BirdAnalyst
Species · BCR 10 · BBS 2025 Release · 1966–2024

Brown Thrasher In Northern Rockies

All regionsNorthern RockiesGeneralists

Brown Thrasher in Northern Rockies has collapsed: down 93% on the route-weighted index since 1970.

-93%Since 1970TrendPercent 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 →
16Routes 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 →
39YearsYears 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 collapsed in Northern Rockies: down 93% on the route-weighted index since 1970.

Forecast

If the recent trend holds, Brown Thrasher in Northern Rockies is projected to stay roughly flat through 2029, near 0.00 (95% range 0.00–0.15). A 5-year backtest shows a typical error of ±300.7%, with 100% of held-out values landing inside the 95% band.

n/aChange 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 →
0.00Projected 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 →
0.00–0.1595% 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 →
±300.7%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 Northern Rockies is projected to stay roughly flat through 2029, near 0.00 (95% range 0.00–0.15). A 5-year backtest shows a typical error of ±300.7%, with 100% of held-out values landing inside the 95% band.19682029
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 →
20250.000.000.15
20260.000.000.15
20270.000.000.15
20280.000.000.15
20290.000.000.15

Routes In Northern Rockies

Routes recording Brown Thrasher in Northern Rockies.
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 →
Muddy CreekMONTANA32015
LaurelMONTANA22022
MaybellCOLORADO11971
Pryor Mtn.MONTANA12001
CodyWYOMING12005
OttoWYOMING12024
BasinWYOMING11971
NowoodWYOMING12001
ClarkWYOMING12021
LovellWYOMING12024
GeboWYOMING12021
LamontWYOMING11990
LeoWYOMING12001
Green RiverWYOMING11979
Rock SpringsWYOMING11980
SeedskadeeWYOMING11995

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