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

Brown Thrasher In Boreal Hardwood Transition

All regionsBoreal Hardwood TransitionGeneralists

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

-65%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 →
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 →

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

Forecast

If the recent trend holds, Brown Thrasher in Boreal Hardwood Transition is projected to fall about 76% by 2029 — from 0.92 in 2024 to a central estimate of 0.22 (95% range 0.00–1.2). A 5-year backtest shows a typical error of ±72.4%, with 80% of held-out values landing inside the 95% band.

-76%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 →
0.22Projected 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 →
0.00–1.295% 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 →
±72.4%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, Brown Thrasher in Boreal Hardwood Transition is projected to fall about 76% by 2029 — from 0.92 in 2024 to a central estimate of 0.22 (95% range 0.00–1.2). A 5-year backtest shows a typical error of ±72.4%, with 80% 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 →
20250.400.001.4
20260.360.001.3
20270.310.001.3
20280.270.001.2
20290.220.001.2

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 LakeMICHIGAN82024
HarriettaMICHIGAN72024
Bear LakeMICHIGAN62024
MinongWISCONSIN62024
IronsMICHIGAN41989
Brush CreekMICHIGAN42016
SkeelsMICHIGAN42015
Red OakMICHIGAN42022
Cedar RunMICHIGAN41994
MayfieldMICHIGAN42022
Maple GroveMICHIGAN32023
PickfordMICHIGAN32024
Beaver LakeMICHIGAN32011
Pleasant Valley 2MICHIGAN32024
GooseneckMICHIGAN32010
Union TwpWISCONSIN32024
WausaukeeWISCONSIN32023
Washington IWISCONSIN32024
BashawWISCONSIN32023
BerglandMICHIGAN22019
Ned LakeMICHIGAN22022
Crystal FlsMICHIGAN22024
CunardMICHIGAN22019
CreightonMICHIGAN22019

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