BirdAnalyst
Species · Massachusetts · BBS 2025 Release · 1966–2024

Green Heron Population Trend in Massachusetts

All statesWetland birds

Green Heron in Massachusetts has edged down: down 22% on the route-weighted index since 1969.

-22%Since 1969TrendPercent 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 →
28Routes 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 →
55YearsYears 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 MassachusettsNotable 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 Massachusetts. See the full index history below.

Green Heron Population Forecast in Massachusetts

If the recent trend holds, Green Heron in Massachusetts is projected to rise about 140% by 2029 — from 0.07 in 2024 to a central estimate of 0.16 (95% range 0.00–0.46). A 5-year backtest shows a typical error of ±100.3%, with 80% of held-out values landing inside the 95% band.

+140%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 →
0.16Projected 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 →
0.00–0.4695% 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 →
±100.3%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 Massachusetts is projected to rise about 140% by 2029 — from 0.07 in 2024 to a central estimate of 0.16 (95% range 0.00–0.46). A 5-year backtest shows a typical error of ±100.3%, with 80% of held-out values landing inside the 95% band.19672029
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 →
20250.170.000.47
20260.170.000.46
20270.170.000.46
20280.160.000.46
20290.160.000.46

Green Heron Survey Routes in Massachusetts

Routes recording Green Heron in Massachusetts.
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 →
Pittsfield420051988
Newburyport320111970
S Barre220231970
N. Andover220181995
Warren 2220122012
E Dennis120161973
Chilmark119751969
Marion120131969
Wellfleet120051970
Prattville120171968
Brockton119961969
Maynard120181968
Littleton120211970
N Oxford120122008
Mansfield120071993
Princeton119721972
E Pepperell119931967
Belchertown120151996
Warren120081970
N Orange120141972
Cummington119861969
Chesterfield120051971
Cheshire119941972
Sheffield120081975
Cape Cod Ns119921991

Green Heron Population Trend in Other States

alabamaarizonaarkansascaliforniaconnecticutdelawarefloridageorgiaillinoisindianaiowakansaskentuckylouisianamainemarylandmichiganminnesotamississippimissourinebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasvermontvirginiawashingtonwest-virginiawisconsin

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