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

Chipping Sparrow In Coastal California

All regionsCoastal CaliforniaForest birds

Chipping Sparrow in Coastal California has fallen sharply: down 71% on the route-weighted index since 1970.

-71%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 →
77Routes 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 declinecomputed 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 →

Chipping Sparrow has fallen sharply in Coastal California: down 71% on the route-weighted index since 1970.

Chipping Sparrow In Coastal California Population Forecast

If the recent trend holds, Chipping Sparrow in Coastal California is projected to fall about 78% by 2030 — from 1.1 in 2025 to a central estimate of 0.25 (95% range 0.00–1.7). A 5-year backtest shows a typical error of ±34.8%, with 100% of held-out values landing inside the 95% band.

-78%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 →
0.25Projected 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 →
0.00–1.795% 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 →
±34.8%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, Chipping Sparrow in Coastal California is projected to fall about 78% by 2030 — from 1.1 in 2025 to a central estimate of 0.25 (95% range 0.00–1.7). A 5-year backtest shows a typical error of ±34.8%, with 100% 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 →
20260.400.001.8
20270.360.001.8
20280.320.001.7
20290.280.001.7
20300.250.001.7

Routes In Coastal California

Routes recording Chipping Sparrow 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 →
Santa Cruz ICALIFORNIA571988
S CatalinaCALIFORNIA252025
White RiverCALIFORNIA101992
CohassetCALIFORNIA92025
Big BearCALIFORNIA81986
WoodlandsCALIFORNIA82024
Cp. PendletonCALIFORNIA72004
San Benito Mtn.CALIFORNIA62005
CalpellaCALIFORNIA51982
Tres PinosCALIFORNIA51994
AthloneCALIFORNIA51977
Cleveland NfCALIFORNIA51995
StonyfordCALIFORNIA52018
Carmel ValCALIFORNIA42025
Mt LagunaCALIFORNIA41987
JofeganCALIFORNIA42018
Mt PinosCALIFORNIA32004
Oak GroveCALIFORNIA32003
FolsomCALIFORNIA32025
El ToroCALIFORNIA31977
Lockwood ValCALIFORNIA32017
Green ValleyCALIFORNIA32023
Gold HillCALIFORNIA32023
TehamaCALIFORNIA32019
Yokohl ValCALIFORNIA21997

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