BirdAnalyst
Species · BBS 2025 Release · 1966–2024

unid Black-crowned / Yellow-crowned Night Heron

ArdeidaeWetland birdsNycticorax / Nyctanassa nycticorax / violacea

unid Black-crowned / Yellow-crowned Night Heron has no long-term trend on record.

n/aSince n/aTrendPercent 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 →
27RoutesSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
25Years SurveyedYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

About the unid Black-crowned / Yellow-crowned Night Heron

The unid Black-crowned / Yellow-crowned Night Heron (Nycticorax / Nyctanassa nycticorax / violacea) is a North American member of the Herons, Egrets & Bitterns (Ardeidae). In this analysis it is grouped with the wetland birds.

Size
12–51 in long (30–130 cm) — a long-legged wader (typical for the family)
Habitat
Marshes, ponds, lakeshores and other freshwater wetlands.
Diet
Aquatic invertebrates, small fish, frogs and plant matter.
Range
Recorded on 27 Breeding Bird Survey routes across 10 states, most concentrated in the Gulf Coastal Prairie.
Family
Ardeidae · Wetland birds

Notable unid Black-crowned / Yellow-crowned Night Heron TrendsNotable 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 unid Black-crowned / Yellow-crowned Night Heron. See the full index history below.

unid Black-crowned / Yellow-crowned Night Heron Population Forecast

If the recent trend holds, unid Black-crowned / Yellow-crowned Night Heron is projected to stay roughly flat through 2029, near 0.00 (95% range 0.00–0.00). A 5-year backtest shows a typical error of ±265.3%, with 80% 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 →
0.00–0.0095% 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 →
±265.3%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, unid Black-crowned / Yellow-crowned Night Heron is projected to stay roughly flat through 2029, near 0.00 (95% range 0.00–0.00). A 5-year backtest shows a typical error of ±265.3%, with 80% of held-out values landing inside the 95% band.19922029
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 →
20250.000.000.00
20260.000.000.00
20270.000.000.00
20280.000.000.00
20290.000.000.00

Where the unid Black-crowned / Yellow-crowned Night Heron Is Detected

BBS routes recording unid Black-crowned / Yellow-crowned Night Heron, sized by most recent count.

unid Black-crowned / Yellow-crowned Night Heron Population Trend by State

unid Black-crowned / Yellow-crowned Night Heron population trend by state.
TrendPercent 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 →Baseline yearThe first year of the smoothed window the trend is measured from. An earlier baseline means a longer record stands behind the number.Full methodology →Survey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
Alabamainsufficient datan/a1
Californiainsufficient datan/a1
Floridainsufficient datan/a3
Georgiainsufficient datan/a2
Indianainsufficient datan/a1
Louisianainsufficient datan/a9
Mississippiinsufficient datan/a1
Oklahomainsufficient datan/a1
South Carolinainsufficient datan/a2
Texasinsufficient datan/a6

unid Black-crowned / Yellow-crowned Night Heron Population Trend by Region

Bird Conservation Regions are the ecological unit for trends.

unid Black-crowned / Yellow-crowned Night Heron population trend by Bird Conservation Region.
TrendPercent 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 →Baseline yearThe first year of the smoothed window the trend is measured from. An earlier baseline means a longer record stands behind the number.Full methodology →Survey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
Gulf Coastal Prairie+51%20008

unid Black-crowned / Yellow-crowned Night Heron Conservation Status

unid Black-crowned / Yellow-crowned Night Heron is tracked across BBS survey routes; no formal conservation-status flag is recorded here.

Source: USGS North American Breeding Bird Survey, retrieved 2026-05-22. Trend is a route-weighted relative-abundance index, not an absolute population.