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Species · BCR 14 · BBS 2025 Release · 1966–2024

Common Merganser In Atlantic Northern Forest

All regionsAtlantic Northern ForestWaterfowl

Common Merganser in Atlantic Northern Forest has surged: up 168% on the route-weighted index since 1969.

+168%Since 1969TrendPercent 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 →
90Routes 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 →
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 SignalsNotable signalsLong-arc shifts the engine flags automatically — sustained declines or increases large enough to stand out from year-to-year noise.Full methodology →

long arc increasecomputed indexTrend sourceWhether the figure is our own computed route-weighted index or an official USGS modeled estimate. The current build labels every trend as computed.Full methodology →

Common Merganser has surged in Atlantic Northern Forest: up 168% on the route-weighted index since 1969.

Common Merganser In Atlantic Northern Forest Population Forecast

If the recent trend holds, Common Merganser in Atlantic Northern Forest is projected to fall about 11% by 2029 — from 0.24 in 2024 to a central estimate of 0.21 (95% range 0.11–0.32). A 5-year backtest shows a typical error of ±23.7%, with 100% of held-out values landing inside the 95% band.

-11%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 →
0.21Projected 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 →
0.11–0.3295% 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 →
±23.7%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, Common Merganser in Atlantic Northern Forest is projected to fall about 11% by 2029 — from 0.24 in 2024 to a central estimate of 0.21 (95% range 0.11–0.32). A 5-year backtest shows a typical error of ±23.7%, with 100% of held-out values landing inside the 95% band.19662029
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 →
20250.200.100.31
20260.210.100.32
20270.210.100.32
20280.210.100.32
20290.210.110.32

Routes In Atlantic Northern Forest

Routes recording Common Merganser in Atlantic Northern Forest.
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 →
HudsonMAINE51995
GreenwoodMAINE42014
HarmonyMAINE42016
CastineMAINE41986
BaxterMAINE41984
WalpoleNEW-HAMPSHIRE42024
North RiverNEW-YORK42007
Bowdoin CtrMAINE32002
WinnMAINE32022
Ft FairfieldMAINE31994
MarlowNEW-HAMPSHIRE32021
GlenNEW-HAMPSHIRE32021
GaysvilleVERMONT32018
Wilson MillsMAINE22024
South ArmMAINE21994
NorthfieldMAINE21979
Moose RiverMAINE22005
CarrabassettMAINE22024
Seboomook LkMAINE22014
GreenvilleMAINE21997
Horse MtnMAINE22010
Jefferson HlNEW-HAMPSHIRE22022
StratfordNEW-HAMPSHIRE22019
SpeculatorNEW-YORK22023
GabrielsNEW-YORK22013

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