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Species · Wisconsin · BBS 2025 Release · 1966–2024

Red-breasted Merganser Population Trend in Wisconsin

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Red-breasted Merganser in Wisconsin has collapsed: down 90% on the route-weighted index since 1969.

-90%Since 1969TrendPercent 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 →
4Routes 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 →
27YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Red-breasted Merganser Trends in WisconsinNotable 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 declinecomputed 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 →

Red-breasted Merganser has collapsed in Wisconsin: down 89% on the route-weighted index since 1969.

Red-breasted Merganser Population Forecast in Wisconsin

If the recent trend holds, Red-breasted Merganser in Wisconsin is projected to stay roughly flat through 2016, near 0.00 (95% range 0.00–0.28). A 5-year backtest shows a typical error of ±499.6%, with 100% of held-out values landing inside the 95% band.

n/aChange by 2016TrendPercent 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 →
0.00Projected 2016 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–0.2895% 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 →
±499.6%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, Red-breasted Merganser in Wisconsin is projected to stay roughly flat through 2016, near 0.00 (95% range 0.00–0.28). A 5-year backtest shows a typical error of ±499.6%, with 100% of held-out values landing inside the 95% band.19672016
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 →
20120.000.000.28
20130.000.000.28
20140.000.000.28
20150.000.000.28
20160.000.000.28

Red-breasted Merganser Survey Routes in Wisconsin

Routes recording Red-breasted Merganser in Wisconsin.
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 →
Washington I220111967
Casco120082008
Wausaukee119831983
Bayfield119991999

Red-breasted Merganser Population Trend in Other States

alaskamainemichiganminnesota

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