BirdAnalyst
Species · Delaware · BBS 2026 Release · 1966–2025

Great Blue Heron Population Trend in Delaware

All statesWetland birds

Great Blue Heron in Delaware has surged: up 32× on the route-weighted index since 1968.

32×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 →
59YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Great Blue 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 →

Great Blue Heron has surged in Delaware: up 32× on the route-weighted index since 1968.

Great Blue Heron Population Forecast in Delaware

If the recent trend holds, Great Blue Heron in Delaware is projected to rise about 53% by 2030 — from 4.0 in 2025 to a central estimate of 6.1 (95% range 3.8–8.4). A 5-year backtest shows a typical error of ±28.2%, with 60% of held-out values landing inside the 95% band.

+53%Change by 2030TrendPercent 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 →
6.1Projected 2030 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
3.8–8.495% 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 →
±28.2%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, Great Blue Heron in Delaware is projected to rise about 53% by 2030 — from 4.0 in 2025 to a central estimate of 6.1 (95% range 3.8–8.4). A 5-year backtest shows a typical error of ±28.2%, with 60% of held-out values landing inside the 95% band.19662030
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 →
20265.73.48.1
20275.83.58.2
20285.93.68.2
20296.03.78.3
20306.13.88.4

Great Blue Heron Survey Routes in Delaware

Routes recording Great Blue 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 →
Lowes Xrds1319911967
Harrington1120251968
Holleyville720041967
Mt Pleasant520191967
Milton 2520252017
Holleyville 2420182006
Pepperbox 2420252017
Wilmington320141971
Pepperbox320161998
Dover219871974
Frankford220121969
Bethany Bch219901966
Milton220161985
Blackbird220251994
Frederica120251969
Millsboro120252017
Georgetown120181992

Great Blue Heron Population Trend in Other States

alabamaalaskaarizonaarkansascaliforniacoloradoconnecticutfloridageorgiaidahoillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

Source: USGS North American Breeding Bird Survey, retrieved 2026-08-14.