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

Ferruginous Hawk Population Trend in Montana

All statesGeneralists

Ferruginous Hawk in Montana has surged: up 238% on the route-weighted index since 1973.

+238%Since 1973TrendPercent 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 →
61Routes 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 →
53YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Ferruginous Hawk Trends in MontanaNotable 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 →

Ferruginous Hawk has surged in Montana: up 238% on the route-weighted index since 1973.

Ferruginous Hawk Population Forecast in Montana

If the recent trend holds, Ferruginous Hawk in Montana is projected to rise about 22% by 2029 — from 0.53 in 2024 to a central estimate of 0.65 (95% range 0.39–0.90). A 5-year backtest shows a typical error of ±27.7%, with 100% of held-out values landing inside the 95% band.

+22%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 →
0.65Projected 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 →
0.39–0.9095% 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 →
±27.7%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, Ferruginous Hawk in Montana is projected to rise about 22% by 2029 — from 0.53 in 2024 to a central estimate of 0.65 (95% range 0.39–0.90). A 5-year backtest shows a typical error of ±27.7%, 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 →
20250.610.350.87
20260.620.360.88
20270.630.370.89
20280.640.380.89
20290.650.390.90

Ferruginous Hawk Survey Routes in Montana

Routes recording Ferruginous Hawk in Montana.
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 →
Whitlash1020242009
St. Mary 2920242009
Hay Lake720221988
Malta620241988
Jordan South520212016
Powderville320241968
Glentana320242017
Coleman Coulee320212018
St Mary220081977
Virgelle220241979
Harlem220211980
Oswego220241983
Glen220232002
Bull Mtn.220162016
Augusta219861977
Brusett220172017
Shawmut220231987
Webster219921982
Beaverhead220241973
Gildford220192019
Sun River220182018
Miles City220212021
Brunzell Slough220242018
Lima220232023
Sunburst120071991

Ferruginous Hawk Population Trend in Other States

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