BirdAnalyst
Species · BCR 23 · BBS 2025 Release · 1966–2024

Northern Harrier In Prairie Hardwood Transition

All regionsPrairie Hardwood TransitionGeneralists

Northern Harrier in Prairie Hardwood Transition has fallen sharply: down 64% on the route-weighted index since 1968.

-64%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 →
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 →

Northern Harrier has fallen sharply in Prairie Hardwood Transition: down 64% 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 stay roughly flat through 2029, near 0.20 (95% range 0.04–0.37). A 5-year backtest shows a typical error of ±150.4%, with 80% of held-out values landing inside the 95% band.

n/aChange 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 →
0.20Projected 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 →
0.04–0.3795% 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 →
±150.4%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, Northern Harrier in Prairie Hardwood Transition is projected to stay roughly flat through 2029, near 0.20 (95% range 0.04–0.37). A 5-year backtest shows a typical error of ±150.4%, with 80% 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 →
20250.210.040.37
20260.210.040.37
20270.200.040.37
20280.200.040.37
20290.200.040.37

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
MerrillWISCONSIN22023
Rolling PrWISCONSIN22017
MerideanWISCONSIN22009
Buena VistaWISCONSIN22022
AnnatonWISCONSIN22021
GuilfordILLINOIS11998
Lake GalenaILLINOIS12007
EllisINDIANA12015
FestinaIOWA12003
ScottvilleMICHIGAN11976
LawrenceMICHIGAN12008
New TroyMICHIGAN12005
Big RapidsMICHIGAN11981
NashvilleMICHIGAN12005
CoopersvilleMICHIGAN12003

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