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

Northern Harrier Population Trend in Oregon

All statesGeneralists

Northern Harrier in Oregon has surged: up 189% on the route-weighted index since 1970.

+189%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 →
66Routes 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 →
56YearsYears 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 189% 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 fall about 25% by 2029 — from 0.72 in 2024 to a central estimate of 0.54 (95% range 0.20–0.88). A 5-year backtest shows a typical error of ±61.9%, with 100% of held-out values landing inside the 95% band.

-25%Change 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 →
0.54Projected 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 →
0.20–0.8895% 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 →
±61.9%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 fall about 25% by 2029 — from 0.72 in 2024 to a central estimate of 0.54 (95% range 0.20–0.88). A 5-year backtest shows a typical error of ±61.9%, with 100% of held-out values landing inside the 95% band.19682029
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 →
20250.530.190.87
20260.530.190.87
20270.530.190.88
20280.540.200.88
20290.540.200.88

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 →
Flook Lake920241994
Princeton619851972
Blitzen 2520241994
Pendleton520241981
Madras420241997
Harney Lake420241993
Warner Vally420241994
Bowden Hills420241999
Mcminnville420241995
Lone Rock320241968
Ordnance319791972
Malheur Nwr319981986
Blitzen319921971
Adair320241981
Sparta319991972
Battle Mtn320241985
Umatilla320221988
Three Forks220242006
Joseph220241975
Eightmile220241982
Blizzard Gap220191984
Fish Lake220241972
Canby220171995
Mikkalo220211999
Crane220241994

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 2026-05-22.