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Species · Minnesota · BBS 2025 Release · 1966–2024

Black-crowned Night Heron Population Trend in Minnesota

All statesWetland birds

Black-crowned Night Heron in Minnesota 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 →
25Routes 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 →
40YearsYears 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 MinnesotaNotable 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 Minnesota: down 95% on the route-weighted index since 1970.

Black-crowned Night Heron Population Forecast in Minnesota

If the recent trend holds, Black-crowned Night Heron in Minnesota is projected to stay roughly flat through 2021, near 0.00 (95% range 0.00–0.16). A 5-year backtest shows a typical error of ±198%, with 100% of held-out values landing inside the 95% band.

n/aChange by 2021TrendPercent 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 2021 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–0.1695% 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 →
±198%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 Minnesota is projected to stay roughly flat through 2021, near 0.00 (95% range 0.00–0.16). A 5-year backtest shows a typical error of ±198%, with 100% of held-out values landing inside the 95% band.19672021
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 →
20170.000.000.16
20180.000.000.16
20190.000.000.16
20200.000.000.16
20210.000.000.16

Black-crowned Night Heron Survey Routes in Minnesota

Routes recording Black-crowned Night Heron in Minnesota.
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 →
Hartland1019671967
Lude419921992
Tenney319901990
Money Creek219991998
Arlington219961969
Big Stone220081995
Osseo219911979
Knapp219841969
Gluek219841970
Le Center219991998
Sherburne Nr119911990
Chandler119831977
Ash Creek119951977
Lakeville120141969
Minnetonka120041970
Courtland120121987
Dawson119891989
Chokio119801978
Glyndon120052005
Grygla120031994
Badger120012001
New London119991999
Chokio North120082008
Mcgregor119951995
Ashby120161997

Black-crowned Night Heron Population Trend in Other States

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

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