BirdAnalyst
Species · BCR 28 · BBS 2026 Release · 1966–2025

Common Merganser In Appalachian Mountains

All regionsAppalachian MountainsWaterfowl

Common Merganser in Appalachian Mountains has surged: up 23× on the route-weighted index since 1977.

23×Since 1977TrendPercent 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 →
105Routes 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 →
49YearsYears 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 Common Merganser in Appalachian Mountains. See the full index history below.

Common Merganser In Appalachian Mountains Population Forecast

If the recent trend holds, Common Merganser in Appalachian Mountains is projected to stay roughly flat through 2030, near 0.20 (95% range 0.02–0.38). A 5-year backtest shows a typical error of ±42.4%, with 100% of held-out values landing inside the 95% band.

+0%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 →
0.20Projected 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 →
0.02–0.3895% 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 →
±42.4%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 Appalachian Mountains is projected to stay roughly flat through 2030, near 0.20 (95% range 0.02–0.38). A 5-year backtest shows a typical error of ±42.4%, with 100% of held-out values landing inside the 95% band.19712030
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 →
20260.180.000.36
20270.190.010.36
20280.190.010.37
20290.190.010.37
20300.200.020.38

Routes In Appalachian Mountains

Routes recording Common Merganser in Appalachian Mountains.
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 →
Natural BridVIRGINIA202025
StollingsWEST-VIRGINIA122018
RushPENNSYLVANIA92024
BerwickPENNSYLVANIA91993
EldredPENNSYLVANIA82015
Pocono SummitPENNSYLVANIA82024
LisleNEW-YORK62007
DaileyWEST-VIRGINIA52025
SusquehannaPENNSYLVANIA42023
Yellow SpgWEST-VIRGINIA42018
JenningsMARYLAND32024
LynchPENNSYLVANIA32019
RasselasPENNSYLVANIA32014
ArnotPENNSYLVANIA32004
Mawr GlenPENNSYLVANIA32025
WallerPENNSYLVANIA32018
KittanningPENNSYLVANIA32019
New RinggoldPENNSYLVANIA32012
WyalusingPENNSYLVANIA32022
WilliamsportMARYLAND22022
CobleskillNEW-YORK22015
LaurensNEW-YORK22024
CentervilleNEW-YORK22005
S VandaliaNEW-YORK22016
BetulaPENNSYLVANIA22019

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