BirdAnalyst
Species · BCR 10 · BBS 2025 Release · 1966–2024

Black-crowned Night Heron In Northern Rockies

All regionsNorthern RockiesWetland birds

Black-crowned Night Heron in Northern Rockies has fallen sharply: down 58% on the route-weighted index since 1979.

-58%Since 1979TrendPercent 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 →
18Routes 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 →
31YearsYears 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 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 Northern Rockies: down 58% on the route-weighted index since 1979.

Black-crowned Night Heron In Northern Rockies Population Forecast

If the recent trend holds, Black-crowned Night Heron in Northern Rockies is projected to stay roughly flat through 2024, near 0.01 (95% range 0.00–0.10). A 5-year backtest shows a typical error of ±88.4%, with 80% of held-out values landing inside the 95% band.

n/aChange by 2024TrendPercent 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 2024 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–0.1095% 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 →
±88.4%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 Northern Rockies is projected to stay roughly flat through 2024, near 0.01 (95% range 0.00–0.10). A 5-year backtest shows a typical error of ±88.4%, with 80% of held-out values landing inside the 95% band.19772024
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 →
20200.020.000.11
20210.020.000.11
20220.010.000.10
20230.010.000.10
20240.010.000.10

Routes In Northern Rockies

Routes recording Black-crowned Night Heron in Northern Rockies.
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 →
Neponset ResUTAH122018
HarmonyWYOMING61988
Saleratus CrUTAH22012
Crane CreekIDAHO12006
BeaverheadMONTANA11992
Red RockMONTANA12015
SpartaOREGON11992
RandolphUTAH12019
WoodruffUTAH12016
FontenelleWYOMING12007
Elk HornWYOMING12000
RiversideWYOMING11989
Hunter PeakWYOMING12003
Mtn ViewWYOMING11989
Green RiverWYOMING11982
RawlinsWYOMING11992
Rock RiverWYOMING11996
YellowstoneWYOMING11989

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