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

Blackburnian Warbler Population Trend in New Hampshire

All statesForest birds

Blackburnian Warbler in New Hampshire has surged: up 168% on the route-weighted index since 1968.

+168%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 →
25Routes 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 Blackburnian 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 →

Blackburnian Warbler has surged in New Hampshire: up 168% on the route-weighted index since 1968.

Blackburnian Warbler Population Forecast in New Hampshire

If the recent trend holds, Blackburnian Warbler in New Hampshire is projected to rise about 30% by 2029 — from 2.8 in 2024 to a central estimate of 3.6 (95% range 2.7–4.5). A 5-year backtest shows a typical error of ±24.4%, with 80% of held-out values landing inside the 95% band.

+30%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 →
3.6Projected 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 →
2.7–4.595% 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 →
±24.4%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, Blackburnian Warbler in New Hampshire is projected to rise about 30% by 2029 — from 2.8 in 2024 to a central estimate of 3.6 (95% range 2.7–4.5). A 5-year backtest shows a typical error of ±24.4%, with 80% 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 →
20253.42.54.4
20263.52.54.4
20273.52.64.5
20283.62.64.5
20293.62.74.5

Blackburnian Warbler Survey Routes in New Hampshire

Routes recording Blackburnian 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 →
Dixville Notch 21220242018
Clarksville1020241966
Dixvil Notch920171966
Franconia820241966
Glen720241975
Walpole520241966
Wilmot320241970
Mt Chocorua320241967
Peterborough220241967
Epsom220181972
Lempster220241972
Jefferson Hl220241966
Brentwood119861973
Fitzwilliam120241966
Dover119861969
Hopkinton120221966
Concord120211967
Strafford120241969
Canterbury120241966
Gilmantn I W120111970
Marlow120241974
Crawford Not119741968
Milan120241966
Stratford120241966
Jeffers Ntch120241993

Blackburnian Warbler Population Trend in Other States

connecticutgeorgiaindianamainemarylandmassachusettsmichiganminnesotanew-jerseynew-yorknorth-carolinaohiopennsylvaniarhode-islandtennesseevermontvirginiawest-virginiawisconsin

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