BirdAnalyst
Species · BCR 16 · BBS 2025 Release · 1966–2024

Common Merganser In Southern Rockies / Colorado Plateau

All regionsSouthern Rockies / Colorado PlateauWaterfowl

Common Merganser in Southern Rockies / Colorado Plateau has surged: up 235% on the route-weighted index since 1975.

+235%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 →
54Routes 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 →
47YearsYears 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 234% 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 11% by 2029 — from 0.24 in 2024 to a central estimate of 0.27 (95% range 0.07–0.47). A 5-year backtest shows a typical error of ±13.5%, 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 →
0.27Projected 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 →
0.07–0.4795% 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 →
±13.5%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 Southern Rockies / Colorado Plateau is projected to rise about 11% by 2029 — from 0.24 in 2024 to a central estimate of 0.27 (95% range 0.07–0.47). A 5-year backtest shows a typical error of ±13.5%, 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 →
20250.260.060.46
20260.260.060.46
20270.260.060.46
20280.270.070.46
20290.270.070.47

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 →
TincupCOLORADO122024
Cochetopa PassCOLORADO92024
WaldenCOLORADO72023
FerronUTAH62021
Rio Grnds RsCOLORADO52024
PaoniaCOLORADO42014
ParlinCOLORADO32023
Dolores RivCOLORADO32018
Groundhog RsCOLORADO32016
Fox CreekCOLORADO32023
South ForkCOLORADO32023
Gold HillCOLORADO32012
JensenUTAH32007
KamasUTAH32015
YampaCOLORADO22018
BufordCOLORADO22024
Lost LakeCOLORADO22023
TarryallCOLORADO22023
GuffeyCOLORADO22018
CortezCOLORADO22007
San LuisCOLORADO22024
Lake City 2COLORADO22023
AnimasCOLORADO21998
AngoraCOLORADO22012
Yellowjacket PassCOLORADO22001

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