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

Bell's Vireo In Sonoran and Mojave Deserts

All regionsSonoran and Mojave DesertsForest birds

Bell's Vireo in Sonoran and Mojave Deserts has risen sharply: up 58% on the route-weighted index since 1970.

+58%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 →
29Routes 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 →
45YearsYears 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 increasecomputed 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 →

Bell's Vireo has risen sharply in Sonoran and Mojave Deserts: up 58% on the route-weighted index since 1970.

Bell's Vireo In Sonoran and Mojave Deserts Population Forecast

If the recent trend holds, Bell's Vireo in Sonoran and Mojave Deserts is projected to rise about 523% by 2029 — from 0.13 in 2024 to a central estimate of 0.83 (95% range 0.21–1.5). A 5-year backtest shows a typical error of ±336.6%, with 40% of held-out values landing inside the 95% band.

+523%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 →
0.83Projected 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 →
0.21–1.595% 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 →
±336.6%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, Bell's Vireo in Sonoran and Mojave Deserts is projected to rise about 523% by 2029 — from 0.13 in 2024 to a central estimate of 0.83 (95% range 0.21–1.5). A 5-year backtest shows a typical error of ±336.6%, with 40% 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 →
20250.780.151.4
20260.790.171.4
20270.800.181.4
20280.820.191.4
20290.830.211.5

Routes In Sonoran and Mojave Deserts

Routes recording Bell's Vireo 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 →
Cutter 2ARIZONA172018
PisinimoARIZONA101993
AjoARIZONA32001
Red RockARIZONA32014
Casa GrandeARIZONA32023
Ajo 2ARIZONA32017
TecopaCALIFORNIA32023
FlorenceARIZONA21988
Red Rock 2ARIZONA22024
OatmanARIZONA11994
New RiverARIZONA12009
LagunaARIZONA12006
DatelandARIZONA12016
CoolidgeARIZONA11974
LukevilleARIZONA11979
RivieraARIZONA12018
Alamo Res.ARIZONA12018
Palo VerdeARIZONA12010
Cabeza PrietARIZONA12019
Cactus ForestARIZONA12019
Organ PipeARIZONA12021
Palo Verde 2ARIZONA12021
Bates WellARIZONA12022
WildroseCALIFORNIA12004
Anza BorregoCALIFORNIA12024

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