BirdAnalyst
Species · BCR 16 · BBS 2026 Release · 1966–2025

Common Merganser In Southern Rockies / Colorado Plateau

All regionsSouthern Rockies / Colorado PlateauWaterfowl

Common Merganser in Southern Rockies / Colorado Plateau has surged: up 236% on the route-weighted index since 1975.

+236%Since 1975TrendPercent 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 →
56Routes 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 Southern Rockies / Colorado Plateau: up 236% on the route-weighted index since 1975.

Common Merganser In Southern Rockies / Colorado Plateau Population Forecast

If the recent trend holds, Common Merganser in Southern Rockies / Colorado Plateau is projected to rise about 30% by 2030 — from 0.20 in 2025 to a central estimate of 0.26 (95% range 0.07–0.46). A 5-year backtest shows a typical error of ±19%, with 100% of held-out values landing inside the 95% band.

+30%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 →
0.26Projected 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 →
0.07–0.4695% 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 →
±19%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 Southern Rockies / Colorado Plateau is projected to rise about 30% by 2030 — from 0.20 in 2025 to a central estimate of 0.26 (95% range 0.07–0.46). A 5-year backtest shows a typical error of ±19%, 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 →
20260.260.060.45
20270.260.060.46
20280.260.060.46
20290.260.060.46
20300.260.070.46

Routes In Southern Rockies / Colorado Plateau

Routes recording Common Merganser in Southern Rockies / Colorado Plateau.
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 →
TincupCOLORADO102025
WaldenCOLORADO72023
FerronUTAH62021
Rio Grnds RsCOLORADO52024
BufordCOLORADO42025
PaoniaCOLORADO42014
M Warner ResUTAH42025
ParlinCOLORADO32023
Dolores RivCOLORADO32018
Groundhog RsCOLORADO32016
Fox CreekCOLORADO32023
South ForkCOLORADO32025
Gold HillCOLORADO32012
JensenUTAH32007
KamasUTAH32015
YampaCOLORADO22018
Lost LakeCOLORADO22023
TarryallCOLORADO22023
CortezCOLORADO22007
San LuisCOLORADO22024
ThomasvilleCOLORADO22025
Lake City 2COLORADO22023
DinosaurCOLORADO22025
AnimasCOLORADO21998
AngoraCOLORADO22012

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