BirdAnalyst
Species · North Dakota · BBS 2026 Release · 1966–2025

Hooded Merganser Population Trend in North Dakota

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Hooded Merganser in North Dakota has surged: up 811% on the route-weighted index since 1991.

+811%Since 1991TrendPercent 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 →
20Routes In StateSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
33YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Hooded Merganser Trends in North DakotaNotable signalsLong-arc shifts the engine flags automatically — sustained declines or increases large enough to stand out from year-to-year noise.Full methodology →

No notable trend signals for Hooded Merganser in North Dakota. See the full index history below.

Hooded Merganser Population Forecast in North Dakota

If the recent trend holds, Hooded Merganser in North Dakota is projected to fall about 38% by 2030 — from 0.48 in 2025 to a central estimate of 0.30 (95% range 0.06–0.54). A 5-year backtest shows a typical error of ±80.6%, with 40% of held-out values landing inside the 95% band.

-38%Change by 2030TrendPercent 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 →
0.30Projected 2030 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.06–0.5495% 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 →
±80.6%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, Hooded Merganser in North Dakota is projected to fall about 38% by 2030 — from 0.48 in 2025 to a central estimate of 0.30 (95% range 0.06–0.54). A 5-year backtest shows a typical error of ±80.6%, with 40% of held-out values landing inside the 95% band.19682030
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 →
20260.280.030.52
20270.280.040.52
20280.290.040.53
20290.290.050.54
20300.300.060.54

Hooded Merganser Survey Routes in North Dakota

Routes recording Hooded Merganser in North Dakota.
Recent countThe raw number of individuals recorded on this route in its most recent survey year. A single-route tally, not a trend.Full methodology →
Cooperstown420252014
Forman320222011
Carpio320031996
Denbigh320221991
Sheyenne Lk320251998
Lake George220222022
Horsehead Lk220241994
Buchanan220241968
Lakota220052005
Rolla220222014
Niles220131994
Braddock220142014
Montpelier220252012
Lakota 2220252012
Danzig120092003
Emerado120251996
Loraine119891989
Wild Rose120082008
Turtle Mtns120251995
Danzig 2120242024

Hooded Merganser Population Trend in Other States

alabamaalaskaarkansascoloradoconnecticutidahoillinoisindianaiowakansaskentuckymainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanew-hampshirenew-yorkohiooklahomaoregonpennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasvermontwashingtonwest-virginiawisconsinwyoming

Source: USGS North American Breeding Bird Survey, retrieved 2026-08-14.