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

Wilson's Warbler Population Trend in New Hampshire

All statesForest birds

Wilson's Warbler in New Hampshire has fallen sharply: down 68% on the route-weighted index since 1968.

-68%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 →
8Routes 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 →
20YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Wilson's 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 →

Wilson's Warbler has fallen sharply in New Hampshire: down 68% on the route-weighted index since 1968.

Wilson's Warbler Population Forecast in New Hampshire

If the recent trend holds, Wilson's Warbler in New Hampshire is projected to fall about 99% by 2020 — from 0.09 in 2015 to a central estimate of 0.00 (95% range 0.00–0.34). A 5-year backtest shows a typical error of ±181.3%, with 100% of held-out values landing inside the 95% band.

-99%Change by 2020TrendPercent 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 →
0.00Projected 2020 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–0.3495% 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 →
±181.3%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, Wilson's Warbler in New Hampshire is projected to fall about 99% by 2020 — from 0.09 in 2015 to a central estimate of 0.00 (95% range 0.00–0.34). A 5-year backtest shows a typical error of ±181.3%, with 100% of held-out values landing inside the 95% band.19662020
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 →
20160.020.000.35
20170.010.000.35
20180.010.000.35
20190.010.000.34
20200.000.000.34

Wilson's Warbler Survey Routes in New Hampshire

Routes recording Wilson's 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 →
Mt Chocorua619751975
Franconia619751966
Jefferson Hl519661966
Milan220151966
Stratford119801966
Dixvil Notch119771966
Clarksville120071968
Glen119761976

Wilson's Warbler Population Trend in Other States

alaskacaliforniacoloradoidahomainemichiganminnesotamontananevadanew-mexiconew-yorkoregonutahvermontwashingtonwisconsinwyoming

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