BirdAnalyst
Species · BCR 9 · BBS 2025 Release · 1966–2024

Common Merganser In Great Basin

All regionsGreat BasinWaterfowl

Common Merganser in Great Basin has increased: up 42% on the route-weighted index since 1971.

+42%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 →
59Routes 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 →
54YearsYears 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 Great Basin. See the full index history below.

Common Merganser In Great Basin Population Forecast

If the recent trend holds, Common Merganser in Great Basin is projected to stay roughly flat through 2029, near 0.24 (95% range 0.07–0.41). A 5-year backtest shows a typical error of ±81.1%, with 100% of held-out values landing inside the 95% band.

-3%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 →
0.24Projected 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 →
0.07–0.4195% 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 →
±81.1%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 Great Basin is projected to stay roughly flat through 2029, near 0.24 (95% range 0.07–0.41). A 5-year backtest shows a typical error of ±81.1%, with 100% of held-out values landing inside the 95% band.19692029
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 →
20250.230.060.41
20260.230.060.41
20270.240.070.41
20280.240.070.41
20290.240.070.41

Routes In Great Basin

Routes recording Common Merganser in Great Basin.
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 →
Iron GateCALIFORNIA242019
JosephOREGON132024
Dobbin CreekNEVADA102011
RimrockWASHINGTON82023
FallonNEVADA61998
SistersOREGON62016
NighthawkWASHINGTON62024
No CascadesWASHINGTON61996
NewhalemWASHINGTON52024
Iron SpringsIDAHO42019
Dougal ResIDAHO42019
NixonNEVADA42023
BrewsterWASHINGTON42015
LeavenworthWASHINGTON41990
LikelyCALIFORNIA31999
Dell SpringOREGON31982
YakimaWASHINGTON32024
Clear Lk ResCALIFORNIA22004
GiffordIDAHO22017
TriangleIDAHO22024
Magic MtnIDAHO22009
ImnahaOREGON22017
Camp ShermanOREGON21996
AdrianOREGON22008
Bly 2OREGON22011

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