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Species · BCR 12 · BBS 2026 Release · 1966–2025

Tennessee Warbler In Boreal Hardwood Transition

All regionsBoreal Hardwood TransitionForest birds

Tennessee Warbler in Boreal Hardwood Transition has surged: up 150% on the route-weighted index since 1970.

+150%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 →
63Routes 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 →
56YearsYears 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 increasecomputed 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 →

Tennessee Warbler has surged in Boreal Hardwood Transition: up 150% on the route-weighted index since 1970.

Tennessee Warbler In Boreal Hardwood Transition Population Forecast

If the recent trend holds, Tennessee Warbler in Boreal Hardwood Transition is projected to fall about 37% by 2030 — from 0.49 in 2025 to a central estimate of 0.31 (95% range 0.00–0.70). A 5-year backtest shows a typical error of ±48.6%, with 100% of held-out values landing inside the 95% band.

-37%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 →
0.31Projected 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 →
0.00–0.7095% 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 →
±48.6%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, Tennessee Warbler in Boreal Hardwood Transition is projected to fall about 37% by 2030 — from 0.49 in 2025 to a central estimate of 0.31 (95% range 0.00–0.70). A 5-year backtest shows a typical error of ±48.6%, 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 →
20260.300.000.69
20270.310.000.69
20280.310.000.70
20290.310.000.70
20300.310.000.70

Routes In Boreal Hardwood Transition

Routes recording Tennessee Warbler 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 →
ChisholmMINNESOTA152024
Sawbill CampMINNESOTA132025
GlendaleMINNESOTA102024
JordanMINNESOTA82025
MareniscoMICHIGAN52019
Isabella 2MICHIGAN52014
SidnawMICHIGAN52007
Imp LakeMICHIGAN42007
HovlandMINNESOTA42025
IsabellaMICHIGAN32009
Sand LakeMICHIGAN32000
LockportMINNESOTA32025
ShingletonMICHIGAN22023
MayfieldMICHIGAN22001
Sawbill LndgMINNESOTA22025
McgregorMINNESOTA22025
OntonagonMICHIGAN11971
BerglandMICHIGAN11990
BootjackMICHIGAN11994
HermanMICHIGAN12022
Crystal FlsMICHIGAN11992
Maple GroveMICHIGAN11997
Brocky LakeMICHIGAN12019
CunardMICHIGAN11997
CreightonMICHIGAN12009

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