BirdAnalyst
Species · BCR 22 · BBS 2025 Release · 1966–2024

Brown Thrasher In Eastern Tallgrass Prairie

All regionsEastern Tallgrass PrairieGeneralists

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 →
276Routes 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 Eastern Tallgrass Prairie: down 54% on the route-weighted index since 1968.

Forecast

If the recent trend holds, Brown Thrasher in Eastern Tallgrass Prairie is projected to stay roughly flat through 2029, near 3.3 (95% range 1.9–4.8). A 5-year backtest shows a typical error of ±13%, with 100% of held-out values landing inside the 95% band.

-2%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 →
3.3Projected 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 →
1.9–4.895% 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 →
±13%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 2029, near 3.3 (95% range 1.9–4.8). A 5-year backtest shows a typical error of ±13%, 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 →
20253.62.25.1
20263.62.15.0
20273.52.04.9
20283.41.94.8
20293.31.94.8

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 →
Mt HamillIOWA182024
WashtaIOWA162014
BedfordIOWA152018
GrantvilleKANSAS152022
LincolnvilleKANSAS152024
LacledeMISSOURI152024
FloraILLINOIS142022
College SpgsIOWA142004
McfallMISSOURI142024
LucerneMISSOURI142021
BelleviewILLINOIS132024
HuntsvilleMISSOURI132024
NorborneMISSOURI132023
WallaceINDIANA122024
StetMISSOURI121995
TrentonMISSOURI112024
BolckowMISSOURI111992
EmdenMISSOURI112024
MurdockNEBRASKA112024
AthensvilleILLINOIS102024
PaysonILLINOIS102024
Red RockIOWA102024
Trading PostKANSAS102024
HamiltonMISSOURI101985
HumboldtNEBRASKA102024

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