BirdAnalyst
Species · Indiana · BBS 2025 Release · 1966–2024

Northern Harrier Population Trend in Indiana

All statesGeneralists

Northern Harrier in Indiana has fallen sharply: down 65% on the route-weighted index since 1971.

-65%Since 1971TrendPercent 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 →
23Routes 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 →
30YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Northern Harrier Trends in IndianaNotable 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 Indiana: down 65% on the route-weighted index since 1971.

Northern Harrier Population Forecast in Indiana

If the recent trend holds, Northern Harrier in Indiana is projected to stay roughly flat through 2029, near 0.03 (95% range 0.00–0.10). A 5-year backtest shows a typical error of ±52.4%, with 100% 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 →
0.03Projected 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 →
0.00–0.1095% 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 →
±52.4%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 Indiana is projected to stay roughly flat through 2029, near 0.03 (95% range 0.00–0.10). A 5-year backtest shows a typical error of ±52.4%, 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 →
20250.030.000.10
20260.030.000.10
20270.030.000.10
20280.030.000.10
20290.030.000.10

Northern Harrier Survey Routes in Indiana

Routes recording Northern Harrier in Indiana.
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 →
Hebron120142014
Kankakee Sands120232004
Ellis120151970
Fowler120041966
W Lafayette120111985
Galveston119911991
Middletown119881988
Swayzee120192019
Berne119871983
Pimento119981998
Brazil120152000
Jamestown120192019
Sexton120241991
Milroy120042000
Shelbyville120102010
Washington119871987
Millersburg120052003
Indian Spgs119971997
Evansville120022002
Crown Point120001999
Newberry120192005
Cyprss120052005
Kokomo120152015

Northern Harrier Population Trend in Other States

alabamaalaskaarizonaarkansascaliforniacoloradodelawaregeorgiaidahoillinoisiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniarhode-islandsouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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