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

Black-throated Green Warbler Population Trend in New Hampshire

All statesForest birds

Black-throated Green Warbler in New Hampshire has surged: up 159% on the route-weighted index since 1968.

+159%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-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 158% 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 64% by 2029 — from 3.4 in 2024 to a central estimate of 5.5 (95% range 2.9–8.1). A 5-year backtest shows a typical error of ±99.5%, with 20% of held-out values landing inside the 95% band.

+64%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 →
5.5Projected 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 →
2.9–8.195% 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 →
±99.5%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 64% by 2029 — from 3.4 in 2024 to a central estimate of 5.5 (95% range 2.9–8.1). A 5-year backtest shows a typical error of ±99.5%, with 20% 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 →
20255.22.77.8
20265.32.77.9
20275.42.87.9
20285.42.98.0
20295.52.98.1

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 21320242018
Clarksville1120241969
Walpole720241967
Jeffers Ntch620241993
Canterbury520241966
Wilmot520241969
Franconia520241966
Fitzwilliam420241966
Mt Chocorua420241966
Jefferson Hl420241966
Lempster320241972
Peterborough220241968
Brentwood219961968
Hopkinton220231966
Stratford220211971
Glen220241975
East Kingston220172000
Dover120211966
Epsom120231969
Concord120191967
Strafford120241966
Gilmantn I W120241969
Marlow120241966
Crawford Not119751967

Black-throated Green Warbler Population Trend in Other States

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

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