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

Chestnut-sided Warbler In Boreal Hardwood Transition

All regionsBoreal Hardwood TransitionForest birds

Chestnut-sided Warbler in Boreal Hardwood Transition has risen sharply: up 72% on the route-weighted index since 1968.

+72%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 →
124Routes 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 →

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 →

Chestnut-sided Warbler has risen sharply in Boreal Hardwood Transition: up 72% on the route-weighted index since 1968.

Chestnut-sided Warbler In Boreal Hardwood Transition Population Forecast

If the recent trend holds, Chestnut-sided Warbler in Boreal Hardwood Transition is projected to fall about 11% by 2030 — from 17 in 2025 to a central estimate of 16 (95% range 12–19). A 5-year backtest shows a typical error of ±19%, with 40% of held-out values landing inside the 95% band.

-11%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 →
16Projected 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 →
12–1995% 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 →
±19%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, Chestnut-sided Warbler in Boreal Hardwood Transition is projected to fall about 11% by 2030 — from 17 in 2025 to a central estimate of 16 (95% range 12–19). A 5-year backtest shows a typical error of ±19%, with 40% 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 →
2026151219
2027151219
2028151219
2029151219
2030161219

Routes In Boreal Hardwood Transition

Routes recording Chestnut-sided 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 →
Sherry LakeMINNESOTA642022
ChisholmMINNESOTA622024
Hart LakeMINNESOTA612025
Sawbill LndgMINNESOTA502025
Crane LakeMINNESOTA492025
LockportMINNESOTA462025
JordanMINNESOTA412025
GlendaleMINNESOTA382025
MinongWISCONSIN382025
AmbergWISCONSIN382025
Land O' Lakes 2WISCONSIN362025
BigforkMINNESOTA342025
BayfieldWISCONSIN332025
BlackduckMINNESOTA322022
McnaughtonWISCONSIN322024
MellenWISCONSIN322025
ShanagoldenWISCONSIN312025
Grand ViewWISCONSIN262025
BenaMINNESOTA251977
Cass LakeMINNESOTA242016
Popple RiverWISCONSIN242025
Amnicon FallsWISCONSIN242025
FlambeauWISCONSIN242025
Ned LakeMICHIGAN232025
CromwellMINNESOTA232025

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