. Previously, TIBs for Canada geese were calculated as (2 pairs) + singles + grouped birds. In order to have population estimates more comparable to those from other goose surveys and estimates for other species in this survey, the formula was changed to: TIB = 2 (pairs + singles) + grouped birds. As raw data are not currently available to recalculate TIBs for Canada geese for the previous years, population estimates based on both formulae will be presented for at least 5 years to allow comparison. The Division of Migratory Bird Management, USFWS, is responsible for performing data analyses.

More detailed information about survey procedures or analyses of these data can be found in Heusmann and Sauer (1997, 2000).

STATES PARTICIPATING IN THE SURVEY
Vermont
New Hampshire
Massachusetts
Rhode Island
Connecticut
New York
Pennsylvania
New Jersey
Delaware
Maryland
Virginia

DATABASES
Two databases for this survey can be accessed online through the FWS/USGS Migratory Bird Data Center. A count database is available that contains raw waterfowl counts at the sample plot-level. A second database of population estimates is available that contains species-specific, annual population estimates for physiographic strata and state units.

DOWNLOADABLE FIELDS DEFINITION

Field Name

Field Definition

Plot-level Count Database

 

Year

Survey year

State

State in which sample plot is contained

Stratum

Physiographic stratum in which plot is contained (Heusmann and Sauer 1997)

Plot

Plot number

Date

Calendar date on which plot was surveyed

Method

Vehicle used for survey (G: Ground, B: Boat, F: Fixed-wing, H: Helicopter)

CkType

Time of sampling (1: Mid-day, 2: Twilight, 3: Not sampled no wetland habitat)

WetHab

Indicator of presence of wetland habitat on sample plot (Y: yes, N: no)

HandFd

Indicator of the presence of artificial feeding sites on sample plot (Y: yes, N: no)

MALL_TIP

Mallard total indicated pairs

MALL_TIB

Mallard total indicated birds

ABDU_TIP

American black duck total indicated pairs

ABDU_TIB

American black duck total indicated birds

WODU_TIP

Wood duck total indicated pairs

WODU_TIB

Wood duck total indicated birds

GADW_TIP

Gadwall total indicated pairs

GADW_TIB

Gadwall total indicated birds

CAGO_TIP

Canada goose total indicated pairs

CAGO_TIB

Canada goose total indicated birds

BWTE_TIP

Blue-winged teal total indicated pairs

BWTE_ TIB

Blue-winged teal total indicated birds

AGWT_TIP

Green-winged teal total indicated pairs

AGWT_TIB

Green-winged teal total indicated birds

HOME_ TIP

Hooded merganser total indicated pairs

HOME_TIB

Hooded merganser total indicated birds

COME_TIP

Common merganser total indicated pairs

COME_TIB

Common merganser total indicated birds

MUSW_TIP

Mute swan total indicated pairs

MUSW_TIB

Mute swan total indicated birds

OTHERTOT

Total counts of other waterfowl species not listed above

TOTDUCKS Total estimated birds for all selected duck species
   

Estimates Database

 

Year

Survey year

State

State code

Stratum

Physiographic strata code (Heusmann and Sauer 1997)

Species

Four letter alphabetic code for a species (MALL: mallard, ABDU: American black duck, WODU: wood duck, GADW: gadwall, CAGO: Canada goose, BWTE: blue-winged teal, AGWT: green-winged teal, HOME: hooded merganser, COME: common merganser, MUSW: mute swan)

No_plots

Number of plots used in estimation

EST_TIP

Total estimated pairs

SE_TIP

Standard error of total indicated pairs estimate

EST_TIB

Total estimated birds, based on the old (1993-2002)TIB formula

SE_TIB

Standard error of total indicated birds estimate, basedon the old (1993-2002) TIB formula

EST_TIBN Total estimated birds, based on the new (2003 and later) TIB formula
SE_TIBN Standard error of total indicated birds estimate, based on the new (2003 and later) TIB formula

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