BirdAnalyst
Species · BCR 29 · BBS 2025 Release · 1966–2024

Black-crowned Night Heron In Piedmont

All regionsPiedmontWetland birds

Black-crowned Night Heron in Piedmont has fallen sharply: down 72% on the route-weighted index since 1974.

-72%Since 1974TrendPercent 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 RegionSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
46YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable SignalsNotable 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 declinecomputed 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 →

Black-crowned Night Heron has fallen sharply in Piedmont: down 72% on the route-weighted index since 1974.

Black-crowned Night Heron In Piedmont Population Forecast

If the recent trend holds, Black-crowned Night Heron in Piedmont is projected to stay roughly flat through 2029, near 0.00 (95% range 0.00–0.15). A 5-year backtest shows a typical error of ±110.3%, 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 →
0.00Projected 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 →
0.00–0.1595% 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 →
±110.3%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 Piedmont is projected to stay roughly flat through 2029, near 0.00 (95% range 0.00–0.15). A 5-year backtest shows a typical error of ±110.3%, with 100% of held-out values landing inside the 95% band.19702029
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 →
20250.000.000.15
20260.000.000.15
20270.000.000.15
20280.000.000.15
20290.000.000.15

Routes In Piedmont

Routes recording Black-crowned Night Heron in Piedmont.
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 →
EphrataPENNSYLVANIA51981
IjamsvilleMARYLAND22023
FairviewNORTH-CAROLINA22008
Sporting HilPENNSYLVANIA21977
Nixburg 2ALABAMA12001
Lincolnton 2GEORGIA12019
OlneyMARYLAND12024
TheodoreMARYLAND12010
WheatonMARYLAND12024
Mt GretnaPENNSYLVANIA11991
PottstownPENNSYLVANIA11979
LabottPENNSYLVANIA11979
Mount JoyPENNSYLVANIA11996
BendersvillePENNSYLVANIA12010
JacobusPENNSYLVANIA12015
LeolaPENNSYLVANIA12023
HallVIRGINIA12006

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