BirdAnalyst
Species · BCR 35 · BBS 2025 Release · 1966–2024

Northern Harrier In Chihuahuan Desert

All regionsChihuahuan DesertGeneralists

Northern Harrier in Chihuahuan Desert 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 →
15Routes 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 →
32YearsYears 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 collapsed in Chihuahuan Desert: down 76% on the route-weighted index since 1973.

Northern Harrier In Chihuahuan Desert Population Forecast

If the recent trend holds, Northern Harrier in Chihuahuan Desert is projected to stay roughly flat through 2028, near 0.06 (95% range 0.00–0.20). A 5-year backtest shows a typical error of ±42.4%, with 100% 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 →
0.06Projected 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 →
0.00–0.2095% 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 →
±42.4%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 Chihuahuan Desert is projected to stay roughly flat through 2028, near 0.06 (95% range 0.00–0.20). A 5-year backtest shows a typical error of ±42.4%, with 100% of held-out values landing inside the 95% band.19702028
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 →
20240.060.000.21
20250.060.000.21
20260.060.000.21
20270.060.000.20
20280.060.000.20

Routes In Chihuahuan Desert

Routes recording Northern Harrier in Chihuahuan Desert.
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 →
Lake ValleyNEW-MEXICO22007
CornudasTEXAS21973
SlaughterTEXAS21975
RoswellNEW-MEXICO11973
GageNEW-MEXICO12007
JornadaNEW-MEXICO12008
RodeoNEW-MEXICO12007
LaborcitaNEW-MEXICO12019
Bitter LakeNEW-MEXICO12023
ColumbusNEW-MEXICO12009
EscondidaNEW-MEXICO12019
Sunshine WllNEW-MEXICO12009
AltudaTEXAS12005
ToyahvaleTEXAS12007
MarathonTEXAS12005

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