BirdAnalyst
Species · BCR 16 · BBS 2025 Release · 1966–2024

Northern Harrier In Southern Rockies / Colorado Plateau

All regionsSouthern Rockies / Colorado PlateauGeneralists

Northern Harrier in Southern Rockies / Colorado Plateau 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 →
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 →
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 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 58% 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 2029, near 0.06 (95% range 0.00–0.14). A 5-year backtest shows a typical error of ±44.7%, with 100% of held-out values landing inside the 95% band.

n/aChange 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 →
0.06Projected 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 →
0.00–0.1495% 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 →
±44.7%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 2029, near 0.06 (95% range 0.00–0.14). A 5-year backtest shows a typical error of ±44.7%, 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 →
20250.060.000.14
20260.060.000.14
20270.060.000.14
20280.060.000.14
20290.060.000.14

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
Gilson ButteUTAH22000
Canyon RimsUTAH22024
MonticelloUTAH22018
Wellington 3UTAH22022
Lost Cr. ResUTAH22012
BrookhurstWYOMING22006
House RockARIZONA12013
OraibiARIZONA12022
KaibitoARIZONA12009
YampaCOLORADO12015
BufordCOLORADO12016
ParlinCOLORADO12007
DoloresCOLORADO11987
FalfaCOLORADO12007
BlancaCOLORADO11981

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