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

Kirtland's Warbler In Boreal Hardwood Transition

All regionsBoreal Hardwood TransitionForest birds

Kirtland's Warbler in Boreal Hardwood Transition has surged: up 169% on the route-weighted index since 2000.

+169%Since 2000TrendPercent 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 →
11Routes 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 →
26YearsYears 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 →

Kirtland's Warbler has surged in Boreal Hardwood Transition: up 169% on the route-weighted index since 2000.

Kirtland's Warbler In Boreal Hardwood Transition Population Forecast

If the recent trend holds, Kirtland's Warbler in Boreal Hardwood Transition is projected to stay roughly flat through 2029, near 0.10 (95% range 0.04–0.15). A 5-year backtest shows a typical error of ±55.7%, with 100% of held-out values landing inside the 95% band.

+5%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 →
0.10Projected 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 →
0.04–0.1595% 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 →
±55.7%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, Kirtland's Warbler in Boreal Hardwood Transition is projected to stay roughly flat through 2029, near 0.10 (95% range 0.04–0.15). A 5-year backtest shows a typical error of ±55.7%, with 100% of held-out values landing inside the 95% band.19862029
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 →
20250.090.040.14
20260.090.040.15
20270.090.040.15
20280.100.040.15
20290.100.040.15

Routes In Boreal Hardwood Transition

Routes recording Kirtland's 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 →
Sand LakeMICHIGAN72024
Red OakMICHIGAN52022
SkeelsMICHIGAN32011
AmbergWISCONSIN22012
IshpemingMICHIGAN12010
Skegemog PtMICHIGAN12013
MayfieldMICHIGAN12014
Hiawatha NfMICHIGAN12013
Betchler LksMICHIGAN12016
Scott'S MarshMICHIGAN12008
Big Island LakeMICHIGAN12009

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