BirdAnalyst
Species · Wyoming · BBS 2025 Release · 1966–2024

Common Merganser Population Trend in Wyoming

All statesWaterfowl

Common Merganser in Wyoming has risen sharply: up 51% on the route-weighted index since 1977.

+51%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 →
59Routes In StateSurvey 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 Common Merganser Trends in WyomingNotable 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 risen sharply in Wyoming: up 51% on the route-weighted index since 1977.

Common Merganser Population Forecast in Wyoming

If the recent trend holds, Common Merganser in Wyoming is projected to rise about 209% by 2029 — from 0.15 in 2024 to a central estimate of 0.45 (95% range 0.00–0.94). A 5-year backtest shows a typical error of ±64.6%, with 100% of held-out values landing inside the 95% band.

+209%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 →
0.45Projected 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 →
0.00–0.9495% 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 →
±64.6%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 Wyoming is projected to rise about 209% by 2029 — from 0.15 in 2024 to a central estimate of 0.45 (95% range 0.00–0.94). A 5-year backtest shows a typical error of ±64.6%, with 100% of held-out values landing inside the 95% band.19702029
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 →
20250.460.000.94
20260.460.000.94
20270.460.000.94
20280.450.000.94
20290.450.000.94

Common Merganser Survey Routes in Wyoming

Routes recording Common Merganser in Wyoming.
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 →
Hayden Val3019861985
Harmony2120221988
Yellowstone2020221987
Colter Bay 21620232021
Ne Entrance920211993
Moran920162016
Mammoth720181982
Green River719841977
Nowood620241998
Seedskadee420161995
Caballa Crk420082008
Seely 2320082006
Riverside320231993
Clark319921990
Alpine320221992
Mayoworth320101984
Boulder320172017
Rawlins 2320232023
Mtn View320242023
Rock River320221996
Cody219901983
Colter Bay219981970
Dwyer219921992
Mckinnon219861977
Tensleep220232009

Common Merganser Population Trend in Other States

alaskaarizonacaliforniacoloradoconnecticutidahomainemarylandmassachusettsmichiganminnesotamontananevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-dakotaohiooregonpennsylvaniasouth-dakotautahvermontvirginiawashingtonwest-virginiawisconsin

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