BirdAnalyst
Species · BCR 26 · BBS 2026 Release · 1966–2025

Yellow-crowned Night Heron In Mississippi Alluvial Valley

All regionsMississippi Alluvial ValleyWetland birds

Yellow-crowned Night Heron in Mississippi Alluvial Valley has surged: up 171% on the route-weighted index since 1969.

+171%Since 1969TrendPercent 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 →
44Routes 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 →
58YearsYears 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 →

Yellow-crowned Night Heron has surged in Mississippi Alluvial Valley: up 171% on the route-weighted index since 1969.

Yellow-crowned Night Heron In Mississippi Alluvial Valley Population Forecast

If the recent trend holds, Yellow-crowned Night Heron in Mississippi Alluvial Valley is projected to rise about 150% by 2030 — from 1.6 in 2025 to a central estimate of 3.9 (95% range 0.00–9.1). A 5-year backtest shows a typical error of ±255.5%, with 100% of held-out values landing inside the 95% band.

+150%Change by 2030TrendPercent 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 →
3.9Projected 2030 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–9.195% 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 →
±255.5%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, Yellow-crowned Night Heron in Mississippi Alluvial Valley is projected to rise about 150% by 2030 — from 1.6 in 2025 to a central estimate of 3.9 (95% range 0.00–9.1). A 5-year backtest shows a typical error of ±255.5%, with 100% of held-out values landing inside the 95% band.19672030
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 →
20263.80.009.0
20273.80.009.0
20283.90.009.0
20293.90.009.0
20303.90.009.1

Routes In Mississippi Alluvial Valley

Routes recording Yellow-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 →
RamahLOUISIANA392025
Morgan CityLOUISIANA231986
KeystoneLOUISIANA122013
AtchafalayaLOUISIANA92025
South BendARKANSAS41980
CarlisleLOUISIANA31988
ShawLOUISIANA32024
LaroseLOUISIANA31990
KraemerLOUISIANA32025
KelsoARKANSAS22011
FreetownLOUISIANA22019
MayflowerLOUISIANA22025
GibsonLOUISIANA22015
GonzalesLOUISIANA22010
FrogmoreLOUISIANA22025
Rayville 2LOUISIANA22023
Baton RougeLOUISIANA22014
Tchula 2MISSISSIPPI21980
Delta N.F.MISSISSIPPI21996
EudoraARKANSAS12016
HughesARKANSAS11979
HarrisburgARKANSAS11996
MaynardARKANSAS11992
WilsonARKANSAS11997
Crowley'S RidgeARKANSAS12019

Source: USGS North American Breeding Bird Survey, retrieved 2026-08-14.