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

Hermit Thrush In Coastal California

All regionsCoastal CaliforniaForest birds

Hermit Thrush in Coastal California has surged: up 186% on the route-weighted index since 1973.

+186%Since 1973TrendPercent 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 →
28Routes 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 →
54YearsYears 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 →

Hermit Thrush has surged in Coastal California: up 186% on the route-weighted index since 1973.

Hermit Thrush In Coastal California Population Forecast

If the recent trend holds, Hermit Thrush in Coastal California is projected to rise about 42% by 2030 — from 0.66 in 2025 to a central estimate of 0.93 (95% range 0.35–1.5). A 5-year backtest shows a typical error of ±103.9%, with 60% of held-out values landing inside the 95% band.

+42%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 →
0.93Projected 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 →
0.35–1.595% 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 →
±103.9%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, Hermit Thrush in Coastal California is projected to rise about 42% by 2030 — from 0.66 in 2025 to a central estimate of 0.93 (95% range 0.35–1.5). A 5-year backtest shows a typical error of ±103.9%, with 60% 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 →
20260.890.321.5
20270.900.331.5
20280.910.341.5
20290.920.341.5
20300.930.351.5

Routes In Coastal California

Routes recording Hermit Thrush 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 →
FairfaxCALIFORNIA192024
Waterman GapCALIFORNIA142025
PescaderoCALIFORNIA112025
JofeganCALIFORNIA62009
CalpellaCALIFORNIA51986
Morro BayCALIFORNIA51975
Mark WestCALIFORNIA51975
JacksonCALIFORNIA31977
MoragaCALIFORNIA31988
Point ReyesCALIFORNIA22023
Mt LagunaCALIFORNIA21977
Lake CachumaCALIFORNIA22003
ParkfieldCALIFORNIA11974
Santa YnezCALIFORNIA12002
Big BearCALIFORNIA11986
CohassetCALIFORNIA12023
Sawmill MtnCALIFORNIA11977
ValyermoCALIFORNIA11989
FallsvaleCALIFORNIA11975
Elsinore MtnCALIFORNIA11974
AdelaidaCALIFORNIA11977
TehamaCALIFORNIA11988
CoyoteCALIFORNIA11977
Glen EllenCALIFORNIA11992
Glen Ellen 2CALIFORNIA12016

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