BirdAnalyst
Species · BBS 2025 Release · 1966–2024

Ferruginous Hawk

AccipitridaeBirds of preyButeo regalis

Ferruginous Hawk has surged: up 491% on the route-weighted index since 1969.

+491%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 →
515RoutesSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
57Years SurveyedYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

About the Ferruginous Hawk

The Ferruginous Hawk (Buteo regalis) is a North American member of the Hawks, Eagles & Kites (Accipitridae). In this analysis it is grouped with the birds of prey.

Size
17.5–39.5 in long (45–100 cm) — a medium to large raptor (typical for the family)
Habitat
Open country, woodlands, cliffs and wetlands, hunting from the air or a high perch.
Diet
Live prey — small mammals, birds, reptiles, fish and large insects (carrion for vultures).
Range
Recorded on 515 Breeding Bird Survey routes across 17 states, most concentrated in the Great Basin.
Family
Accipitridae · Birds of prey

Notable Ferruginous Hawk TrendsNotable 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 Ferruginous Hawk. See the full index history below.

Ferruginous Hawk Population Forecast

If the recent trend holds, Ferruginous Hawk is projected to rise about 21% by 2029 — from 0.07 in 2024 to a central estimate of 0.08 (95% range 0.06–0.11). A 5-year backtest shows a typical error of ±31.7%, with 80% of held-out values landing inside the 95% band.

+21%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 →
0.08Projected 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 →
0.06–0.1195% 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 →
±31.7%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 is projected to rise about 21% by 2029 — from 0.07 in 2024 to a central estimate of 0.08 (95% range 0.06–0.11). A 5-year backtest shows a typical error of ±31.7%, 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 →
20250.080.050.10
20260.080.050.10
20270.080.050.10
20280.080.050.11
20290.080.060.11

Where the Ferruginous Hawk Is Detected

BBS routes recording Ferruginous Hawk, sized by most recent count.

Ferruginous Hawk Population Trend by State

Ferruginous Hawk population trend by state.
TrendPercent 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 →Baseline yearThe first year of the smoothed window the trend is measured from. An earlier baseline means a longer record stands behind the number.Full methodology →Survey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
Arizonainsufficient datan/a5
Californiainsufficient datan/a4
Colorado-58%197067
Idaho+675%197726
Kansas+49%197416
Montana+238%197361
Nebraska-10%198117
Nevada+35%197022
New Mexico-64%197931
North Dakota+4%196935
Oklahoma+4%19757
Oregon+65%197333
South Dakota+616%197332
Texas-60%19758
Utah-60%197944
Washington-64%198213
Wyoming-41%197094

Ferruginous Hawk Population Trend by Region

Bird Conservation Regions are the ecological unit for trends.

Ferruginous Hawk population trend by Bird Conservation Region.
TrendPercent 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 →Baseline yearThe first year of the smoothed window the trend is measured from. An earlier baseline means a longer record stands behind the number.Full methodology →Survey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
Great Basin+315%1970118
Northern Rockies+213%197382
Prairie Potholes+448%196949
Southern Rockies / Colorado Plateau+55%197446
Badlands and Prairies+60%197098
Shortgrass Prairie+9%197096
Central Mixed Grass Prairie-9%197420

Ferruginous Hawk Conservation Status

Our route-weighted index shows it up about 491% since 1969.

Source: USGS North American Breeding Bird Survey, retrieved 2026-05-22. Trend is a route-weighted relative-abundance index, not an absolute population.