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

Black-throated Blue Warbler Population Trend in New Hampshire

All statesForest birds

Black-throated Blue Warbler in New Hampshire has surged: up 231% on the route-weighted index since 1968.

+231%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 Blue 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 Blue Warbler has surged in New Hampshire: up 231% on the route-weighted index since 1968.

Black-throated Blue Warbler Population Forecast in New Hampshire

If the recent trend holds, Black-throated Blue Warbler in New Hampshire is projected to rise about 81% by 2029 — from 1.9 in 2024 to a central estimate of 3.4 (95% range 2.2–4.5). A 5-year backtest shows a typical error of ±82.8%, with 20% of held-out values landing inside the 95% band.

+81%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 →
3.4Projected 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 →
2.2–4.595% 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 →
±82.8%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 Blue Warbler in New Hampshire is projected to rise about 81% by 2029 — from 1.9 in 2024 to a central estimate of 3.4 (95% range 2.2–4.5). A 5-year backtest shows a typical error of ±82.8%, 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 →
20253.22.14.3
20263.22.14.4
20273.32.24.4
20283.32.24.5
20293.42.24.5

Black-throated Blue Warbler Survey Routes in New Hampshire

Routes recording Black-throated Blue 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 →
Wilmot720241968
Mt Chocorua720241967
Stratford620231966
Lempster420241981
Jeffers Ntch320241993
Dixville Notch 2320242018
Concord220241992
Gilmantn I W220241969
Marlow220241968
Milan220241971
Clarksville220241967
Peterborough120181969
Brentwood119841984
Fitzwilliam120241966
Dover119731973
Hopkinton120241967
Epsom120171966
Strafford120221966
Canterbury120241970
Walpole120241969
Crawford Not119751967
Jefferson Hl120241966
Franconia120241966
Dixvil Notch120171966
Glen120241975

Black-throated Blue Warbler Population Trend in Other States

connecticutgeorgiamainemarylandmassachusettsmichiganminnesotanew-jerseynew-yorknorth-carolinapennsylvaniarhode-islandtennesseevermontvirginiawest-virginiawisconsin

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