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

Mourning Warbler In Boreal Hardwood Transition

All regionsBoreal Hardwood TransitionForest birds

Mourning Warbler in Boreal Hardwood Transition has increased: up 50% on the route-weighted index since 1968.

+50%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 →
122Routes 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 →

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

Mourning Warbler In Boreal Hardwood Transition Population Forecast

If the recent trend holds, Mourning Warbler in Boreal Hardwood Transition is projected to stay roughly flat through 2030, near 6.2 (95% range 3.9–8.4). A 5-year backtest shows a typical error of ±3.9%, with 100% of held-out values landing inside the 95% band.

-7%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 →
6.2Projected 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 →
3.9–8.495% 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 →
±3.9%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, Mourning Warbler in Boreal Hardwood Transition is projected to stay roughly flat through 2030, near 6.2 (95% range 3.9–8.4). A 5-year backtest shows a typical error of ±3.9%, with 100% 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 →
20266.24.08.4
20276.24.08.4
20286.24.08.4
20296.23.98.4
20306.23.98.4

Routes In Boreal Hardwood Transition

Routes recording Mourning 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 →
Hart LakeMINNESOTA472025
LockportMINNESOTA362025
JordanMINNESOTA232025
Sherry LakeMINNESOTA202022
GlendaleMINNESOTA202025
Sawbill LndgMINNESOTA192025
ShanagoldenWISCONSIN192025
Ned LakeMICHIGAN182025
HovlandMINNESOTA182025
ChisholmMINNESOTA172024
FloodwoodMINNESOTA162025
Crane LakeMINNESOTA162025
PickfordMICHIGAN152025
CromwellMINNESOTA152025
MellenWISCONSIN152025
BayfieldWISCONSIN132025
Popple RiverWISCONSIN132025
CavourWISCONSIN132025
BigforkMINNESOTA122025
HollisterWISCONSIN112025
Brocky LakeMICHIGAN102025
BabbittMINNESOTA102025
Grand ViewWISCONSIN102025
FredericMICHIGAN92001
Little ForkMINNESOTA92024

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