BirdAnalyst
Species · BCR 23 · BBS 2026 Release · 1966–2025

Northern Harrier In Prairie Hardwood Transition

All regionsPrairie Hardwood TransitionBirds of prey

Northern Harrier in Prairie Hardwood Transition has fallen sharply: down 74% on the route-weighted index since 1968.

-74%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 →
108Routes 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 Prairie Hardwood Transition: down 74% on the route-weighted index since 1968.

Northern Harrier In Prairie Hardwood Transition Population Forecast

If the recent trend holds, Northern Harrier in Prairie Hardwood Transition is projected to rise about 128% by 2030 — from 0.09 in 2025 to a central estimate of 0.19 (95% range 0.03–0.36). A 5-year backtest shows a typical error of ±160.5%, with 80% of held-out values landing inside the 95% band.

+128%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 →
0.19Projected 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 →
0.03–0.3695% 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 →
±160.5%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 Prairie Hardwood Transition is projected to rise about 128% by 2030 — from 0.09 in 2025 to a central estimate of 0.19 (95% range 0.03–0.36). A 5-year backtest shows a typical error of ±160.5%, with 80% 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 →
20260.200.030.37
20270.200.030.37
20280.200.030.36
20290.200.030.36
20300.190.030.36

Routes In Prairie Hardwood Transition

Routes recording Northern Harrier in Prairie 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 →
NapoleonOHIO31996
No BradleyMICHIGAN21994
OwendaleMICHIGAN21992
S LyonsMICHIGAN21970
ChatfieldMINNESOTA21970
OsseoMINNESOTA22019
KnappMINNESOTA22019
Whitewater 2MINNESOTA22016
DresserWISCONSIN22022
LoraineWISCONSIN22018
Rolling PrWISCONSIN22017
MerideanWISCONSIN22009
Buena VistaWISCONSIN22022
GreshamWISCONSIN22025
AnnatonWISCONSIN22021
GuilfordILLINOIS11998
Lake GalenaILLINOIS12007
EllisINDIANA12015
FestinaIOWA12003
ScottvilleMICHIGAN11976
LawrenceMICHIGAN12008
New TroyMICHIGAN12005
Big RapidsMICHIGAN11981
NashvilleMICHIGAN12005
CoopersvilleMICHIGAN12003

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