BirdAnalyst
Species · BCR 28 · BBS 2025 Release · 1966–2024

Common Merganser In Appalachian Mountains

All regionsAppalachian MountainsWaterfowl

Common Merganser in Appalachian Mountains has surged: up 19× on the route-weighted index since 1977.

19×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 →
99Routes 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 →
48YearsYears 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 Appalachian Mountains: up 19× on the route-weighted index since 1977.

Common Merganser In Appalachian Mountains Population Forecast

If the recent trend holds, Common Merganser in Appalachian Mountains is projected to rise about 33% by 2029 — from 0.14 in 2024 to a central estimate of 0.19 (95% range 0.01–0.37). A 5-year backtest shows a typical error of ±51.5%, with 100% of held-out values landing inside the 95% band.

+33%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 →
0.19Projected 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 →
0.01–0.3795% 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 →
±51.5%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 Appalachian Mountains is projected to rise about 33% by 2029 — from 0.14 in 2024 to a central estimate of 0.19 (95% range 0.01–0.37). A 5-year backtest shows a typical error of ±51.5%, with 100% of held-out values landing inside the 95% band.19712029
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 →
20250.180.000.36
20260.180.000.36
20270.180.000.36
20280.190.010.37
20290.190.010.37

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 →
StollingsWEST-VIRGINIA122018
Natural BridVIRGINIA102023
RushPENNSYLVANIA92024
BerwickPENNSYLVANIA91993
EldredPENNSYLVANIA82015
Pocono SummitPENNSYLVANIA82024
LisleNEW-YORK62007
OneontaNEW-YORK52023
SusquehannaPENNSYLVANIA42023
Yellow SpgWEST-VIRGINIA42018
JenningsMARYLAND32024
LynchPENNSYLVANIA32019
RasselasPENNSYLVANIA32014
ArnotPENNSYLVANIA32004
WallerPENNSYLVANIA32018
KittanningPENNSYLVANIA32019
New RinggoldPENNSYLVANIA32012
WyalusingPENNSYLVANIA32022
WilliamsportMARYLAND22022
CobleskillNEW-YORK22015
LaurensNEW-YORK22024
CentervilleNEW-YORK22005
S VandaliaNEW-YORK22016
BetulaPENNSYLVANIA22019
RoulettePENNSYLVANIA22008

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