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

Great Blue Heron Population Trend in New Hampshire

All statesWetland birds

Great Blue Heron in New Hampshire has surged: up 83% on the route-weighted index since 1968.

+83%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 →
24Routes 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 →
58YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Great Blue Heron 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 →

Great Blue Heron has surged in New Hampshire: up 83% on the route-weighted index since 1968.

Great Blue Heron Population Forecast in New Hampshire

If the recent trend holds, Great Blue Heron in New Hampshire is projected to rise about 44% by 2029 — from 0.36 in 2024 to a central estimate of 0.53 (95% range 0.04–1.0). A 5-year backtest shows a typical error of ±116.7%, with 100% of held-out values landing inside the 95% band.

+44%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 →
0.53Projected 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 →
0.04–1.095% 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 →
±116.7%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, Great Blue Heron in New Hampshire is projected to rise about 44% by 2029 — from 0.36 in 2024 to a central estimate of 0.53 (95% range 0.04–1.0). A 5-year backtest shows a typical error of ±116.7%, with 100% 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 →
20250.520.041.0
20260.520.041.0
20270.520.041.0
20280.520.041.0
20290.530.041.0

Great Blue Heron Survey Routes in New Hampshire

Routes recording Great Blue Heron 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 →
Jefferson Hl719951985
Brentwood319971969
Lempster320221979
Strafford220241967
Peterborough120191967
Fitzwilliam120241968
Dover120241966
Hopkinton120191975
Epsom120181966
Concord120181969
Canterbury120241967
Gilmantn I W120181970
Wilmot120241985
Mt Chocorua120241975
Walpole120241975
Marlow120211972
Franconia120231977
Milan120141975
Stratford120091971
Dixvil Notch120081971
Clarksville120071975
Glen120191989
East Kingston120222001
Jeffers Ntch120212003

Great Blue Heron Population Trend in Other States

alabamaalaskaarizonaarkansascaliforniacoloradoconnecticutdelawarefloridageorgiaidahoillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanevadanew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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