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

Black-and-white Warbler Population Trend in New Hampshire

All statesForest birds

Black-and-white Warbler in New Hampshire has held roughly steady: down 8% on the route-weighted index since 1968.

-8%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 Black-and-white 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 Black-and-white Warbler in New Hampshire. See the full index history below.

Black-and-white Warbler Population Forecast in New Hampshire

If the recent trend holds, Black-and-white Warbler in New Hampshire is projected to fall about 18% by 2030 — from 3.9 in 2025 to a central estimate of 3.2 (95% range 1.5–5.0). A 5-year backtest shows a typical error of ±9.4%, with 100% of held-out values landing inside the 95% band.

-18%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 →
3.2Projected 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 →
1.5–5.095% 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 →
±9.4%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, Black-and-white Warbler in New Hampshire is projected to fall about 18% by 2030 — from 3.9 in 2025 to a central estimate of 3.2 (95% range 1.5–5.0). A 5-year backtest shows a typical error of ±9.4%, 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 →
20263.41.75.1
20273.41.65.1
20283.31.65.0
20293.31.55.0
20303.21.55.0

Black-and-white Warbler Survey Routes in New Hampshire

Routes recording Black-and-white 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 →
Marlow1320251966
Fitzwilliam920251966
Walpole920251966
Lempster920251966
Canterbury720251966
Brentwood619981966
Wilmot620251966
Glen620251975
Mt Chocorua420251966
Stratford420251966
Hopkinton320251966
Epsom320251966
Jefferson Hl320251966
Milan320251966
Peterborough220231966
Concord220251966
Crawford Not219751966
Franconia220251966
Dixvil Notch220171968
Jeffers Ntch220251993
Dixville Notch 2220252018
Dover120251966
Strafford120241966
Gilmantn I W120251969
Clarksville120251966

Black-and-white Warbler Population Trend in Other States

alabamaarkansascaliforniaconnecticutdelawaregeorgiaillinoisindianakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourinebraskanew-jerseynew-yorknorth-carolinanorth-dakotaohiooklahomapennsylvaniarhode-islandsouth-carolinatennesseetexasvermontvirginiawest-virginiawisconsinwyoming

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