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

Black-throated Green Warbler In Boreal Hardwood Transition

All regionsBoreal Hardwood TransitionForest birds

Black-throated Green Warbler in Boreal Hardwood Transition has surged: up 103% on the route-weighted index since 1968.

+103%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 →
117Routes 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 →

Black-throated Green Warbler has surged in Boreal Hardwood Transition: up 103% on the route-weighted index since 1968.

Black-throated Green Warbler In Boreal Hardwood Transition Population Forecast

If the recent trend holds, Black-throated Green Warbler in Boreal Hardwood Transition is projected to rise about 38% by 2030 — from 5.4 in 2025 to a central estimate of 7.5 (95% range 5.8–9.2). A 5-year backtest shows a typical error of ±32.5%, with 40% of held-out values landing inside the 95% band.

+38%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 →
7.5Projected 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 →
5.8–9.295% 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 →
±32.5%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, Black-throated Green Warbler in Boreal Hardwood Transition is projected to rise about 38% by 2030 — from 5.4 in 2025 to a central estimate of 7.5 (95% range 5.8–9.2). A 5-year backtest shows a typical error of ±32.5%, with 40% 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 →
20267.15.48.9
20277.25.59.0
20287.35.69.0
20297.45.79.1
20307.55.89.2

Routes In Boreal Hardwood Transition

Routes recording Black-throated Green 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 →
Washington IWISCONSIN412025
LockportMINNESOTA362025
BlackduckMINNESOTA302022
HovlandMINNESOTA252025
Imp LakeMICHIGAN242019
Land O LakesWISCONSIN242016
EnsignMICHIGAN222010
RacoMICHIGAN202025
Eagle RiverWISCONSIN182025
Sawbill CampMINNESOTA172025
TahquamenonMICHIGAN162025
Scott'S MarshMICHIGAN162010
Big Island LakeMICHIGAN162010
MellenWISCONSIN152025
MareniscoMICHIGAN142019
GooseneckMICHIGAN142010
Hiawatha NfMICHIGAN132025
GilchristMICHIGAN122021
Cluster LakesMICHIGAN122010
McnaughtonWISCONSIN122024
Land O' Lakes 2WISCONSIN122025
JordanMINNESOTA112025
ChisholmMINNESOTA112024
OntonagonMICHIGAN102019
MuskallongeMICHIGAN102024

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