BirdAnalyst
Species · BCR 32 · BBS 2026 Release · 1966–2025

Bell's Vireo In Coastal California

All regionsCoastal CaliforniaForest birds

Bell's Vireo in Coastal California has surged: up 693% on the route-weighted index since 1976.

+693%Since 1976TrendPercent 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 →
13Routes 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 →
19YearsYears 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 Bell's Vireo in Coastal California. See the full index history below.

Bell's Vireo In Coastal California Population Forecast

If the recent trend holds, Bell's Vireo in Coastal California is projected to fall about 53% by 2030 — from 0.26 in 2025 to a central estimate of 0.12 (95% range 0.00–0.28). A 5-year backtest shows a typical error of ±75.1%, with 20% of held-out values landing inside the 95% band.

-53%Change by 2030TrendPercent 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 →
0.12Projected 2030 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–0.2895% 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 →
±75.1%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 Coastal California is projected to fall about 53% by 2030 — from 0.26 in 2025 to a central estimate of 0.12 (95% range 0.00–0.28). A 5-year backtest shows a typical error of ±75.1%, with 20% of held-out values landing inside the 95% band.19712030
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 →
20260.110.000.27
20270.120.000.27
20280.120.000.28
20290.120.000.28
20300.120.000.28

Routes In Coastal California

Routes recording Bell's Vireo in Coastal California.
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 →
Jofegan 2CALIFORNIA102025
San YsidroCALIFORNIA52019
Cp. PendletonCALIFORNIA22003
MorenoCALIFORNIA12012
Oak GroveCALIFORNIA12018
CoalingaCALIFORNIA11976
Orange CoveCALIFORNIA11997
PowayCALIFORNIA11979
Mesa GrandeCALIFORNIA12010
Cuyamaca PkCALIFORNIA11971
CrestonCALIFORNIA11976
AtwaterCALIFORNIA12012
JofeganCALIFORNIA12022

Source: USGS North American Breeding Bird Survey, retrieved 2026-08-14.