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

Green Heron Population Trend in Delaware

All statesWetland birds

Green Heron in Delaware has risen sharply: up 70% on the route-weighted index since 1968.

+70%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 →
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 →
56YearsYears 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 DelawareNotable 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 →

Green Heron has risen sharply in Delaware: up 70% on the route-weighted index since 1968.

Green Heron Population Forecast in Delaware

If the recent trend holds, Green Heron in Delaware is projected to rise about 21% by 2029 — from 1.0 in 2024 to a central estimate of 1.2 (95% range 0.37–2.0). A 5-year backtest shows a typical error of ±30.4%, with 100% of held-out values landing inside the 95% band.

+21%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 →
1.2Projected 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 →
0.37–2.095% 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 →
±30.4%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 Delaware is projected to rise about 21% by 2029 — from 1.0 in 2024 to a central estimate of 1.2 (95% range 0.37–2.0). A 5-year backtest shows a typical error of ±30.4%, 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 →
20251.20.362.0
20261.20.362.0
20271.20.372.0
20281.20.372.0
20291.20.372.0

Green Heron Survey Routes in Delaware

Routes recording Green Heron in Delaware.
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 →
Wilmington620121968
Bethany Bch619901966
Georgetown420211996
Milton 2320172017
Harrington220241968
Frederica220141967
Blackbird220241994
Mt Pleasant120191966
Dover119871966
Frankford120121968
Holleyville120031967
Lowes Xrds119911966
Milton120131969
Millsboro120242023
Holleyville 2120182006
Pepperbox120161998
Pepperbox 2120232018

Green Heron Population Trend in Other States

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

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