BirdAnalyst
Species · BCR 33 · BBS 2025 Release · 1966–2024

Northern Harrier In Sonoran and Mojave Deserts

All regionsSonoran and Mojave DesertsGeneralists

Northern Harrier in Sonoran and Mojave Deserts has increased: up 49% on the route-weighted index since 1975.

+49%Since 1975TrendPercent 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 →
19Routes 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 →
48YearsYears 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 →

No notable trend signals for Northern Harrier in Sonoran and Mojave Deserts. See the full index history below.

Northern Harrier In Sonoran and Mojave Deserts Population Forecast

If the recent trend holds, Northern Harrier in Sonoran and Mojave Deserts is projected to fall about 24% by 2029 — from 0.13 in 2024 to a central estimate of 0.10 (95% range 0.00–0.25). A 5-year backtest shows a typical error of ±68.9%, with 100% of held-out values landing inside the 95% band.

-24%Change 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 →
0.10Projected 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 →
0.00–0.2595% 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 →
±68.9%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 Sonoran and Mojave Deserts is projected to fall about 24% by 2029 — from 0.13 in 2024 to a central estimate of 0.10 (95% range 0.00–0.25). A 5-year backtest shows a typical error of ±68.9%, 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 →
20250.100.000.25
20260.100.000.25
20270.100.000.25
20280.100.000.25
20290.100.000.25

Routes In Sonoran and Mojave Deserts

Routes recording Northern Harrier in Sonoran and Mojave Deserts.
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 →
CoolidgeARIZONA31981
BrawleyCALIFORNIA32009
Ash MeadowsNEVADA32024
Haiwee ResCALIFORNIA21997
Palo VerdeCALIFORNIA22021
LenwoodCALIFORNIA21995
Coachella CnCALIFORNIA22000
VicksburgARIZONA11987
Cactus ForestARIZONA12012
Calif CityCALIFORNIA11980
GlamisCALIFORNIA11968
Anza BorregoCALIFORNIA11987
Eureka ValCALIFORNIA12016
NilandCALIFORNIA12023
Alamo RiverCALIFORNIA12018
Lone PineCALIFORNIA12024
Death ValleyCALIFORNIA11985
Kelso ValleyCALIFORNIA11984
BeattyNEVADA12021

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