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

Mourning Warbler In Boreal Hardwood Transition

All regionsBoreal Hardwood TransitionForest birds

Mourning Warbler in Boreal Hardwood Transition has increased: up 48% on the route-weighted index since 1968.

+48%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 →
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 →

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

Forecast

If the recent trend holds, Mourning Warbler in Boreal Hardwood Transition is projected to stay roughly flat through 2029, near 6.1 (95% range 3.9–8.4). A 5-year backtest shows a typical error of ±4.9%, 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 →
6.1Projected 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 →
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 →
±4.9%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 2029, near 6.1 (95% range 3.9–8.4). A 5-year backtest shows a typical error of ±4.9%, with 100% 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 →
20256.23.98.4
20266.23.98.4
20276.23.98.4
20286.23.98.4
20296.13.98.4

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 LakeMINNESOTA352024
LockportMINNESOTA312024
Crane LakeMINNESOTA242024
GlendaleMINNESOTA242024
HovlandMINNESOTA222024
Sherry LakeMINNESOTA202022
ChisholmMINNESOTA172024
JordanMINNESOTA152023
BayfieldWISCONSIN152024
MellenWISCONSIN152024
Ned LakeMICHIGAN132024
MontrealWISCONSIN132024
Popple RiverWISCONSIN122024
ShingletonMICHIGAN112024
CromwellMINNESOTA112024
FloodwoodMINNESOTA102024
CavourWISCONSIN102024
RacoMICHIGAN92024
FredericMICHIGAN92001
Little ForkMINNESOTA92024
Amnicon FallsWISCONSIN92024
Gibbs CityMICHIGAN82024
Sawbill CampMINNESOTA82024
HollisterWISCONSIN82024
OntonagonMICHIGAN72019

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