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.

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.