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

Black-and-white Warbler Population Trend in New Hampshire

All statesForest birds

Black-and-white Warbler in New Hampshire has held roughly steady: down 7% on the route-weighted index since 1968.

-7%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 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 stay roughly flat through 2029, near 3.2 (95% range 1.5–5.0). A 5-year backtest shows a typical error of ±6.9%, with 100% of held-out values landing inside the 95% band.

-5%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 →
3.2Projected 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 →
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 →
±6.9%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 stay roughly flat through 2029, near 3.2 (95% range 1.5–5.0). A 5-year backtest shows a typical error of ±6.9%, 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 →
20253.41.75.2
20263.41.65.1
20273.31.65.1
20283.31.55.0
20293.21.55.0

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 →
Lempster1620241966
Fitzwilliam920241966
Canterbury720241966
Brentwood619981966
Glen620241975
Dixville Notch 2620242018
Hopkinton520241966
Walpole520241966
Marlow420241966
Jefferson Hl420241966
Epsom320231966
Concord320241966
Wilmot320241966
Milan320241966
Peterborough220231966
Dover220231966
Gilmantn I W220241969
Crawford Not219751966
Dixvil Notch220171968
Strafford120241966
Mt Chocorua120231966
Franconia120241966
Stratford120231966
Clarksville120221966
East Kingston120221999

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 2026-05-22.