BirdAnalyst
Species · Arizona · BBS 2025 Release · 1966–2024

Black-crowned Night Heron Population Trend in Arizona

All statesWetland birds

Black-crowned Night Heron in Arizona has fallen sharply: down 60% on the route-weighted index since 1985.

-60%Since 1985TrendPercent 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 →
8Routes 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 →
22YearsYears 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 ArizonaNotable 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 Arizona: down 60% on the route-weighted index since 1985.

Black-crowned Night Heron Population Forecast in Arizona

If the recent trend holds, Black-crowned Night Heron in Arizona is projected to fall about 93% by 2028 — from 0.13 in 2023 to a central estimate of 0.01 (95% range 0.00–0.14). A 5-year backtest shows a typical error of ±44.4%, with 100% of held-out values landing inside the 95% band.

-93%Change by 2028TrendPercent 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 →
0.01Projected 2028 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–0.1495% 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 →
±44.4%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 Arizona is projected to fall about 93% by 2028 — from 0.13 in 2023 to a central estimate of 0.01 (95% range 0.00–0.14). A 5-year backtest shows a typical error of ±44.4%, with 100% of held-out values landing inside the 95% band.19742028
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 →
20240.020.000.16
20250.020.000.15
20260.020.000.15
20270.010.000.15
20280.010.000.14

Black-crowned Night Heron Survey Routes in Arizona

Routes recording Black-crowned Night Heron in Arizona.
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 →
Palo Verde 2520232015
Carr Mtn220021996
Cibola Lake120021994
Palo Verde120122000
Araby120111996
Hunt119991999
Toroweap120172017
Laguna120111974

Black-crowned Night Heron Population Trend in Other States

alabamaarkansascaliforniacoloradoconnecticutdelawarefloridageorgiaidahoillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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