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

Orange-crowned Warbler In Coastal California

All regionsCoastal CaliforniaForest birds

Orange-crowned Warbler in Coastal California has surged: up 143% on the route-weighted index since 1970.

+143%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 →
87Routes 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 →

Orange-crowned Warbler has surged in Coastal California: up 143% on the route-weighted index since 1970.

Orange-crowned Warbler In Coastal California Population Forecast

If the recent trend holds, Orange-crowned Warbler in Coastal California is projected to rise about 73% by 2030 — from 3.2 in 2025 to a central estimate of 5.5 (95% range 2.9–8.1). A 5-year backtest shows a typical error of ±87%, with 40% of held-out values landing inside the 95% band.

+73%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 →
5.5Projected 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 →
2.9–8.195% 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 →
±87%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, Orange-crowned Warbler in Coastal California is projected to rise about 73% by 2030 — from 3.2 in 2025 to a central estimate of 5.5 (95% range 2.9–8.1). A 5-year backtest shows a typical error of ±87%, with 40% 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 →
20265.32.77.9
20275.42.87.9
20285.42.88.0
20295.42.88.0
20305.52.98.1

Routes In Coastal California

Routes recording Orange-crowned Warbler 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 →
RumseyCALIFORNIA452008
Santa Cruz ICALIFORNIA421988
Harbor Lake 2CALIFORNIA412024
Glen EllenCALIFORNIA302004
S CatalinaCALIFORNIA232025
Carmel ValCALIFORNIA202025
Bartlett SpsCALIFORNIA192018
CohassetCALIFORNIA122025
PowayCALIFORNIA121980
FolsomCALIFORNIA122025
FairfaxCALIFORNIA112019
AdelaidaCALIFORNIA112015
Elsinore MtnCALIFORNIA102024
Jofegan 2CALIFORNIA102025
Point ReyesCALIFORNIA92025
Gold HillCALIFORNIA82025
Waterman GapCALIFORNIA82025
StonyfordCALIFORNIA82018
Lake SuccessCALIFORNIA71996
PescaderoCALIFORNIA72025
San YsidroCALIFORNIA62019
AuburnCALIFORNIA61979
PolomaCALIFORNIA62024
ColmaCALIFORNIA51972
Lake BerryessaCALIFORNIA52024

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