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

Prairie Warbler Population Trend in New Hampshire

All statesForest birds

Prairie Warbler in New Hampshire has surged: up 201% on the route-weighted index since 1968.

+201%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 →
14Routes 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 →
56YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Prairie 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 →

Prairie Warbler has surged in New Hampshire: up 201% on the route-weighted index since 1968.

Prairie Warbler Population Forecast in New Hampshire

If the recent trend holds, Prairie Warbler in New Hampshire is projected to stay roughly flat through 2029, near 0.49 (95% range 0.17–0.82). A 5-year backtest shows a typical error of ±48.7%, with 40% of held-out values landing inside the 95% band.

-1%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 →
0.49Projected 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 →
0.17–0.8295% 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 →
±48.7%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, Prairie Warbler in New Hampshire is projected to stay roughly flat through 2029, near 0.49 (95% range 0.17–0.82). A 5-year backtest shows a typical error of ±48.7%, with 40% 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 →
20250.470.140.79
20260.470.150.80
20270.480.160.80
20280.490.160.81
20290.490.170.82

Prairie Warbler Survey Routes in New Hampshire

Routes recording Prairie 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 →
Concord420241967
Hopkinton320221966
Epsom320221969
Fitzwilliam220241992
Canterbury220241969
Gilmantn I W220182018
Marlow220242014
Jefferson Hl220002000
Peterborough120131972
Brentwood119921968
Dover120241966
Strafford120231970
Wilmot120211974
Walpole120212021

Prairie Warbler Population Trend in Other States

alabamaarkansascaliforniaconnecticutdelawarefloridageorgiaillinoisindianakentuckylouisianamainemarylandmassachusettsmichiganmississippimissourinew-jerseynew-yorknorth-carolinaohiooklahomapennsylvaniarhode-islandsouth-carolinatennesseetexasvermontvirginiawest-virginiawisconsin

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