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

Great Blue Heron Population Trend in Delaware

All statesWetland birds

Great Blue Heron in Delaware has surged: up 34× on the route-weighted index since 1968.

34×Since 1968
17Routes In State
58Years

Notable Great Blue Heron Trends in Delaware

long arc increasecomputed index

Great Blue Heron has surged in Delaware: up 34× 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 fall about 50% by 2029 — from 12 in 2024 to a central estimate of 6.2 (95% range 3.9–8.5). A 5-year backtest shows a typical error of ±24%, with 60% of held-out values landing inside the 95% band.

-50%Change by 2029
6.2Projected 2029 index
3.9–8.595% range
±24%Backtest error
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 index95% low95% high
20255.83.58.1
20265.93.68.2
20276.03.78.3
20286.13.88.4
20296.23.98.5

Great Blue Heron Survey Routes in Delaware

Routes recording Great Blue Heron in Delaware.
Harrington3820241968
Blackbird2320241994
Lowes Xrds1319911967
Holleyville720041967
Mt Pleasant520191967
Pepperbox 2520232017
Holleyville 2420182006
Wilmington320141971
Pepperbox320161998
Frederica220131969
Dover219871974
Frankford220121969
Bethany Bch219901966
Milton220161985
Millsboro120242017
Georgetown120181992
Milton 2120172017

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 2026-05-22.