BirdAnalyst
Species · BCR 16 · BBS 2026 Release · 1966–2025

Northern Harrier In Southern Rockies / Colorado Plateau

All regionsSouthern Rockies / Colorado PlateauBirds of prey

Northern Harrier in Southern Rockies / Colorado Plateau has fallen sharply: down 55% on the route-weighted index since 1970.

-55%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 →
88Routes 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 →
53YearsYears 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 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 →

Northern Harrier has fallen sharply in Southern Rockies / Colorado Plateau: down 55% on the route-weighted index since 1970.

Northern Harrier In Southern Rockies / Colorado Plateau Population Forecast

If the recent trend holds, Northern Harrier in Southern Rockies / Colorado Plateau is projected to stay roughly flat through 2030, near 0.06 (95% range 0.00–0.14). A 5-year backtest shows a typical error of ±51%, with 100% of held-out values landing inside the 95% band.

n/aChange 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 →
0.06Projected 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 →
0.00–0.1495% 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 →
±51%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 Southern Rockies / Colorado Plateau is projected to stay roughly flat through 2030, near 0.06 (95% range 0.00–0.14). A 5-year backtest shows a typical error of ±51%, 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 →
20260.060.000.14
20270.060.000.14
20280.060.000.14
20290.060.000.14
20300.060.000.14

Routes In Southern Rockies / Colorado Plateau

Routes recording Northern Harrier in Southern Rockies / Colorado Plateau.
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 →
ToroweapARIZONA62006
MoscaCOLORADO32005
Hill CreekUTAH31995
Gilson Butte 2UTAH32011
Douglas PassCOLORADO22023
MoffatCOLORADO22015
Pleasant ViewCOLORADO22021
San LuisCOLORADO22009
MesitaCOLORADO22008
HanksvilleUTAH21995
Ant Flat-Ogden CanUTAH22025
Gilson ButteUTAH22000
Canyon RimsUTAH22024
MonticelloUTAH22018
Wellington 3UTAH22022
Lost Cr. ResUTAH22012
BrookhurstWYOMING22006
House RockARIZONA12013
OraibiARIZONA12022
KaibitoARIZONA12009
YampaCOLORADO12015
BufordCOLORADO12016
ParlinCOLORADO12007
DoloresCOLORADO11987
FalfaCOLORADO12007

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