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

Northern Harrier In Northern Rockies

All regionsNorthern RockiesGeneralists

Northern Harrier in Northern Rockies has held roughly steady: up 2% on the route-weighted index since 1970.

+2%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 →
137Routes 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 →
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 SignalsNotable 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 Northern Harrier in Northern Rockies. See the full index history below.

Forecast

If the recent trend holds, Northern Harrier in Northern Rockies is projected to fall about 29% by 2029 — from 0.55 in 2024 to a central estimate of 0.39 (95% range 0.14–0.65). A 5-year backtest shows a typical error of ±14.3%, with 100% of held-out values landing inside the 95% band.

-29%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 →
0.39Projected 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 →
0.14–0.6595% 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 →
±14.3%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 Northern Rockies is projected to fall about 29% by 2029 — from 0.55 in 2024 to a central estimate of 0.39 (95% range 0.14–0.65). A 5-year backtest shows a typical error of ±14.3%, 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 →
20250.400.150.65
20260.400.140.65
20270.400.140.65
20280.400.140.65
20290.390.140.65

Routes In Northern Rockies

Routes recording Northern Harrier 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 →
Church HillMONTANA72024
E. Bear LakeUTAH62021
Crane CreekIDAHO42016
BeaverheadMONTANA42024
MadrasOREGON42024
Neponset ResUTAH42018
DanielWYOMING41988
RelianceWYOMING42001
Great DivideCOLORADO32024
NaplesIDAHO32024
CabartonIDAHO31994
Sawtooth CtyIDAHO32014
Willow Creek 2MONTANA32024
Wolf CreekMONTANA32019
Threemile WaMONTANA32012
SpartaOREGON31999
WoodruffUTAH32012
Patrick DrawWYOMING31978
FrannieWYOMING32024
FarsonWYOMING32024
Green RiverWYOMING31984
Browns ParkCOLORADO22015
CentervilleIDAHO21982
KalispellMONTANA22024
PolsonMONTANA22024

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