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

Black-crowned Night Heron Population Trend in Delaware

All statesWetland birds

Black-crowned Night Heron in Delaware has increased: up 34% on the route-weighted index since 1972.

+34%Since 1972TrendPercent 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 →
8Routes 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 →
20YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Black-crowned Night 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 →

No notable trend signals for Black-crowned Night Heron in Delaware. See the full index history below.

Black-crowned Night Heron Population Forecast in Delaware

If the recent trend holds, Black-crowned Night Heron in Delaware is projected to fall about 37% by 2024 — from 0.43 in 2019 to a central estimate of 0.27 (95% range 0.00–0.70). A 5-year backtest shows a typical error of ±42.2%, with 100% of held-out values landing inside the 95% band.

-37%Change by 2024TrendPercent 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 →
0.27Projected 2024 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–0.7095% 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 →
±42.2%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, Black-crowned Night Heron in Delaware is projected to fall about 37% by 2024 — from 0.43 in 2019 to a central estimate of 0.27 (95% range 0.00–0.70). A 5-year backtest shows a typical error of ±42.2%, with 100% of held-out values landing inside the 95% band.19682024
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 →
20200.270.000.70
20210.270.000.70
20220.270.000.70
20230.270.000.70
20240.270.000.70

Black-crowned Night Heron Survey Routes in Delaware

Routes recording Black-crowned Night 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 →
Dover319681968
Holleyville 2320192019
Harrington220031974
Mt Pleasant119871987
Wilmington119921969
Bethany Bch119901976
Blackbird120111995
Pepperbox120012001

Black-crowned Night Heron Population Trend in Other States

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

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