BirdAnalyst
Species · New Hampshire · BBS 2025 Release · 1966–2024

Chestnut-sided Warbler Population Trend in New Hampshire

All statesForest birds

Chestnut-sided Warbler in New Hampshire has held roughly steady: up 4% on the route-weighted index since 1968.

+4%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 →
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 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 34% by 2029 — from 11 in 2024 to a central estimate of 7.2 (95% range 2.7–12). A 5-year backtest shows a typical error of ±31.4%, with 80% of held-out values landing inside the 95% band.

-34%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 →
7.2Projected 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 →
2.7–1295% 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 →
±31.4%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 34% by 2029 — from 11 in 2024 to a central estimate of 7.2 (95% range 2.7–12). A 5-year backtest shows a typical error of ±31.4%, with 80% 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 →
20257.63.112
20267.53.012
20277.42.912
20287.32.812
20297.22.712

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 →
Lempster2520241966
Glen2420241975
Jefferson Hl2120241966
Stratford2120241966
Canterbury1620241966
Gilmantn I W1420241969
Walpole1420241966
Wilmot1220241966
Milan1220241966
Dixville Notch 21220242018
Clarksville1120241969
Fitzwilliam1020241966
Marlow1020241966
Dixvil Notch1020171966
Crawford Not919751966
Hopkinton820241966
Concord720241966
Strafford520241966
Mt Chocorua520241966
East Kingston420241999
Jeffers Ntch420241993
Franconia320241966
Brentwood219981966
Dover220241966
Epsom220221966

Chestnut-sided Warbler Population Trend in Other States

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

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