BirdAnalyst
Species · BBS 2025 Release · 1966–2024

Gadwall

AnatidaeWaterfowlMareca strepera

Gadwall has surged: up 178% on the route-weighted index since 1969.

+178%Since 1969TrendPercent change in the route-weighted abundance index between a smoothed baseline window and the most recent one. It tracks direction, not absolute population.Full methodology →
618RoutesSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
57Years SurveyedYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

About the Gadwall

The Gadwall (Mareca strepera) is a North American member of the Ducks, Geese & Waterfowl (Anatidae). In this analysis it is grouped with the waterfowl.

Size
12–43.5 in long (30–110 cm) — a medium to large waterfowl (typical for the family)
Habitat
Lakes, ponds, rivers, marshes and sheltered coastal waters.
Diet
Aquatic plants, seeds and invertebrates, dabbled at the surface or dived for.
Range
Recorded on 618 Breeding Bird Survey routes across 31 states, most concentrated in the Great Basin.
Family
Anatidae · Waterfowl

Notable Gadwall TrendsNotable signalsLong-arc shifts the engine flags automatically — sustained declines or increases large enough to stand out from year-to-year noise.Full methodology →

long arc increasecomputed indexTrend sourceWhether the figure is our own computed route-weighted index or an official USGS modeled estimate. The current build labels every trend as computed.Full methodology →

Gadwall has surged in surveyed states: up 178% on the route-weighted index since 1969.

Gadwall Population Forecast

If the recent trend holds, Gadwall is projected to rise about 87% by 2029 — from 0.45 in 2024 to a central estimate of 0.84 (95% range 0.46–1.2). A 5-year backtest shows a typical error of ±100.5%, with 0% of held-out values landing inside the 95% band.

+87%Change by 2029TrendPercent change in the route-weighted abundance index between a smoothed baseline window and the most recent one. It tracks direction, not absolute population.Full methodology →
0.84Projected 2029 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.46–1.295% range95% rangeThe 95% uncertainty band around the projection at the forecast horizon. The true value should land inside it most of the time.Full methodology →
±100.5%Backtest errorBacktest errorTypical error when we hold out the most recent years, forecast them, and compare to what actually happened. Lower means a more trustworthy projection.Full methodology →
If the recent trend holds, Gadwall is projected to rise about 87% by 2029 — from 0.45 in 2024 to a central estimate of 0.84 (95% range 0.46–1.2). A 5-year backtest shows a typical error of ±100.5%, with 0% of held-out values landing inside the 95% band.19672029
Projection of the recent trend (dashed) with 80/95% bands — a projection, not a prediction. Habitat, climate, and land use are not modeled.
YearProjected indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →95% low95% rangeThe 95% uncertainty band around the projection at the forecast horizon. The true value should land inside it most of the time.Full methodology →95% high95% rangeThe 95% uncertainty band around the projection at the forecast horizon. The true value should land inside it most of the time.Full methodology →
20250.800.421.2
20260.810.431.2
20270.820.441.2
20280.830.451.2
20290.840.461.2

Where the Gadwall Is Detected

BBS routes recording Gadwall, sized by most recent count.

Gadwall Population Trend by State

Gadwall population trend by state.
TrendPercent change in the route-weighted abundance index between a smoothed baseline window and the most recent one. It tracks direction, not absolute population.Full methodology →Baseline yearThe first year of the smoothed window the trend is measured from. An earlier baseline means a longer record stands behind the number.Full methodology →Survey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
Alaska-87%19898
Arizona-73%19873
California11×197357
Colorado+128%197066
Delawareinsufficient datan/a3
Idaho+162%197328
Illinoisinsufficient datan/a2
Iowainsufficient datan/a2
Kansas-95%19707
Massachusettsinsufficient datan/a1
Michiganinsufficient datan/a3
Minnesota-29%197821
Missouriinsufficient datan/a2
Montana-7%197269
Nebraska-38%196915
Nevada+74%197123
New Jerseyinsufficient datan/a1
New Mexico-2%197813
New Yorkinsufficient datan/a3
North Dakota+267%196949
Oklahomainsufficient datan/a2
Oregon+473%197137
Pennsylvaniainsufficient datan/a1
Rhode Islandinsufficient datan/a1
South Dakota+7%196949
Texas-30%197912
Utah-8%198135
Vermontinsufficient datan/a1
Washington+40%197530
Wisconsininsufficient datan/a7
Wyoming+167%197167

Gadwall Population Trend by Region

Bird Conservation Regions are the ecological unit for trends.

Gadwall population trend by Bird Conservation Region.
TrendPercent change in the route-weighted abundance index between a smoothed baseline window and the most recent one. It tracks direction, not absolute population.Full methodology →Baseline yearThe first year of the smoothed window the trend is measured from. An earlier baseline means a longer record stands behind the number.Full methodology →Survey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
Northern Pacific Rainforest+30%198216
Great Basin+958%1970117
Northern Rockies+463%197489
Prairie Potholes+137%196992
Sierra Nevada-5%19766
Southern Rockies / Colorado Plateau+945%197071
Badlands and Prairies+226%196990
Shortgrass Prairie-55%197043
Central Mixed Grass Prairie-79%196917
New England / Mid-Atlantic Coast-67%19729
Coastal California+43%197630

Gadwall Conservation Status

Our route-weighted index shows it up about 178% since 1969.

Source: USGS North American Breeding Bird Survey, retrieved 2026-05-22. Trend is a route-weighted relative-abundance index, not an absolute population.