BirdAnalyst
Species · BCR 12 · BBS 2025 Release · 1966–2024

Red-breasted Merganser In Boreal Hardwood Transition

All regionsBoreal Hardwood TransitionWaterfowl

Red-breasted Merganser in Boreal Hardwood Transition has collapsed: down 87% on the route-weighted index since 1969.

-87%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 →
13Routes 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 →
39YearsYears 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 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 Boreal Hardwood Transition: down 87% on the route-weighted index since 1969.

Red-breasted Merganser In Boreal Hardwood Transition Population Forecast

If the recent trend holds, Red-breasted Merganser in Boreal Hardwood Transition is projected to fall about 100% by 2026 — from 0.07 in 2021 to a central estimate of 0.00 (95% range 0.00–0.35). A 5-year backtest shows a typical error of ±498.2%, with 100% of held-out values landing inside the 95% band.

-100%Change by 2026TrendPercent 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 2026 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–0.3595% 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 →
±498.2%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 Boreal Hardwood Transition is projected to fall about 100% by 2026 — from 0.07 in 2021 to a central estimate of 0.00 (95% range 0.00–0.35). A 5-year backtest shows a typical error of ±498.2%, with 100% of held-out values landing inside the 95% band.19672026
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 →
20220.000.000.35
20230.000.000.35
20240.000.000.35
20250.000.000.35
20260.000.000.35

Routes In Boreal Hardwood Transition

Routes recording Red-breasted Merganser in Boreal Hardwood Transition.
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 →
HovlandMINNESOTA52021
GilchristMICHIGAN42014
DebsMINNESOTA41973
BerglandMICHIGAN21993
HermanMICHIGAN21993
WaskishMINNESOTA21994
Washington IWISCONSIN22011
IshpemingMICHIGAN12012
Hubbard LakeMICHIGAN11995
MayfieldMICHIGAN12004
McgregorMINNESOTA11993
BayfieldWISCONSIN11999
WausaukeeWISCONSIN11983

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