BirdAnalyst
Species · Oregon · BBS 2025 Release · 1966–2024

Common Merganser Population Trend in Oregon

All statesWaterfowl

Common Merganser in Oregon has declined: down 28% on the route-weighted index since 1971.

-28%Since 1971TrendPercent 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 →
64Routes 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 →
55YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Common Merganser Trends in OregonNotable 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 Common Merganser in Oregon. See the full index history below.

Common Merganser Population Forecast in Oregon

If the recent trend holds, Common Merganser in Oregon is projected to rise about 30% by 2029 — from 0.28 in 2024 to a central estimate of 0.36 (95% range 0.00–1.5). A 5-year backtest shows a typical error of ±355.9%, with 100% of held-out values landing inside the 95% band.

+30%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 →
0.36Projected 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 →
0.00–1.595% 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 →
±355.9%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, Common Merganser in Oregon is projected to rise about 30% by 2029 — from 0.28 in 2024 to a central estimate of 0.36 (95% range 0.00–1.5). A 5-year backtest shows a typical error of ±355.9%, with 100% of held-out values landing inside the 95% band.19682029
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 →
20250.360.001.5
20260.360.001.5
20270.360.001.5
20280.360.001.5
20290.360.001.5

Common Merganser Survey Routes in Oregon

Routes recording Common Merganser in Oregon.
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 →
Cool Camp31320132001
Joseph1320241981
Salado1120241980
Bull Run720232008
Sisters620162016
Molalla420211995
Glasgow420182016
Prospect420091999
Dell Spring319821982
Wedderburn320041970
Emigrant Lake 2320192019
Riley Peak220102009
Imnaha220172007
Logdell220221972
Bridgeport220221986
Winberry220131968
Bly 2220112008
Camp Sherman219961975
Mount Vernon220001991
Adrian220081984
Fisher220002000
Newbridge220071998
Myrtle Grove220042004
Salem219981998
Timber120132013

Common Merganser Population Trend in Other States

alaskaarizonacaliforniacoloradoconnecticutidahomainemarylandmassachusettsmichiganminnesotamontananevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-dakotaohiopennsylvaniasouth-dakotautahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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