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

Warbling Vireo In Coastal California

All regionsCoastal CaliforniaForest birds

Warbling Vireo in Coastal California has surged: up 113% on the route-weighted index since 1970.

+113%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 →
79Routes 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 →
57YearsYears 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 →

Warbling Vireo has surged in Coastal California: up 113% on the route-weighted index since 1970.

Warbling Vireo In Coastal California Population Forecast

If the recent trend holds, Warbling Vireo in Coastal California is projected to rise about 47% by 2030 — from 3.4 in 2025 to a central estimate of 5.1 (95% range 3.2–6.9). A 5-year backtest shows a typical error of ±62.8%, with 0% of held-out values landing inside the 95% band.

+47%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 →
5.1Projected 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 →
3.2–6.995% 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 →
±62.8%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, Warbling Vireo in Coastal California is projected to rise about 47% by 2030 — from 3.4 in 2025 to a central estimate of 5.1 (95% range 3.2–6.9). A 5-year backtest shows a typical error of ±62.8%, with 0% of held-out values landing inside the 95% band.19682030
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 →
20264.93.16.8
20275.03.16.8
20285.03.26.8
20295.03.26.9
20305.13.26.9

Routes In Coastal California

Routes recording Warbling 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 →
Waterman GapCALIFORNIA372025
Point ReyesCALIFORNIA302025
PescaderoCALIFORNIA232025
Carmel ValCALIFORNIA212025
FairfaxCALIFORNIA162024
StonyfordCALIFORNIA102018
OnoCALIFORNIA82011
LockwoodCALIFORNIA82025
CalpellaCALIFORNIA71986
Glen EllenCALIFORNIA72004
Santa YnezCALIFORNIA52019
Mt BaldyCALIFORNIA52024
Bartlett SpsCALIFORNIA52017
Angelus OaksCALIFORNIA52017
SisquocCALIFORNIA42014
AdelaidaCALIFORNIA41999
Gold HillCALIFORNIA42025
Tres Pinos 2CALIFORNIA42010
RumseyCALIFORNIA32008
AnzaCALIFORNIA31981
SangerCALIFORNIA32021
Elizabeth LkCALIFORNIA31985
Yolla BollyCALIFORNIA32018
Glen Ellen 3CALIFORNIA32025
ColmaCALIFORNIA21971

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