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

Connecticut Warbler In Boreal Hardwood Transition

All regionsBoreal Hardwood TransitionForest birds

Connecticut Warbler in Boreal Hardwood Transition has edged down: down 25% on the route-weighted index since 1969.

-25%Since 1969TrendPercent 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 →
68Routes 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 →
57YearsYears 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 Connecticut Warbler in Boreal Hardwood Transition. See the full index history below.

Connecticut Warbler In Boreal Hardwood Transition Population Forecast

If the recent trend holds, Connecticut Warbler in Boreal Hardwood Transition is projected to rise about 217% by 2029 — from 0.05 in 2024 to a central estimate of 0.17 (95% range 0.00–0.53). A 5-year backtest shows a typical error of ±254.4%, with 100% of held-out values landing inside the 95% band.

+217%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 →
0.17Projected 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 →
0.00–0.5395% 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 →
±254.4%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, Connecticut Warbler in Boreal Hardwood Transition is projected to rise about 217% by 2029 — from 0.05 in 2024 to a central estimate of 0.17 (95% range 0.00–0.53). A 5-year backtest shows a typical error of ±254.4%, with 100% of held-out values landing inside the 95% band.19672029
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 →
20250.190.000.55
20260.180.000.54
20270.180.000.54
20280.170.000.53
20290.170.000.53

Routes In Boreal Hardwood Transition

Routes recording Connecticut 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 →
IsabellaMICHIGAN41989
WaskishMINNESOTA42019
Red LakeMINNESOTA42024
MontrealWISCONSIN31980
Gibbs CityMICHIGAN21985
CunardMICHIGAN22018
TahquamenonMICHIGAN21988
Skegemog PtMICHIGAN22000
FredericMICHIGAN21981
Mille LacsMINNESOTA21996
FloodwoodMINNESOTA22012
Crane LakeMINNESOTA22003
BlackduckMINNESOTA22004
GreenbushMINNESOTA22016
BayfieldWISCONSIN21983
ShanagoldenWISCONSIN21986
Popple RiverWISCONSIN21984
RhinelanderWISCONSIN21998
BerglandMICHIGAN11982
HermanMICHIGAN11984
Crystal FlsMICHIGAN11990
Maple GroveMICHIGAN12004
IshpemingMICHIGAN12021
ShingletonMICHIGAN11981
MuskallongeMICHIGAN12022

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