BirdAnalyst
Species · New Mexico · BBS 2025 Release · 1966–2024

Northern Harrier Population Trend in New Mexico

All statesGeneralists

Northern Harrier in New Mexico has collapsed: down 76% on the route-weighted index since 1973.

-76%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 →
29Routes In StateSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
37YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Northern Harrier Trends in New MexicoNotable 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 collapsed in New Mexico: down 76% on the route-weighted index since 1973.

Northern Harrier Population Forecast in New Mexico

If the recent trend holds, Northern Harrier in New Mexico is projected to stay roughly flat through 2028, near 0.05 (95% range 0.00–0.17). A 5-year backtest shows a typical error of ±103.9%, with 80% of held-out values landing inside the 95% band.

n/aChange by 2028TrendPercent 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 →
0.05Projected 2028 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–0.1795% 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 →
±103.9%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 New Mexico is projected to stay roughly flat through 2028, near 0.05 (95% range 0.00–0.17). A 5-year backtest shows a typical error of ±103.9%, with 80% of held-out values landing inside the 95% band.19682028
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 →
20240.060.000.18
20250.060.000.18
20260.060.000.17
20270.060.000.17
20280.050.000.17

Northern Harrier Survey Routes in New Mexico

Routes recording Northern Harrier in New Mexico.
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 →
Farley220072007
Lake Valley220071980
Nageesi120212021
Grenville120151980
Pecos119801980
Wagon Mound119761976
Fence Lake120142014
Correo119821982
Cooley Lake120181968
Floyd120151992
Horse Mtn119711968
Roswell119731971
Caprock120182018
Gage120071977
Jornada120081979
Maxwell120112005
Rodeo120071986
Counselor120092009
Sedan120171999
Rosebud120222003
Clovis120181994
Laborcita120192008
Bitter Lake120231994
Pep120002000
Hobbs120051994

Northern Harrier Population Trend in Other States

alabamaalaskaarizonaarkansascaliforniacoloradodelawaregeorgiaidahoillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamissourimontananebraskanevadanew-hampshirenew-jerseynew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniarhode-islandsouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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