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

Nashville Warbler In Boreal Hardwood Transition

All regionsBoreal Hardwood TransitionForest birds

Nashville Warbler in Boreal Hardwood Transition has surged: up 173% on the route-weighted index since 1968.

+173%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 →
124Routes 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 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 →

Nashville Warbler has surged in Boreal Hardwood Transition: up 173% on the route-weighted index since 1968.

Nashville Warbler In Boreal Hardwood Transition Population Forecast

If the recent trend holds, Nashville Warbler in Boreal Hardwood Transition is projected to rise about 14% by 2030 — from 19 in 2025 to a central estimate of 21 (95% range 16–26). A 5-year backtest shows a typical error of ±14.8%, with 100% of held-out values landing inside the 95% band.

+14%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 →
21Projected 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 →
16–2695% 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 →
±14.8%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, Nashville Warbler in Boreal Hardwood Transition is projected to rise about 14% by 2030 — from 19 in 2025 to a central estimate of 21 (95% range 16–26). A 5-year backtest shows a typical error of ±14.8%, 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 →
2026201525
2027201526
2028211526
2029211626
2030211626

Routes In Boreal Hardwood Transition

Routes recording Nashville 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 →
JordanMINNESOTA1162025
Sherry LakeMINNESOTA1022022
Sawbill LndgMINNESOTA862025
ChisholmMINNESOTA722024
Brocky LakeMICHIGAN682025
Crane LakeMINNESOTA602025
GlendaleMINNESOTA542025
LockportMINNESOTA512025
Hart LakeMINNESOTA512025
IshpemingMICHIGAN492025
Betchler LksMICHIGAN482025
BlackduckMINNESOTA452022
Little ForkMINNESOTA432024
Gibbs CityMICHIGAN422025
Land O' Lakes 2WISCONSIN422025
BabbittMINNESOTA352025
Nett LakeMINNESOTA342024
MuskallongeMICHIGAN312024
Sawbill CampMINNESOTA312025
BigforkMINNESOTA302025
OntonagonMICHIGAN292019
SidnawMICHIGAN282025
CromwellMINNESOTA282025
HovlandMINNESOTA242025
CavourWISCONSIN242025

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