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

Ferruginous Hawk Population Trend in Colorado

All statesGeneralists

Ferruginous Hawk in Colorado has fallen sharply: down 58% on the route-weighted index since 1970.

-58%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 →
67Routes 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 Ferruginous Hawk Trends in ColoradoNotable 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 →

Ferruginous Hawk has fallen sharply in Colorado: down 58% on the route-weighted index since 1970.

Ferruginous Hawk Population Forecast in Colorado

If the recent trend holds, Ferruginous Hawk in Colorado is projected to rise about 99% by 2029 — from 0.11 in 2024 to a central estimate of 0.23 (95% range 0.00–0.53). A 5-year backtest shows a typical error of ±89.8%, with 100% of held-out values landing inside the 95% band.

+99%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 →
0.23Projected 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 →
0.00–0.5395% 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 →
±89.8%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, Ferruginous Hawk in Colorado is projected to rise about 99% by 2029 — from 0.11 in 2024 to a central estimate of 0.23 (95% range 0.00–0.53). A 5-year backtest shows a typical error of ±89.8%, 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 →
20250.230.000.54
20260.230.000.54
20270.230.000.53
20280.230.000.53
20290.230.000.53

Ferruginous Hawk Survey Routes in Colorado

Routes recording Ferruginous Hawk in Colorado.
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 →
Hudson819991993
Pinneo420191981
Blanca319861981
Mica Butte319811968
Gordon Creek320051997
Crowley320241989
Nunn320181995
Como320232023
Stoneham320211994
Prospect Val319931993
Last Chance 2320222022
Maybell220181996
Arsenal220131992
Lamar220171975
Gilpin220241972
Doyle Bridge 2220232006
Cheyenne220221990
Antonito220012001
Pritchett220171995
Mosca220242009
Great Divide120222016
Yampa120102010
Briggsdale120231969
Fleming120151999
Rockport120231994

Ferruginous Hawk Population Trend in Other States

arizonacaliforniaidahokansasmontananebraskanevadanew-mexiconorth-dakotaoklahomaoregonsouth-dakotatexasutahwashingtonwyoming

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