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

Green Heron Population Trend in New Hampshire

All statesWetland birds

Green Heron in New Hampshire has declined: down 37% on the route-weighted index since 1968.

-37%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 →
45YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Green 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 →

No notable trend signals for Green Heron in New Hampshire. See the full index history below.

Green Heron Population Forecast in New Hampshire

If the recent trend holds, Green Heron in New Hampshire is projected to fall about 14% by 2028 — from 0.09 in 2023 to a central estimate of 0.07 (95% range 0.00–0.21). A 5-year backtest shows a typical error of ±48.1%, with 100% of held-out values landing inside the 95% band.

-14%Change by 2028TrendPercent 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 →
0.07Projected 2028 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–0.2195% 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 →
±48.1%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, Green Heron in New Hampshire is projected to fall about 14% by 2028 — from 0.09 in 2023 to a central estimate of 0.07 (95% range 0.00–0.21). A 5-year backtest shows a typical error of ±48.1%, with 100% of held-out values landing inside the 95% band.19662028
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 →
20240.080.000.22
20250.080.000.22
20260.080.000.22
20270.080.000.21
20280.070.000.21

Green Heron Survey Routes in New Hampshire

Routes recording Green 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 Hl219951977
Stratford219951977
Peterborough120221971
Brentwood119731966
Fitzwilliam120211968
Dover120181970
Hopkinton119871987
Epsom120181967
Concord120231993
Strafford120091982
East Kingston120092006
Gilmantn I W119891989
Wilmot119811981
Mt Chocorua120212021
Marlow120231986
Lempster120071985
Milan119871967
Dixvil Notch120051968

Green Heron Population Trend in Other States

alabamaarizonaarkansascaliforniaconnecticutdelawarefloridageorgiaillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourinebraskanevadanew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasvermontvirginiawashingtonwest-virginiawisconsin

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