BirdAnalyst
Species · Massachusetts · BBS 2026 Release · 1966–2025

Common Merganser Population Trend in Massachusetts

All statesWaterfowl

Common Merganser in Massachusetts has held roughly steady: down 2% on the route-weighted index since 2002.

-2%Since 2002TrendPercent 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 →
6Routes 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 →
18YearsYears 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 MassachusettsNotable 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 Massachusetts. See the full index history below.

Common Merganser Population Forecast in Massachusetts

If the recent trend holds, Common Merganser in Massachusetts is projected to rise about 68% by 2030 — from 0.06 in 2025 to a central estimate of 0.10 (95% range 0.00–0.21). A 5-year backtest shows a typical error of ±104.5%, with 100% of held-out values landing inside the 95% band.

+68%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 →
0.10Projected 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 →
0.00–0.2195% 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 →
±104.5%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, Common Merganser in Massachusetts is projected to rise about 68% by 2030 — from 0.06 in 2025 to a central estimate of 0.10 (95% range 0.00–0.21). A 5-year backtest shows a typical error of ±104.5%, with 100% of held-out values landing inside the 95% band.19892030
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 →
20260.100.000.20
20270.100.000.20
20280.100.000.21
20290.100.000.21
20300.100.000.21

Common Merganser Survey Routes in Massachusetts

Routes recording Common Merganser in Massachusetts.
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 →
Marion119981998
Belchertown120242024
Cummington120112003
Chesterfield120251989
Cummington 2120232017
Hancock120112010

Common Merganser Population Trend in Other States

alaskaarizonacaliforniacoloradoconnecticutidahomainemarylandmichiganminnesotamontananevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-dakotaohiooregonpennsylvaniasouth-dakotautahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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