BirdAnalyst
Species · BCR 12 · BBS 2026 Release · 1966–2025

Northern Harrier In Boreal Hardwood Transition

All regionsBoreal Hardwood TransitionBirds of prey

Northern Harrier in Boreal Hardwood Transition has fallen sharply: down 50% on the route-weighted index since 1968.

-50%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 →
87Routes 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 →
59YearsYears 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 →

Northern Harrier has fallen sharply in Boreal Hardwood Transition: down 50% on the route-weighted index since 1968.

Northern Harrier In Boreal Hardwood Transition Population Forecast

If the recent trend holds, Northern Harrier in Boreal Hardwood Transition is projected to rise about 105% by 2030 — from 0.10 in 2025 to a central estimate of 0.20 (95% range 0.00–0.40). A 5-year backtest shows a typical error of ±122.3%, with 100% of held-out values landing inside the 95% band.

+105%Change 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 →
0.20Projected 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 →
0.00–0.4095% 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 →
±122.3%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, Northern Harrier in Boreal Hardwood Transition is projected to rise about 105% by 2030 — from 0.10 in 2025 to a central estimate of 0.20 (95% range 0.00–0.40). A 5-year backtest shows a typical error of ±122.3%, with 100% of held-out values landing inside the 95% band.19662030
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 →
20260.200.000.40
20270.200.000.40
20280.200.000.40
20290.200.000.40
20300.200.000.40

Routes In Boreal Hardwood Transition

Routes recording Northern Harrier 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 →
Wigwam BayMINNESOTA32023
BayfieldWISCONSIN32025
Crystal FlsMICHIGAN21992
SkeelsMICHIGAN21989
Beaver LakeMICHIGAN21970
Hubbard LakeMICHIGAN21993
Seney NwrMICHIGAN22018
Island LakeMINNESOTA22017
DebsMINNESOTA22019
WaskishMINNESOTA22021
BrainerdMINNESOTA22024
BagleyMINNESOTA22006
Nett LakeMINNESOTA22018
PhillipsWISCONSIN22022
OntonagonMICHIGAN11967
BootjackMICHIGAN12009
Ned LakeMICHIGAN11988
Gibbs CityMICHIGAN12006
Maple GroveMICHIGAN12024
IshpemingMICHIGAN11981
Brocky LakeMICHIGAN12018
WilsonMICHIGAN12009
CunardMICHIGAN11994
ShingletonMICHIGAN12005
IsabellaMICHIGAN12004

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