BirdAnalyst
Species · Colorado · BBS 2026 Release · 1966–2025

Black-crowned Night Heron Population Trend in Colorado

All statesWetland birds

Black-crowned Night Heron in Colorado has collapsed: down 95% on the route-weighted index since 1970.

-95%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 →
20Routes 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 →
47YearsYears 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 ColoradoNotable 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 collapsed in Colorado: down 95% on the route-weighted index since 1970.

Black-crowned Night Heron Population Forecast in Colorado

If the recent trend holds, Black-crowned Night Heron in Colorado is projected to stay roughly flat through 2030, near 0.00 (95% range 0.00–0.21). A 5-year backtest shows a typical error of ±128.9%, with 100% of held-out values landing inside the 95% band.

n/aChange 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 →
0.00Projected 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 →
0.00–0.2195% 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 →
±128.9%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 Colorado is projected to stay roughly flat through 2030, near 0.00 (95% range 0.00–0.21). A 5-year backtest shows a typical error of ±128.9%, with 100% of held-out values landing inside the 95% band.19682030
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 →
20260.000.000.21
20270.000.000.21
20280.000.000.21
20290.000.000.21
20300.000.000.21

Black-crowned Night Heron Survey Routes in Colorado

Routes recording Black-crowned Night Heron in Colorado.
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 →
Rio Grnds Rs1219991993
Buford319841984
Neegrande320181998
Last Chance220041988
Powderhorn219991999
Mosca220081999
San Luis220091997
Harmony119951979
Arsenal120091993
Arsenal 2120252025
Moffat119791970
Dolores119851968
Blanca119801980
Walden120192019
Hudson120131988
Pinos Creek119881988
Alamosa120251991
Groundhog Rs119941994
Moon Pass120031998
Lake City 2120182018

Black-crowned Night Heron Population Trend in Other States

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

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