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

Green Heron Population Trend in Pennsylvania

All statesWetland birds

Green Heron in Pennsylvania has fallen sharply: down 54% on the route-weighted index since 1968.

-54%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 →
123Routes 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 Green Heron Trends in PennsylvaniaNotable 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 declinecomputed 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 →

Green Heron has fallen sharply in Pennsylvania: down 54% on the route-weighted index since 1968.

Green Heron Population Forecast in Pennsylvania

If the recent trend holds, Green Heron in Pennsylvania is projected to fall about 35% by 2029 — from 0.28 in 2024 to a central estimate of 0.18 (95% range 0.03–0.34). A 5-year backtest shows a typical error of ±23%, with 100% of held-out values landing inside the 95% band.

-35%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 →
0.18Projected 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 →
0.03–0.3495% 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 →
±23%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 Pennsylvania is projected to fall about 35% by 2029 — from 0.28 in 2024 to a central estimate of 0.18 (95% range 0.03–0.34). A 5-year backtest shows a typical error of ±23%, 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 →
20250.200.050.36
20260.200.040.36
20270.190.040.35
20280.190.030.34
20290.180.030.34

Green Heron Survey Routes in Pennsylvania

Routes recording Green Heron in Pennsylvania.
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 →
Eldred420151975
Drehersville 2420242001
Hop Bottom320151967
Honesdale320241972
Parkwood320191979
Brunnerville320071969
Schaefferstown 2320182002
Shrewsbury320121991
Slippery Rk219921971
Espyville220241970
Ferris Crnrs220241971
N Pine Grove220221971
Betula220161975
Russell City219721972
Ridgway220182008
Starlight219881970
Greentown220191969
Poyntelle220241979
Portersville219761973
Beaver220231972
Kaylor220181969
Clear Spring220131968
Mt Gretna219881966
Scheafferstn219761966
Clearfield220211968

Green Heron Population Trend in Other States

alabamaarizonaarkansascaliforniaconnecticutdelawarefloridageorgiaillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourinebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonrhode-islandsouth-carolinasouth-dakotatennesseetexasvermontvirginiawashingtonwest-virginiawisconsin

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