BirdAnalyst
Species · Maine · BBS 2026 Release · 1966–2025

Chestnut-sided Warbler Population Trend in Maine

All statesForest birds

Chestnut-sided Warbler in Maine has edged up: up 13% on the route-weighted index since 1968.

+13%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 →
77Routes In StateSurvey 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 Chestnut-sided Warbler Trends in MaineNotable 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 Chestnut-sided Warbler in Maine. See the full index history below.

Chestnut-sided Warbler Population Forecast in Maine

If the recent trend holds, Chestnut-sided Warbler in Maine is projected to fall about 25% by 2030 — from 7.4 in 2025 to a central estimate of 5.6 (95% range 1.7–9.5). A 5-year backtest shows a typical error of ±21.5%, with 100% of held-out values landing inside the 95% band.

-25%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 →
5.6Projected 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 →
1.7–9.595% 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 →
±21.5%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 Maine is projected to fall about 25% by 2030 — from 7.4 in 2025 to a central estimate of 5.6 (95% range 1.7–9.5). A 5-year backtest shows a typical error of ±21.5%, 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 →
20265.92.09.7
20275.81.99.7
20285.71.89.6
20295.71.89.5
20305.61.79.5

Chestnut-sided Warbler Survey Routes in Maine

Routes recording Chestnut-sided Warbler in Maine.
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 →
East Troy3720211972
Hermon2220211966
Cornville2020252012
Harmony1920251968
Searsport1820252002
Brooks1720211977
Castine1720061976
Hudson1620161973
Benton1419801971
Washburn1420051979
Hartford1320251975
Bowdoin Ctr1320211972
Northfield1219811976
Moose River1220081983
Wytopitlock1220251976
Otisfield Gr1120151971
Warren1119901973
Forest Sta1120001966
Manchester1019951971
Ft Fairfield1020051993
Benedicta920221976
St David920051982
Turner 2920252011
Reeds820251990
Cooper820211975

Chestnut-sided Warbler Population Trend in Other States

alabamaarkansascoloradoconnecticutgeorgiaillinoisindianaiowakansaskentuckymarylandmassachusettsmichiganminnesotanevadanew-hampshirenew-jerseynew-yorknorth-carolinanorth-dakotaohiopennsylvaniarhode-islandtennesseevermontvirginiawest-virginiawisconsinwyoming

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