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

Green Heron Population Trend in Connecticut

All statesWetland birds

Green Heron in Connecticut has declined: down 46% on the route-weighted index since 1969.

-46%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 →
17Routes 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 →
50YearsYears 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 ConnecticutNotable 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 Connecticut. See the full index history below.

Green Heron Population Forecast in Connecticut

If the recent trend holds, Green Heron in Connecticut is projected to fall about 39% by 2028 — from 0.27 in 2023 to a central estimate of 0.17 (95% range 0.00–0.42). A 5-year backtest shows a typical error of ±66.4%, with 100% of held-out values landing inside the 95% band.

-39%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 →
0.17Projected 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 →
0.00–0.4295% 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 →
±66.4%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 Connecticut is projected to fall about 39% by 2028 — from 0.27 in 2023 to a central estimate of 0.17 (95% range 0.00–0.42). A 5-year backtest shows a typical error of ±66.4%, with 100% of held-out values landing inside the 95% band.19672028
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 →
20240.180.000.44
20250.180.000.43
20260.170.000.43
20270.170.000.42
20280.170.000.42

Green Heron Survey Routes in Connecticut

Routes recording Green Heron in Connecticut.
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 →
Granby420161991
Warren220101975
Long Hill219901973
Mystic120231973
E Hartland119881967
Buckingham120131989
Uncasville120172015
Woodstock119951977
Westbrook120111973
Willimantic120051969
No Woodbury120141969
Sherman120021973
Greenwich120171981
Danbury120101968
Mid Haddam120231974
Southington120231990
New Hartford119851972

Green Heron Population Trend in Other States

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

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