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

Brewer's Blackbird In Boreal Hardwood Transition

All regionsBoreal Hardwood TransitionGeneralists

Brewer's Blackbird in Boreal Hardwood Transition has collapsed: down 78% on the route-weighted index since 1968.

-78%Since 1968TrendPercent 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 →
98Routes 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 →
58YearsYears 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 →

Brewer's Blackbird has collapsed in Boreal Hardwood Transition: down 78% on the route-weighted index since 1968.

Brewer's Blackbird In Boreal Hardwood Transition Population Forecast

If the recent trend holds, Brewer's Blackbird in Boreal Hardwood Transition is projected to stay roughly flat through 2029, near 0.54 (95% range 0.00–2.3). A 5-year backtest shows a typical error of ±36.9%, with 100% of held-out values landing inside the 95% band.

+1%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 →
0.54Projected 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 →
0.00–2.395% 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 →
±36.9%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, Brewer's Blackbird in Boreal Hardwood Transition is projected to stay roughly flat through 2029, near 0.54 (95% range 0.00–2.3). A 5-year backtest shows a typical error of ±36.9%, with 100% of held-out values landing inside the 95% band.19662029
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 →
20250.810.002.6
20260.740.002.5
20270.670.002.4
20280.600.002.4
20290.540.002.3

Routes In Boreal Hardwood Transition

Routes recording Brewer's Blackbird 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 →
Lake CityMICHIGAN382001
BemidjiMINNESOTA241979
ShanagoldenWISCONSIN171984
GreenbushMINNESOTA122024
CathroMICHIGAN101990
NebishMINNESOTA92023
Amnicon FallsWISCONSIN92018
Ned LakeMICHIGAN82015
HermanMICHIGAN81997
RacoMICHIGAN81990
MareniscoMICHIGAN71995
Brocky LakeMICHIGAN71987
Red OakMICHIGAN72007
DebsMINNESOTA72013
TahquamenonMICHIGAN61990
Pleasant Valley 2MICHIGAN62005
Wigwam BayMINNESOTA61995
WaskishMINNESOTA61997
Tamarac NwrMINNESOTA61992
IrmaWISCONSIN62010
Crystal FlsMICHIGAN52017
Pine RiverMINNESOTA52024
HovlandMINNESOTA51983
Island LakeMINNESOTA51995
Nett LakeMINNESOTA52024

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