BirdAnalyst
Species · BCR 12 · BBS 2025 Release · 1966–2024

Great Blue Heron In Boreal Hardwood Transition

All regionsBoreal Hardwood TransitionWetland birds

Great Blue Heron in Boreal Hardwood Transition has fallen sharply: down 60% on the route-weighted index since 1968.

-60%Since 1968TrendPercent 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 →
110Routes 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 →
58YearsYears 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 →

Great Blue Heron has fallen sharply in Boreal Hardwood Transition: down 60% on the route-weighted index since 1968.

Great Blue Heron In Boreal Hardwood Transition Population Forecast

If the recent trend holds, Great Blue Heron in Boreal Hardwood Transition is projected to rise about 15% by 2029 — from 0.27 in 2024 to a central estimate of 0.31 (95% range 0.00–0.98). A 5-year backtest shows a typical error of ±195.2%, with 100% of held-out values landing inside the 95% band.

+15%Change 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 →
0.31Projected 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 →
0.00–0.9895% 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 →
±195.2%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, Great Blue Heron in Boreal Hardwood Transition is projected to rise about 15% by 2029 — from 0.27 in 2024 to a central estimate of 0.31 (95% range 0.00–0.98). A 5-year backtest shows a typical error of ±195.2%, with 100% of held-out values landing inside the 95% band.19662029
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 →
20250.360.001.0
20260.350.001.0
20270.330.001.0
20280.320.000.99
20290.310.000.98

Routes In Boreal Hardwood Transition

Routes recording Great Blue Heron in Boreal Hardwood Transition.
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 →
BemidjiMINNESOTA81980
IronsMICHIGAN41989
Hart LakeMINNESOTA42009
MontrealWISCONSIN42012
Bear LakeMICHIGAN32022
CohassetMINNESOTA32015
WarroadMINNESOTA32000
HermanMICHIGAN22015
CunardMICHIGAN22014
GilchristMICHIGAN22016
Brush CreekMICHIGAN21992
Red OakMICHIGAN22012
CathroMICHIGAN22016
Wigwam BayMINNESOTA22023
BrainerdMINNESOTA22024
Sawbill CampMINNESOTA21995
BagleyMINNESOTA22003
GlendaleMINNESOTA22018
Cass LakeMINNESOTA22012
Nett LakeMINNESOTA22014
Tamarac NwrMINNESOTA22024
Land O LakesWISCONSIN22016
CouderayWISCONSIN22019
GilmanWISCONSIN22019
IrmaWISCONSIN22024

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