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

Black-throated Green Warbler Population Trend in New Hampshire

All statesForest birds

Black-throated Green Warbler in New Hampshire has surged: up 131% on the route-weighted index since 1968.

+131%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-throated Green 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 →

long arc increasecomputed indexTrend sourceWhether the figure is our own computed route-weighted index or an official USGS modeled estimate. The current build labels every trend as computed.Full methodology →

Black-throated Green Warbler has surged in New Hampshire: up 131% on the route-weighted index since 1968.

Black-throated Green Warbler Population Forecast in New Hampshire

If the recent trend holds, Black-throated Green Warbler in New Hampshire is projected to rise about 87% by 2030 — from 2.9 in 2025 to a central estimate of 5.4 (95% range 2.8–8.0). A 5-year backtest shows a typical error of ±87.7%, with 20% of held-out values landing inside the 95% band.

+87%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 →
5.4Projected 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 →
2.8–8.095% 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 →
±87.7%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-throated Green Warbler in New Hampshire is projected to rise about 87% by 2030 — from 2.9 in 2025 to a central estimate of 5.4 (95% range 2.8–8.0). A 5-year backtest shows a typical error of ±87.7%, with 20% 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 →
20265.12.57.7
20275.22.67.8
20285.22.67.9
20295.32.77.9
20305.42.88.0

Black-throated Green Warbler Survey Routes in New Hampshire

Routes recording Black-throated Green 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 →
Dixvil Notch1520171966
Dixville Notch 21520252018
Walpole1020251967
Clarksville920251969
Canterbury720251966
Fitzwilliam520251966
Franconia520251966
Wilmot420251969
Lempster320251972
Jeffers Ntch320251993
Peterborough220241968
Brentwood219961968
Hopkinton220231966
Stratford220211971
Glen220241975
East Kingston220172000
Dover120211966
Epsom120231969
Concord120251967
Strafford120241966
Gilmantn I W120251969
Mt Chocorua120251966
Marlow120251966
Crawford Not119751967
Jefferson Hl120251966

Black-throated Green Warbler Population Trend in Other States

alabamaarkansasconnecticutgeorgiaindianakentuckymainemarylandmassachusettsmichiganminnesotamissourinew-jerseynew-yorknorth-carolinaohiooklahomapennsylvaniarhode-islandsouth-carolinatennesseevermontvirginiawest-virginiawisconsin

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