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

Blackpoll Warbler Population Trend in New Hampshire

All statesForest birds

Blackpoll Warbler in New Hampshire has fallen sharply: down 70% on the route-weighted index since 1970.

-70%Since 1970TrendPercent 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 →
11Routes 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 →
33YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Blackpoll 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 declinecomputed 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 →

Blackpoll Warbler has fallen sharply in New Hampshire: down 70% on the route-weighted index since 1970.

Blackpoll Warbler Population Forecast in New Hampshire

If the recent trend holds, Blackpoll Warbler in New Hampshire is projected to stay roughly flat through 2016, near 0.04 (95% range 0.00–0.19). A 5-year backtest shows a typical error of ±33.7%, with 100% of held-out values landing inside the 95% band.

n/aChange by 2016TrendPercent 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 →
0.04Projected 2016 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–0.1995% 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 →
±33.7%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, Blackpoll Warbler in New Hampshire is projected to stay roughly flat through 2016, near 0.04 (95% range 0.00–0.19). A 5-year backtest shows a typical error of ±33.7%, with 100% of held-out values landing inside the 95% band.19682016
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 →
20120.050.000.20
20130.050.000.20
20140.050.000.20
20150.040.000.20
20160.040.000.19

Blackpoll Warbler Survey Routes in New Hampshire

Routes recording Blackpoll 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 →
Crawford Not519731968
Clarksville220091968
Fitzwilliam119821970
Hopkinton119691969
Mt Chocorua119931976
Jefferson Hl119711968
Franconia119891972
Milan119751975
Jeffers Ntch120111994
Dixvil Notch120001975
Glen119831983

Blackpoll Warbler Population Trend in Other States

alaskamainemassachusettsnew-yorkpennsylvaniavermont

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