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Species · Pennsylvania · BBS 2025 Release · 1966–2024

Black-crowned Night Heron Population Trend in Pennsylvania

All statesWetland birds

Black-crowned Night Heron in Pennsylvania has declined: down 46% on the route-weighted index since 1970.

-46%Since 1970TrendPercent 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 →
24Routes 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 →
44YearsYears 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 PennsylvaniaNotable 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 Pennsylvania. See the full index history below.

Black-crowned Night Heron Population Forecast in Pennsylvania

If the recent trend holds, Black-crowned Night Heron in Pennsylvania is projected to stay roughly flat through 2029, near 0.02 (95% range 0.00–0.07). A 5-year backtest shows a typical error of ±128.8%, with 100% of held-out values landing inside the 95% band.

n/aChange 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 →
0.02Projected 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 →
0.00–0.0795% 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 →
±128.8%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 Pennsylvania is projected to stay roughly flat through 2029, near 0.02 (95% range 0.00–0.07). A 5-year backtest shows a typical error of ±128.8%, with 100% of held-out values landing inside the 95% band.19682029
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 →
20250.030.000.07
20260.030.000.07
20270.030.000.07
20280.020.000.07
20290.020.000.07

Black-crowned Night Heron Survey Routes in Pennsylvania

Routes recording Black-crowned Night 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 →
Ephrata519811981
Quakertown419731973
Williamsburg320222022
Scheafferstn319751969
Austinville219701970
Schaefferstown 2220132013
Peters Mt219931993
Sporting Hil219771977
Brunnerville219881977
Espyville119981998
Ferris Crnrs119911991
Leola120231999
Pocono Summit119681968
Landisburg119911978
Elizabethvil120241996
Mount Joy119961978
Bendersville120102010
Jacobus120151987
Clear Spring120172017
Mifflintown120132013
Middletown120071976
Mt Gretna119911970
Pottstown119791979
Labott119791970

Black-crowned Night Heron Population Trend in Other States

alabamaarizonaarkansascaliforniacoloradoconnecticutdelawarefloridageorgiaidahoillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonrhode-islandsouth-carolinasouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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