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

Willow Flycatcher Population Trend in New Hampshire

All statesAerial insectivores

Willow Flycatcher in New Hampshire has surged: up 205% on the route-weighted index since 1975.

+205%Since 1975TrendPercent 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 →
21Routes 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 →
49YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Willow Flycatcher 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 →

Willow Flycatcher has surged in New Hampshire: up 205% on the route-weighted index since 1975.

Willow Flycatcher Population Forecast in New Hampshire

If the recent trend holds, Willow Flycatcher in New Hampshire is projected to fall about 14% by 2029 — from 0.27 in 2024 to a central estimate of 0.24 (95% range 0.06–0.41). A 5-year backtest shows a typical error of ±34.6%, with 60% of held-out values landing inside the 95% band.

-14%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 →
0.24Projected 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 →
0.06–0.4195% 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 →
±34.6%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, Willow Flycatcher in New Hampshire is projected to fall about 14% by 2029 — from 0.27 in 2024 to a central estimate of 0.24 (95% range 0.06–0.41). A 5-year backtest shows a typical error of ±34.6%, with 60% of held-out values landing inside the 95% band.19732029
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 →
20250.230.050.40
20260.230.050.40
20270.230.060.41
20280.230.060.41
20290.240.060.41

Willow Flycatcher Survey Routes in New Hampshire

Routes recording Willow Flycatcher 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 →
Dover420231985
Wilmot220191984
Jefferson Hl220241999
Stratford220022002
East Kingston220191999
Peterborough120241974
Brentwood119961975
Fitzwilliam120231983
Hopkinton120221976
Epsom119991999
Concord120242008
Strafford119971997
Canterbury120241983
Walpole120121975
Marlow120241976
Lempster120192019
Franconia119821973
Milan120221976
Dixvil Notch119861986
Glen119961996
Jeffers Ntch120182018

Willow Flycatcher Population Trend in Other States

alaskaarizonaarkansascaliforniacoloradoconnecticutdelawaregeorgiaidahoillinoisindianaiowakansaskentuckymainemarylandmassachusettsmichiganminnesotamissourimontananebraskanevadanew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniarhode-islandsouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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