BirdAnalyst
Species · New Hampshire · BBS 2025 Release · 1966–2024

Hooded Merganser Population Trend in New Hampshire

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Hooded Merganser in New Hampshire has edged up: up 15% on the route-weighted index since 1982.

+15%Since 1982TrendPercent 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 →
18Routes 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 →
38YearsYears 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 New HampshireNotable 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 New Hampshire. See the full index history below.

Hooded Merganser Population Forecast in New Hampshire

If the recent trend holds, Hooded Merganser in New Hampshire is projected to stay roughly flat through 2029, near 0.09 (95% range 0.00–0.27). A 5-year backtest shows a typical error of ±59%, with 100% of held-out values landing inside the 95% band.

-7%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 →
0.09Projected 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 →
0.00–0.2795% 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 →
±59%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 New Hampshire is projected to stay roughly flat through 2029, near 0.09 (95% range 0.00–0.27). A 5-year backtest shows a typical error of ±59%, with 100% 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 →
20250.090.000.28
20260.090.000.28
20270.090.000.28
20280.090.000.28
20290.090.000.27

Hooded Merganser Survey Routes in New Hampshire

Routes recording Hooded Merganser in New Hampshire.
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 →
Franconia420141996
Dixville Notch 2320182018
Epsom219931993
Jeffers Ntch220162016
Dixvil Notch220131988
Fitzwilliam120221990
Dover119921992
East Kingston120172009
Strafford120021987
Canterbury120172017
Gilmantn I W120062006
Wilmot120231982
Mt Chocorua120212021
Walpole120242003
Marlow120231977
Lempster119881986
Jefferson Hl120061967
Milan120241991

Hooded Merganser Population Trend in Other States

alabamaalaskaarkansascoloradoconnecticutidahoillinoisindianaiowakansaskentuckymainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanew-yorknorth-dakotaohiooklahomaoregonpennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasvermontwashingtonwest-virginiawisconsinwyoming

Source: USGS North American Breeding Bird Survey, retrieved 2026-05-22.