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

Blue-winged Warbler In Boreal Hardwood Transition

All regionsBoreal Hardwood TransitionForest birds

Blue-winged Warbler in Boreal Hardwood Transition has edged down: down 18% on the route-weighted index since 1980.

-18%Since 1980TrendPercent 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 →
24Routes 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 →
28YearsYears 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 →

No notable trend signals for Blue-winged Warbler in Boreal Hardwood Transition. See the full index history below.

Blue-winged Warbler In Boreal Hardwood Transition Population Forecast

If the recent trend holds, Blue-winged Warbler in Boreal Hardwood Transition is projected to stay roughly flat through 2029, near 0.03 (95% range 0.00–0.07). A 5-year backtest shows a typical error of ±49.6%, with 100% of held-out values landing inside the 95% band.

n/aChange 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 →
0.03Projected 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 →
0.00–0.0795% 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 →
±49.6%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, Blue-winged Warbler in Boreal Hardwood Transition is projected to stay roughly flat through 2029, near 0.03 (95% range 0.00–0.07). A 5-year backtest shows a typical error of ±49.6%, with 100% of held-out values landing inside the 95% band.19732029
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 →
20250.030.000.07
20260.030.000.07
20270.030.000.07
20280.030.000.07
20290.030.000.07

Routes In Boreal Hardwood Transition

Routes recording Blue-winged 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 →
DebsMINNESOTA32017
Walloon LakeMICHIGAN21980
IrmaWISCONSIN22022
AmbergWISCONSIN22018
Weirgor SpringsWISCONSIN22024
MareniscoMICHIGAN12005
CunardMICHIGAN12021
Bear LakeMICHIGAN12024
Lake CityMICHIGAN11974
SkeelsMICHIGAN12011
OberlinMICHIGAN12006
CathroMICHIGAN12011
Sand LakeMICHIGAN12014
HarriettaMICHIGAN12005
BlackduckMINNESOTA12005
Nett LakeMINNESOTA12018
Tamarac NwrMINNESOTA11998
Grand ViewWISCONSIN12011
Union TwpWISCONSIN11992
CouderayWISCONSIN11996
ExelandWISCONSIN12005
HollisterWISCONSIN11973
Washington IWISCONSIN11973
BashawWISCONSIN12021

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