BirdAnalyst
Species · BCR 32 · BBS 2025 Release · 1966–2024

Nashville Warbler In Coastal California

All regionsCoastal CaliforniaForest birds

Nashville Warbler in Coastal California has risen sharply: up 67% on the route-weighted index since 1971.

+67%Since 1971TrendPercent 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 →
22Routes 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 →
55YearsYears 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 →

Nashville Warbler has risen sharply in Coastal California: up 67% on the route-weighted index since 1971.

Nashville Warbler In Coastal California Population Forecast

If the recent trend holds, Nashville Warbler in Coastal California is projected to rise about 185% by 2029 — from 0.11 in 2024 to a central estimate of 0.30 (95% range 0.00–0.82). A 5-year backtest shows a typical error of ±101.2%, with 100% of held-out values landing inside the 95% band.

+185%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 →
0.30Projected 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 →
0.00–0.8295% 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 →
±101.2%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, Nashville Warbler in Coastal California is projected to rise about 185% by 2029 — from 0.11 in 2024 to a central estimate of 0.30 (95% range 0.00–0.82). A 5-year backtest shows a typical error of ±101.2%, with 100% of held-out values landing inside the 95% band.19692029
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 →
20250.320.000.83
20260.310.000.83
20270.310.000.83
20280.310.000.82
20290.300.000.82

Routes In Coastal California

Routes recording Nashville 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 →
TomheadCALIFORNIA102011
Lake SuccessCALIFORNIA71996
White RiverCALIFORNIA71992
Bartlett SpsCALIFORNIA72018
Red BluffCALIFORNIA41983
CohassetCALIFORNIA42024
Yokohl ValCALIFORNIA31997
ValyermoCALIFORNIA31996
Cal Hot SpgsCALIFORNIA32017
Hough SpringsCALIFORNIA32007
FallsvaleCALIFORNIA21975
TehamaCALIFORNIA22022
StonyfordCALIFORNIA22018
CalpellaCALIFORNIA11984
Foster ParkCALIFORNIA11977
Mt PinosCALIFORNIA11985
Point ReyesCALIFORNIA11975
Sawmill MtnCALIFORNIA12013
Carmel ValCALIFORNIA12006
SangerCALIFORNIA12024
Green ValleyCALIFORNIA11975
WoodlandsCALIFORNIA12019

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