BirdAnalyst
Species · BCR 26 · BBS 2025 Release · 1966–2024

Black-crowned Night Heron In Mississippi Alluvial Valley

All regionsMississippi Alluvial ValleyWetland birds

Black-crowned Night Heron in Mississippi Alluvial Valley has surged: up 94% on the route-weighted index since 1970.

+94%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 →
32Routes 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 →
45YearsYears 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 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 →

Black-crowned Night Heron has surged in Mississippi Alluvial Valley: up 94% on the route-weighted index since 1970.

Black-crowned Night Heron In Mississippi Alluvial Valley Population Forecast

If the recent trend holds, Black-crowned Night Heron in Mississippi Alluvial Valley is projected to rise about 207% by 2029 — from 0.12 in 2024 to a central estimate of 0.37 (95% range 0.00–0.82). A 5-year backtest shows a typical error of ±101.3%, with 100% of held-out values landing inside the 95% band.

+207%Change 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 →
0.37Projected 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 →
0.00–0.8295% 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 →
±101.3%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 Mississippi Alluvial Valley is projected to rise about 207% by 2029 — from 0.12 in 2024 to a central estimate of 0.37 (95% range 0.00–0.82). A 5-year backtest shows a typical error of ±101.3%, 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 →
20250.350.000.81
20260.360.000.81
20270.360.000.82
20280.370.000.82
20290.370.000.82

Routes In Mississippi Alluvial Valley

Routes recording Black-crowned Night Heron in Mississippi Alluvial Valley.
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 →
River RoadLOUISIANA372010
BerwickLOUISIANA62018
Tensas NwrLOUISIANA42015
ShawLOUISIANA32023
FrogmoreLOUISIANA32023
Morgan CityLOUISIANA32014
AtchafalayaLOUISIANA32022
BlodgettMISSOURI32015
HughesARKANSAS21979
Morgan CityLOUISIANA21977
LaroseLOUISIANA21990
BrousvilleLOUISIANA21999
Baton RougeLOUISIANA22023
Eagle LakeMISSISSIPPI22024
DeventerMISSOURI21993
South BendARKANSAS11981
CarlisleLOUISIANA11988
FreetownLOUISIANA11994
KeystoneLOUISIANA12005
MayflowerLOUISIANA12017
RayvilleLOUISIANA12008
RamahLOUISIANA12024
GibsonLOUISIANA12019
BelairLOUISIANA12011
KraemerLOUISIANA12022

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