BirdAnalyst
Species · Maine · BBS 2025 Release · 1966–2024

Chestnut-sided Warbler Population Trend in Maine

All statesForest birds

Chestnut-sided Warbler in Maine has held roughly steady: up 9% on the route-weighted index since 1968.

+9%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 →
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 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 18% by 2029 — from 6.6 in 2024 to a central estimate of 5.4 (95% range 1.6–9.3). A 5-year backtest shows a typical error of ±18.2%, with 100% of held-out values landing inside the 95% band.

-18%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 →
5.4Projected 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 →
1.6–9.395% 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 →
±18.2%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 18% by 2029 — from 6.6 in 2024 to a central estimate of 5.4 (95% range 1.6–9.3). A 5-year backtest shows a typical error of ±18.2%, 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 →
20255.71.89.5
20265.61.89.5
20275.51.79.4
20285.51.69.3
20295.41.69.3

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 Troy2220191972
Cornville2020242012
Brooks1720191977
Castine1720061976
Hudson1620161973
Hartford1520241975
Hermon1520191966
Benton1419801971
Washburn1420051979
Bowdoin Ctr1320211972
Northfield1219811976
Moose River1220081983
Turner 21220242011
Searsport1220242002
Otisfield Gr1120151971
Warren1119901973
Forest Sta1120001966
Manchester1019951971
Harmony1020241968
Charleston1020191975
Ft Fairfield1020051993
Benedicta920221976
St David920051982
Reeds820241990
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 2026-05-22.