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

Common Merganser Population Trend in Utah

All statesWaterfowl

Common Merganser in Utah has declined: down 38% on the route-weighted index since 1995.

-38%Since 1995TrendPercent 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 →
9Routes 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 →
18YearsYears 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 UtahNotable 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 Utah. See the full index history below.

Common Merganser Population Forecast in Utah

If the recent trend holds, Common Merganser in Utah is projected to stay roughly flat through 2029, near 0.03 (95% range 0.00–0.10). A 5-year backtest shows a typical error of ±113.4%, with 80% of held-out values landing inside the 95% band.

n/aChange 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 →
0.03Projected 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 →
0.00–0.1095% 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 →
±113.4%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 Utah is projected to stay roughly flat through 2029, near 0.03 (95% range 0.00–0.10). A 5-year backtest shows a typical error of ±113.4%, with 80% of held-out values landing inside the 95% band.19902029
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 →
20250.030.000.10
20260.030.000.10
20270.030.000.10
20280.030.000.10
20290.030.000.10

Common Merganser Survey Routes in Utah

Routes recording Common Merganser in Utah.
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 →
Ferron620212018
Jensen320072007
Kamas320152004
Neponset Res120031995
Lost Cr. Res120152015
Delta119941994
Hanna120242000
Aneth120102010
Lynn120091990

Common Merganser Population Trend in Other States

alaskaarizonacaliforniacoloradoconnecticutidahomainemarylandmassachusettsmichiganminnesotamontananevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-dakotaohiooregonpennsylvaniasouth-dakotavermontvirginiawashingtonwest-virginiawisconsinwyoming

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