BirdAnalyst
Species · BCR 10 · BBS 2025 Release · 1966–2024

Ferruginous Hawk In Northern Rockies

All regionsNorthern RockiesGeneralists

Ferruginous Hawk in Northern Rockies has surged: up 213% on the route-weighted index since 1973.

+213%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 →
82Routes In RegionSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
52YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable SignalsNotable 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 Northern Rockies: up 213% on the route-weighted index since 1973.

Forecast

If the recent trend holds, Ferruginous Hawk in Northern Rockies is projected to fall about 19% by 2029 — from 0.23 in 2024 to a central estimate of 0.18 (95% range 0.05–0.32). A 5-year backtest shows a typical error of ±21.4%, with 100% of held-out values landing inside the 95% band.

-19%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 →
0.18Projected 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 →
0.05–0.3295% 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 →
±21.4%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 Northern Rockies is projected to fall about 19% by 2029 — from 0.23 in 2024 to a central estimate of 0.18 (95% range 0.05–0.32). A 5-year backtest shows a typical error of ±21.4%, 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 →
20250.180.050.31
20260.180.050.31
20270.180.050.32
20280.180.050.32
20290.180.050.32

Routes In Northern Rockies

Routes recording Ferruginous Hawk in Northern Rockies.
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 →
St. Mary 2MONTANA92024
ShirleyWYOMING52024
FarsonWYOMING42005
BoulderWYOMING32024
Gas HillsWYOMING31993
PathfinderWYOMING32022
CarterWYOMING32016
Carter 2WYOMING32023
MaybellCOLORADO22018
St MaryMONTANA22008
AugustaMONTANA21986
BeaverheadMONTANA22024
LimaMONTANA22023
GlenMONTANA22023
Brunzell SloughMONTANA22024
BridgeportOREGON22013
Neponset ResUTAH22018
ErvayWYOMING22024
MckinnonWYOMING21970
CrowheartWYOMING22008
ArmintoWYOMING22019
SweetwaterWYOMING22009
LamontWYOMING22024
Green RiverWYOMING21982
RelianceWYOMING22018

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