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

Brown-headed Cowbird In Coastal California

All regionsCoastal CaliforniaGeneralists

Brown-headed Cowbird in Coastal California has increased: up 49% on the route-weighted index since 1970.

+49%Since 1970
116Routes In Region
56Years

Notable Signals

No notable trend signals for Brown-headed Cowbird in Coastal California. See the full index history below.

Forecast

If the recent trend holds, Brown-headed Cowbird in Coastal California is projected to rise about 54% by 2029 — from 5.7 in 2024 to a central estimate of 8.8 (95% range 3.5–14). A 5-year backtest shows a typical error of ±108.8%, with 60% of held-out values landing inside the 95% band.

+54%Change by 2029
8.8Projected 2029 index
3.5–1495% range
±108.8%Backtest error
19682029
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
20258.73.414
20268.73.414
20278.83.414
20288.83.514
20298.83.514

Routes In Coastal California

Routes recording Brown-headed Cowbird in Coastal California.
TiptonCALIFORNIA491997
AtwaterCALIFORNIA332012
CaruthersCALIFORNIA311987
JacksonCALIFORNIA301992
CordovaCALIFORNIA281980
Staten Is.CALIFORNIA282024
Ora LomaCALIFORNIA272024
Red BluffCALIFORNIA232024
GlennCALIFORNIA212023
CollegevilleCALIFORNIA202004
HollisterCALIFORNIA202011
CoyoteCALIFORNIA202024
Big BearCALIFORNIA191986
Yokohl ValCALIFORNIA181997
Collegeville 2CALIFORNIA182023
PenningtonCALIFORNIA172024
White RiverCALIFORNIA171992
TracyCALIFORNIA172009
AthloneCALIFORNIA162007
CopperopolisCALIFORNIA152024
BakersfieldCALIFORNIA142023
VentucopaCALIFORNIA141998
HughsonCALIFORNIA132024
OilfieldsCALIFORNIA102005
Orange CoveCALIFORNIA102016

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