BirdAnalyst
Species · New Hampshire · BBS 2026 Release · 1966–2025

Chestnut-sided Warbler Population Trend in New Hampshire

All statesForest birds

Chestnut-sided Warbler in New Hampshire has held roughly steady: up 1% on the route-weighted index since 1968.

+1%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 →
26Routes 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 New HampshireNotable 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 New Hampshire. See the full index history below.

Chestnut-sided Warbler Population Forecast in New Hampshire

If the recent trend holds, Chestnut-sided Warbler in New Hampshire is projected to fall about 30% by 2030 — from 10 in 2025 to a central estimate of 7.3 (95% range 2.8–12). A 5-year backtest shows a typical error of ±35.6%, with 100% of held-out values landing inside the 95% band.

-30%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 →
7.3Projected 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 →
2.8–1295% 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 →
±35.6%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 New Hampshire is projected to fall about 30% by 2030 — from 10 in 2025 to a central estimate of 7.3 (95% range 2.8–12). A 5-year backtest shows a typical error of ±35.6%, 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 →
20267.63.112
20277.53.112
20287.53.012
20297.42.912
20307.32.812

Chestnut-sided Warbler Survey Routes in New Hampshire

Routes recording Chestnut-sided Warbler in New Hampshire.
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 →
Lempster2220251966
Glen2120251975
Walpole1920251966
Jefferson Hl1720251966
Clarksville1620251969
Stratford1420251966
Milan1320251966
Fitzwilliam1220251966
Canterbury1220251966
Wilmot1220251966
Dixville Notch 21220252018
Marlow1120251966
Mt Chocorua1020251966
Dixvil Notch1020171966
Crawford Not919751966
Concord820251966
Gilmantn I W820251969
Hopkinton720251966
Franconia720251966
Dover520251966
Jeffers Ntch520251993
Strafford320251966
Peterborough220251966
Brentwood219981966
Epsom120251966

Chestnut-sided Warbler Population Trend in Other States

alabamaarkansascoloradoconnecticutgeorgiaillinoisindianaiowakansaskentuckymainemarylandmassachusettsmichiganminnesotanevadanew-jerseynew-yorknorth-carolinanorth-dakotaohiopennsylvaniarhode-islandtennesseevermontvirginiawest-virginiawisconsinwyoming

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