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Species · BCR 12 · BBS 2026 Release · 1966–2025

Brown Thrasher In Boreal Hardwood Transition

All regionsBoreal Hardwood TransitionForest birds

Brown Thrasher in Boreal Hardwood Transition has fallen sharply: down 66% on the route-weighted index since 1968.

-66%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 →
123Routes 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 →
59YearsYears 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 →

Brown Thrasher has fallen sharply in Boreal Hardwood Transition: down 65% on the route-weighted index since 1968.

Brown Thrasher In Boreal Hardwood Transition Population Forecast

If the recent trend holds, Brown Thrasher in Boreal Hardwood Transition is projected to fall about 78% by 2030 — from 1.0 in 2025 to a central estimate of 0.22 (95% range 0.00–1.2). A 5-year backtest shows a typical error of ±69.5%, with 80% of held-out values landing inside the 95% band.

-78%Change by 2030TrendPercent 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 →
0.22Projected 2030 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–1.295% 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 →
±69.5%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, Brown Thrasher in Boreal Hardwood Transition is projected to fall about 78% by 2030 — from 1.0 in 2025 to a central estimate of 0.22 (95% range 0.00–1.2). A 5-year backtest shows a typical error of ±69.5%, with 80% of held-out values landing inside the 95% band.19662030
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 →
20260.400.001.4
20270.360.001.3
20280.310.001.3
20290.270.001.2
20300.220.001.2

Routes In Boreal Hardwood Transition

Routes recording Brown Thrasher 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 →
RiggsvilleMICHIGAN102019
Sand LakeMICHIGAN92025
HarriettaMICHIGAN72025
IshpemingMICHIGAN52025
Bear LakeMICHIGAN42025
IronsMICHIGAN41989
Brush CreekMICHIGAN42016
SkeelsMICHIGAN42015
Red OakMICHIGAN42022
Cedar RunMICHIGAN41994
Union TwpWISCONSIN42025
Brocky LakeMICHIGAN32025
PickfordMICHIGAN32024
Beaver LakeMICHIGAN32011
Hiawatha NfMICHIGAN32025
GooseneckMICHIGAN32010
WarroadMINNESOTA32025
GreenbushMINNESOTA32025
Iron RiverWISCONSIN32025
MinongWISCONSIN32025
Washington IWISCONSIN32024
BerglandMICHIGAN22019
Ned LakeMICHIGAN22022
Maple GroveMICHIGAN22025
CunardMICHIGAN22019

Source: USGS North American Breeding Bird Survey, retrieved 2026-08-14.