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

Brewer's Sparrow In Coastal California

All regionsCoastal CaliforniaGeneralists

Brewer's Sparrow in Coastal California has collapsed: down 94% on the route-weighted index since 1971.

-94%Since 1971
10Routes In Region
40Years

Notable Signals

long arc declinecomputed index

Brewer's Sparrow has collapsed in Coastal California: down 94% on the route-weighted index since 1971.

Forecast

If the recent trend holds, Brewer's Sparrow in Coastal California is projected to fall about 100% by 2024 — from 0.06 in 2019 to a central estimate of 0.00 (95% range 0.00–0.49). A 5-year backtest shows a typical error of ±66.3%, with 100% of held-out values landing inside the 95% band.

-100%Change by 2024
0.00Projected 2024 index
0.00–0.4995% range
±66.3%Backtest error
19692024
Projection of the recent trend (dashed) with 80/95% bands — a projection, not a prediction. Habitat, climate, and land use are not modeled.
YearProjected index95% low95% high
20200.040.000.54
20210.030.000.52
20220.020.000.51
20230.010.000.50
20240.000.000.49

Routes In Coastal California

Routes recording Brewer's Sparrow in Coastal California.
VentucopaCALIFORNIA82001
Big BearCALIFORNIA71986
Lockwood ValCALIFORNIA32019
Lake HemetCALIFORNIA21974
Cp. PendletonCALIFORNIA21980
Mt PinosCALIFORNIA11984
Lake SuccessCALIFORNIA11972
Mesa GrandeCALIFORNIA11975
ValyermoCALIFORNIA11996
Green ValleyCALIFORNIA11997

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