BirdAnalyst
Species · BCR 12 · BBS 2025 Release · 1966–2024

Black-throated Green Warbler In Boreal Hardwood Transition

All regionsBoreal Hardwood TransitionForest birds

Black-throated Green Warbler in Boreal Hardwood Transition has surged: up 110% on the route-weighted index since 1968.

+110%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 →
58YearsYears 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 110% 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 44% by 2029 — from 5.2 in 2024 to a central estimate of 7.5 (95% range 5.8–9.2). A 5-year backtest shows a typical error of ±27.9%, with 60% of held-out values landing inside the 95% band.

+44%Change 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 →
7.5Projected 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 →
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 →
±27.9%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 44% by 2029 — from 5.2 in 2024 to a central estimate of 7.5 (95% range 5.8–9.2). A 5-year backtest shows a typical error of ±27.9%, with 60% of held-out values landing inside the 95% band.19662029
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 →
20257.25.58.9
20267.35.69.0
20277.45.79.0
20287.45.89.1
20297.55.89.2

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 IWISCONSIN402024
HovlandMINNESOTA312024
BlackduckMINNESOTA302022
Eagle RiverWISCONSIN282024
Imp LakeMICHIGAN242019
Land O LakesWISCONSIN242016
LockportMINNESOTA232024
EnsignMICHIGAN222010
Scott'S MarshMICHIGAN162010
Big Island LakeMICHIGAN162010
Land O' Lakes 2WISCONSIN162024
Hiawatha NfMICHIGAN152024
SidnawMICHIGAN152024
MareniscoMICHIGAN142019
GooseneckMICHIGAN142010
CavourWISCONSIN142024
MellenWISCONSIN132024
GilchristMICHIGAN122021
Isabella 2MICHIGAN122024
Cluster LakesMICHIGAN122010
McnaughtonWISCONSIN122024
BigforkMINNESOTA112024
ChisholmMINNESOTA112024
ShanagoldenWISCONSIN112024
OntonagonMICHIGAN102019

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