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

Northern Harrier Population Trend in Utah

All statesGeneralists

Northern Harrier in Utah has declined: down 30% on the route-weighted index since 1970.

-30%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 →
82Routes 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 →
54YearsYears 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 UtahNotable 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 Utah. See the full index history below.

Northern Harrier Population Forecast in Utah

If the recent trend holds, Northern Harrier in Utah is projected to fall about 27% by 2029 — from 0.56 in 2024 to a central estimate of 0.41 (95% range 0.00–1.4). A 5-year backtest shows a typical error of ±21.2%, with 100% of held-out values landing inside the 95% band.

-27%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 →
0.41Projected 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 →
0.00–1.495% 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 →
±21.2%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 Utah is projected to fall about 27% by 2029 — from 0.56 in 2024 to a central estimate of 0.41 (95% range 0.00–1.4). A 5-year backtest shows a typical error of ±21.2%, 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 →
20250.450.001.4
20260.440.001.4
20270.430.001.4
20280.420.001.4
20290.410.001.4

Northern Harrier Survey Routes in Utah

Routes recording Northern Harrier in Utah.
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 →
Snowville1420241999
Promontory920241969
E. Bear Lake620211996
Johnson Can420241987
Goose Creek Mtn.420092005
Neponset Res420181995
Timpie Spg320031978
Hill Creek319951994
Peplin Mountain320231999
Gilson Butte 2320112006
Woodruff320122009
Wellington 3220222019
Wendover220111969
Goshen220231968
Hanksville219951992
Lynn220231982
Wah Wah220191999
Callao220211992
Gilson Butte220001993
Grantsville220212001
Jericho Junction220222006
Pine Creek220232001
Canyon Rims220242013
Newcastle220062006
Monticello220182000

Northern Harrier Population Trend in Other States

alabamaalaskaarizonaarkansascaliforniacoloradodelawaregeorgiaidahoillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniarhode-islandsouth-dakotatennesseetexasvermontvirginiawashingtonwest-virginiawisconsinwyoming

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