BirdAnalyst
Species · BCR 13 · BBS 2026 Release · 1966–2025

Brown Thrasher In Lower Great Lakes / St. Lawrence Plain

All regionsLower Great Lakes / St. Lawrence PlainForest birds

Brown Thrasher in Lower Great Lakes / St. Lawrence Plain has fallen sharply: down 60% on the route-weighted index since 1968.

-60%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 →
86Routes 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 Lower Great Lakes / St. Lawrence Plain: down 60% on the route-weighted index since 1968.

Brown Thrasher In Lower Great Lakes / St. Lawrence Plain Population Forecast

If the recent trend holds, Brown Thrasher in Lower Great Lakes / St. Lawrence Plain is projected to fall about 55% by 2030 — from 1.3 in 2025 to a central estimate of 0.59 (95% range 0.00–1.8). A 5-year backtest shows a typical error of ±61.6%, with 100% of held-out values landing inside the 95% band.

-55%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 →
0.59Projected 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 →
0.00–1.895% 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 →
±61.6%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 Lower Great Lakes / St. Lawrence Plain is projected to fall about 55% by 2030 — from 1.3 in 2025 to a central estimate of 0.59 (95% range 0.00–1.8). A 5-year backtest shows a typical error of ±61.6%, 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 →
20260.710.001.9
20270.680.001.9
20280.650.001.9
20290.620.001.8
20300.590.001.8

Routes In Lower Great Lakes / St. Lawrence Plain

Routes recording Brown Thrasher in Lower Great Lakes / St. Lawrence Plain.
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 →
FowlerNEW-YORK101968
WaddingtonNEW-YORK81998
BranchportNEW-YORK72024
NashvilleNEW-YORK52018
WatertownNEW-YORK52012
OgdensburgNEW-YORK52025
PhiladelphiaNEW-YORK52025
Mt MorrisNEW-YORK42025
CastileNEW-YORK42025
E YoungstownNEW-YORK42025
HarrisvillePENNSYLVANIA42023
North PownalVERMONT42025
SheridanNEW-YORK32025
ByronNEW-YORK32025
ChurchvilleNEW-YORK32025
ParishvilleNEW-YORK32025
PittsfieldOHIO32024
PeruOHIO31978
Valley CityOHIO32017
Slippery RkPENNSYLVANIA31992
DuanesburgNEW-YORK22025
Oriskany FlsNEW-YORK22024
MacdougallNEW-YORK22025
RushvilleNEW-YORK22024
HamburgNEW-YORK22025

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