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

Brown-headed Cowbird In Sonoran and Mojave Deserts

All regionsSonoran and Mojave DesertsGeneralists

Brown-headed Cowbird in Sonoran and Mojave Deserts has declined: down 37% on the route-weighted index since 1970.

-37%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 →
76Routes 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 →
56YearsYears 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 Brown-headed Cowbird in Sonoran and Mojave Deserts. See the full index history below.

Brown-headed Cowbird In Sonoran and Mojave Deserts Population Forecast

If the recent trend holds, Brown-headed Cowbird in Sonoran and Mojave Deserts is projected to rise about 67% by 2029 — from 2.4 in 2024 to a central estimate of 4.1 (95% range 0.00–8.3). A 5-year backtest shows a typical error of ±85.4%, with 100% of held-out values landing inside the 95% band.

+67%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 →
4.1Projected 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 →
0.00–8.395% 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 →
±85.4%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, Brown-headed Cowbird in Sonoran and Mojave Deserts is projected to rise about 67% by 2029 — from 2.4 in 2024 to a central estimate of 4.1 (95% range 0.00–8.3). A 5-year backtest shows a typical error of ±85.4%, 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 →
20254.10.008.3
20264.10.008.3
20274.10.008.3
20284.10.008.3
20294.10.008.3

Routes In Sonoran and Mojave Deserts

Routes recording Brown-headed Cowbird 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 →
TronaCALIFORNIA271977
Palo VerdeCALIFORNIA222024
AjoARIZONA162001
Cactus ForestARIZONA152024
Palo VerdeARIZONA122013
PisinimoARIZONA111993
Ash MeadowsNEVADA112023
CimaCALIFORNIA82021
LagunaARIZONA72023
ArabyARIZONA72023
Imperial DamCALIFORNIA72010
Jean LakeNEVADA71991
DatelandARIZONA62024
WickenburgARIZONA62023
FlorenceARIZONA51976
Red RockARIZONA52014
Palo Verde 2ARIZONA52024
Parker DamCALIFORNIA52007
Red Rock 2ARIZONA42024
Willow Beach 2ARIZONA42018
Hope 2ARIZONA42019
Coachella CnCALIFORNIA42000
BrawleyCALIFORNIA42009
WikieupARIZONA32024
QuartzsiteARIZONA32013

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