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

Northern Harrier Population Trend in Wyoming

All statesGeneralists

Northern Harrier in Wyoming has edged down: down 19% on the route-weighted index since 1970.

-19%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 →
113Routes 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 WyomingNotable 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 Wyoming. See the full index history below.

Northern Harrier Population Forecast in Wyoming

If the recent trend holds, Northern Harrier in Wyoming is projected to fall about 25% by 2029 — from 0.45 in 2024 to a central estimate of 0.34 (95% range 0.00–0.77). A 5-year backtest shows a typical error of ±17.5%, 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 →
0.34Projected 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 →
0.00–0.7795% 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 →
±17.5%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 Wyoming is projected to fall about 25% by 2029 — from 0.45 in 2024 to a central estimate of 0.34 (95% range 0.00–0.77). A 5-year backtest shows a typical error of ±17.5%, 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 →
20250.360.000.79
20260.350.000.78
20270.350.000.78
20280.340.000.77
20290.340.000.77

Northern Harrier Survey Routes in Wyoming

Routes recording Northern Harrier in Wyoming.
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 →
Sussex420161992
Daniel419881980
Shawnee420031991
Reliance420011977
Gvnt Valley420192000
Patrick Draw319781973
Frannie320241999
Farson320241995
Green River319841977
Clarkelen219781968
Natrona219921968
Brookhurst220061968
Savery219891989
Dayton220241981
Schoonover220231989
Arvada220081982
Gebo220241992
Highlight219821982
Raven220241992
Bairoil220221988
Meadowdale219921992
Lingle220241989
Elk Horn 2220242022
Welch220181978
Flamin Gorge220171988

Northern Harrier Population Trend in Other States

alabamaalaskaarizonaarkansascaliforniacoloradodelawaregeorgiaidahoillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniarhode-islandsouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsin

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