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

Northern Harrier Population Trend in Alaska

All statesGeneralists

Northern Harrier in Alaska has fallen sharply: down 66% on the route-weighted index since 1986.

-66%Since 1986TrendPercent 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 →
51Routes 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 →
37YearsYears 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 AlaskaNotable 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 declinecomputed 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 fallen sharply in Alaska: down 66% on the route-weighted index since 1986.

Northern Harrier Population Forecast in Alaska

If the recent trend holds, Northern Harrier in Alaska is projected to fall about 12% by 2029 — from 0.06 in 2024 to a central estimate of 0.05 (95% range 0.00–0.18). A 5-year backtest shows a typical error of ±61.8%, with 100% of held-out values landing inside the 95% band.

-12%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 →
0.05Projected 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 →
0.00–0.1895% 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 →
±61.8%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 Alaska is projected to fall about 12% by 2029 — from 0.06 in 2024 to a central estimate of 0.05 (95% range 0.00–0.18). A 5-year backtest shows a typical error of ±61.8%, with 100% of held-out values landing inside the 95% band.19822029
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 →
20250.060.000.19
20260.060.000.19
20270.060.000.19
20280.050.000.19
20290.050.000.18

Northern Harrier Survey Routes in Alaska

Routes recording Northern Harrier in Alaska.
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 →
Salmon Lake320171996
Chistochina220232009
Cantwell219981998
Teller220172017
Cordova220091983
Red Dog220232022
Lake Louise220082008
Mitkof Isle220022002
Eagle120142012
Chatanika R120072007
Livengood120112011
Paxson Lake119971995
Slana120242024
Kuskulana120182018
Maclaren120111982
Monahan120211983
Toklat120191982
Burma Road119981998
Cape Nome120112006
Caribou Mtn.120232005
Coldfoot120112011
Council120181997
Donelly Dome120242000
Unalakleet River119971997
Galbraith L.120211994

Northern Harrier Population Trend in Other States

alabamaarizonaarkansascaliforniacoloradodelawaregeorgiaidahoillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniarhode-islandsouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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