BirdAnalyst
Species · BCR 10 · BBS 2026 Release · 1966–2025

Northern Harrier In Northern Rockies

All regionsNorthern RockiesBirds of prey

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 →
138Routes 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 →
57YearsYears 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.

Northern Harrier In Northern Rockies Population Forecast

If the recent trend holds, Northern Harrier in Northern Rockies is projected to stay roughly flat through 2030, near 0.39 (95% range 0.14–0.64). A 5-year backtest shows a typical error of ±9.6%, with 100% of held-out values landing inside the 95% band.

-4%Change by 2030TrendPercent 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 2030 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.14–0.6495% 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 →
±9.6%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 stay roughly flat through 2030, near 0.39 (95% range 0.14–0.64). A 5-year backtest shows a typical error of ±9.6%, with 100% of held-out values landing inside the 95% band.19682030
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 →
20260.400.150.64
20270.390.140.64
20280.390.140.64
20290.390.140.64
20300.390.140.64

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 →
Great DivideCOLORADO52025
Red RockMONTANA52025
Crane CreekIDAHO42016
Neponset ResUTAH42018
DanielWYOMING41988
PathfinderWYOMING42025
RelianceWYOMING42001
NaplesIDAHO32024
CabartonIDAHO31994
Sawtooth CtyIDAHO32014
LimaMONTANA32025
Wolf CreekMONTANA32019
Threemile WaMONTANA32012
SpartaOREGON32025
WoodruffUTAH32012
Patrick DrawWYOMING31978
FarsonWYOMING32025
Green RiverWYOMING31984
Browns ParkCOLORADO22025
CentervilleIDAHO21982
Sawtooth City 2IDAHO22025
KalispellMONTANA22024
LaurelMONTANA22017
Pablo Res.MONTANA22025
Wise RiverMONTANA22016

Source: USGS North American Breeding Bird Survey, retrieved 2026-08-14.