BirdAnalyst
Species · North Dakota · BBS 2025 Release · 1966–2024

Northern Harrier Population Trend in North Dakota

All statesGeneralists

Northern Harrier in North Dakota has edged down: down 18% on the route-weighted index since 1969.

-18%Since 1969TrendPercent 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 →
50Routes 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 North DakotaNotable signalsLong-arc shifts the engine flags automatically — sustained declines or increases large enough to stand out from year-to-year noise.Full methodology →

No notable trend signals for Northern Harrier in North Dakota. See the full index history below.

Northern Harrier Population Forecast in North Dakota

If the recent trend holds, Northern Harrier in North Dakota is projected to rise about 24% by 2029 — from 1.5 in 2024 to a central estimate of 1.8 (95% range 0.95–2.7). A 5-year backtest shows a typical error of ±40.5%, with 80% of held-out values landing inside the 95% band.

+24%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 →
1.8Projected 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 →
0.95–2.795% 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 →
±40.5%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 North Dakota is projected to rise about 24% by 2029 — from 1.5 in 2024 to a central estimate of 1.8 (95% range 0.95–2.7). A 5-year backtest shows a typical error of ±40.5%, with 80% of held-out values landing inside the 95% band.19672029
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 →
20251.80.932.7
20261.80.942.7
20271.80.942.7
20281.80.952.7
20291.80.952.7

Northern Harrier Survey Routes in North Dakota

Routes recording Northern Harrier in North Dakota.
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 →
Bowesmont520141969
Gorham520181968
Solen520242005
Webster420241991
Carson420241988
Kempton320171968
Buchanan320241969
Lark319861969
Zap320241967
Danzig 2320232019
Lakota 2320242010
Forman220241973
Cooperstown220241972
Horsehead Lk220241980
Rolla220241969
Loraine220191982
Tobacco220181968
Denbigh220241968
Roosevelt Pk220191983
Golva220221979
Parshall220131982
Sheyenne Lk220231987
Bowesmont 2220162015
Walcott120231971
Sydney119791967

Northern Harrier Population Trend in Other States

alabamaalaskaarizonaarkansascaliforniacoloradodelawaregeorgiaidahoillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinaohiooklahomaoregonpennsylvaniarhode-islandsouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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