BirdAnalyst
Species · Oregon · BBS 2026 Release · 1966–2025

Northern Harrier Population Trend in Oregon

All statesBirds of prey

Northern Harrier in Oregon has surged: up 247% on the route-weighted index since 1970.

+247%Since 1970TrendPercent 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 →
68Routes 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 →
57YearsYears 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 OregonNotable 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 increasecomputed 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 surged in Oregon: up 247% on the route-weighted index since 1970.

Northern Harrier Population Forecast in Oregon

If the recent trend holds, Northern Harrier in Oregon is projected to stay roughly flat through 2030, near 0.54 (95% range 0.20–0.88). A 5-year backtest shows a typical error of ±61.1%, with 100% of held-out values landing inside the 95% band.

+5%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 →
0.54Projected 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 →
0.20–0.8895% 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 →
±61.1%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 Oregon is projected to stay roughly flat through 2030, near 0.54 (95% range 0.20–0.88). A 5-year backtest shows a typical error of ±61.1%, with 100% of held-out values landing inside the 95% band.19682030
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 →
20260.530.190.87
20270.530.190.87
20280.540.200.87
20290.540.200.88
20300.540.200.88

Northern Harrier Survey Routes in Oregon

Routes recording Northern Harrier in Oregon.
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 →
Battle Mtn720251985
Bowden Hills720251999
Princeton619851972
Pendleton520241981
Harney Lake420241993
Warner Vally420241994
Mcminnville420241995
Flook Lake420251994
Blitzen 2320251994
Lone Rock320241968
Ordnance319791972
Crowley320251984
Malheur Nwr319981986
Blitzen319921971
Alvord Lake320251968
Joseph320251975
Sparta320251972
Umatilla320221988
Trout Creek320251996
Adair220251981
Eightmile220241982
Blizzard Gap220191984
Fish Lake220241972
Crane220241994
Merrill220131993

Northern Harrier Population Trend in Other States

alabamaalaskaarizonaarkansascaliforniacoloradodelawaregeorgiaidahoillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomapennsylvaniarhode-islandsouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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