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

Nashville Warbler Population Trend in New Hampshire

All statesForest birds

Nashville Warbler in New Hampshire has declined: down 45% on the route-weighted index since 1968.

-45%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 →
25Routes 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 Nashville 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 Nashville Warbler in New Hampshire. See the full index history below.

Nashville Warbler Population Forecast in New Hampshire

If the recent trend holds, Nashville Warbler in New Hampshire is projected to stay roughly flat through 2029, near 1.1 (95% range 0.04–2.1). A 5-year backtest shows a typical error of ±45.2%, with 100% of held-out values landing inside the 95% band.

+8%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 →
1.1Projected 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 →
0.04–2.195% 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 →
±45.2%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, Nashville Warbler in New Hampshire is projected to stay roughly flat through 2029, near 1.1 (95% range 0.04–2.1). A 5-year backtest shows a typical error of ±45.2%, 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 →
20251.20.132.2
20261.10.102.2
20271.10.082.2
20281.10.062.1
20291.10.042.1

Nashville Warbler Survey Routes in New Hampshire

Routes recording Nashville 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 →
Dixville Notch 21420242018
Dixvil Notch1020171966
Lempster220061972
Franconia220241966
Milan220241966
Clarksville220241968
Peterborough120171967
Brentwood119931966
Fitzwilliam120171966
Dover119961968
Hopkinton120131968
Epsom119991969
Concord120131970
Strafford120131968
Canterbury120101971
Gilmantn I W119881970
Wilmot120241966
Mt Chocorua120221969
Walpole120191966
Marlow120191967
Crawford Not119751966
Jefferson Hl120231966
Stratford120241966
Glen120181975
Jeffers Ntch120191993

Nashville Warbler Population Trend in Other States

californiaconnecticutidahomainemarylandmassachusettsmichiganminnesotamontananew-jerseynew-yorknorth-dakotaoregonpennsylvaniarhode-islandvermontvirginiawashingtonwest-virginiawisconsin

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