BirdAnalyst
Species · BCR 22 · BBS 2026 Release · 1966–2025

Brown Thrasher In Eastern Tallgrass Prairie

All regionsEastern Tallgrass PrairieForest birds

Brown Thrasher in Eastern Tallgrass Prairie has fallen sharply: down 54% on the route-weighted index since 1968.

-54%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 →
278Routes 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 Eastern Tallgrass Prairie: down 53% on the route-weighted index since 1968.

Brown Thrasher In Eastern Tallgrass Prairie Population Forecast

If the recent trend holds, Brown Thrasher in Eastern Tallgrass Prairie is projected to stay roughly flat through 2030, near 3.2 (95% range 1.8–4.7). A 5-year backtest shows a typical error of ±14.7%, with 100% of held-out values landing inside the 95% band.

-6%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 →
3.2Projected 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 →
1.8–4.795% 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 →
±14.7%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 Eastern Tallgrass Prairie is projected to stay roughly flat through 2030, near 3.2 (95% range 1.8–4.7). A 5-year backtest shows a typical error of ±14.7%, with 100% 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 →
20263.52.15.0
20273.52.04.9
20283.41.94.8
20293.31.94.7
20303.21.84.7

Routes In Eastern Tallgrass Prairie

Routes recording Brown Thrasher in Eastern Tallgrass Prairie.
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 →
MurdockNEBRASKA192025
Mt HamillIOWA172025
GrantvilleKANSAS152022
LincolnvilleKANSAS152024
FloraILLINOIS142022
College SpgsIOWA142004
HuntsvilleMISSOURI132025
McfallMISSOURI132025
NorborneMISSOURI132023
WallaceINDIANA122024
StetMISSOURI121995
BolckowMISSOURI111992
EmdenMISSOURI112024
JohnsonNEBRASKA112025
ExlineIOWA102025
OhioMISSOURI102025
RensselaerMISSOURI102025
HamiltonMISSOURI101985
ThurstonNEBRASKA102025
HarveysburgOHIO101996
WainwrightOKLAHOMA102013
BelleviewILLINOIS92025
Mascoutah LkILLINOIS92025
Trading PostKANSAS92025
MadisonMISSOURI92024

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