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Species · BCR 10 · BBS 2025 Release · 1966–2024

Hooded Merganser In Northern Rockies

All regionsNorthern RockiesWaterfowl

Hooded Merganser in Northern Rockies has declined: down 39% on the route-weighted index since 1991.

-39%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 →
16Routes In RegionSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
26YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable SignalsNotable 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 Northern Rockies. See the full index history below.

Hooded Merganser In Northern Rockies Population Forecast

If the recent trend holds, Hooded Merganser in Northern Rockies is projected to stay roughly flat through 2029, near 0.02 (95% range 0.00–0.05). A 5-year backtest shows a typical error of ±43.7%, with 80% of held-out values landing inside the 95% band.

n/aChange 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 →
0.02Projected 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 →
0.00–0.0595% 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 →
±43.7%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 Northern Rockies is projected to stay roughly flat through 2029, near 0.02 (95% range 0.00–0.05). A 5-year backtest shows a typical error of ±43.7%, with 80% of held-out values landing inside the 95% band.19772029
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 →
20250.020.000.05
20260.020.000.05
20270.020.000.05
20280.020.000.05
20290.020.000.05

Routes In Northern Rockies

Routes recording Hooded Merganser in Northern Rockies.
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 →
NoxonMONTANA52019
Twin LakesWASHINGTON41999
NaplesIDAHO22023
KalispellMONTANA22015
GlenMONTANA22009
Willow Creek 2MONTANA21994
ClarkWYOMING22018
HarmonyWYOMING21982
Lolo PassIDAHO12008
EllistonMONTANA11991
NinemileMONTANA12024
Omak CreekWASHINGTON12024
LaurierWASHINGTON12021
L Pend O NwrWASHINGTON11997
LovellWYOMING12019
SeedskadeeWYOMING12016

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