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Species · New Hampshire · BBS 2026 Release · 1966–2025

Louisiana Waterthrush Population Trend in New Hampshire

All statesForest birds

Louisiana Waterthrush in New Hampshire has surged: up 321% on the route-weighted index since 1968.

+321%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 →
18Routes 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 →
53YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Louisiana Waterthrush 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 →

Louisiana Waterthrush has surged in New Hampshire: up 321% on the route-weighted index since 1968.

Louisiana Waterthrush Population Forecast in New Hampshire

If the recent trend holds, Louisiana Waterthrush in New Hampshire is projected to fall about 58% by 2030 — from 0.65 in 2025 to a central estimate of 0.27 (95% range 0.05–0.50). A 5-year backtest shows a typical error of ±53%, with 40% of held-out values landing inside the 95% band.

-58%Change by 2030TrendPercent 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 →
0.27Projected 2030 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.05–0.5095% 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 →
±53%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, Louisiana Waterthrush in New Hampshire is projected to fall about 58% by 2030 — from 0.65 in 2025 to a central estimate of 0.27 (95% range 0.05–0.50). A 5-year backtest shows a typical error of ±53%, with 40% of held-out values landing inside the 95% band.19662030
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 →
20260.260.030.48
20270.260.040.49
20280.270.040.49
20290.270.040.49
20300.270.050.50

Louisiana Waterthrush Survey Routes in New Hampshire

Routes recording Louisiana Waterthrush 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 →
Canterbury320251991
Walpole320251976
Fitzwilliam220241990
Concord220251992
Strafford220211981
Marlow220251967
East Kingston220242001
Glen220251975
Peterborough120251967
Brentwood119981991
Dover120181993
Hopkinton120252006
Epsom119951976
Gilmantn I W119921992
Wilmot119751971
Mt Chocorua120251972
Jefferson Hl119771967
Franconia119741966

Louisiana Waterthrush Population Trend in Other States

alabamaarkansasconnecticutdelawarefloridageorgiaillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourinew-jerseynew-yorknorth-carolinaohiooklahomapennsylvaniarhode-islandsouth-carolinatennesseetexasvermontvirginiawest-virginiawisconsin

Source: USGS North American Breeding Bird Survey, retrieved 2026-08-14.