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

Northern Rough-winged Swallow In Coastal California

All regionsCoastal CaliforniaAerial insectivores

Northern Rough-winged Swallow in Coastal California has fallen sharply: down 65% on the route-weighted index since 1970.

-65%Since 1970
105Routes In Region
56Years

Notable Signals

long arc declinecomputed index

Northern Rough-winged Swallow has fallen sharply in Coastal California: down 65% on the route-weighted index since 1970.

Forecast

If the recent trend holds, Northern Rough-winged Swallow in Coastal California is projected to fall about 20% by 2029 — from 1.0 in 2024 to a central estimate of 0.84 (95% range 0.00–2.7). A 5-year backtest shows a typical error of ±47.5%, with 100% of held-out values landing inside the 95% band.

-20%Change by 2029
0.84Projected 2029 index
0.00–2.795% range
±47.5%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
20250.950.002.8
20260.920.002.8
20270.890.002.8
20280.870.002.8
20290.840.002.7

Routes In Coastal California

Routes recording Northern Rough-winged Swallow in Coastal California.
OilfieldsCALIFORNIA772005
OrlandCALIFORNIA401992
CollegevilleCALIFORNIA322002
El ToroCALIFORNIA231999
BakersfieldCALIFORNIA172023
Orange CoveCALIFORNIA152012
Elizabeth LkCALIFORNIA142016
SisquocCALIFORNIA132014
AthloneCALIFORNIA112007
Jofegan 2CALIFORNIA112024
CrestonCALIFORNIA92023
Carrizo PlnCALIFORNIA92021
Cp. PendletonCALIFORNIA82004
PowayCALIFORNIA71980
AdelaidaCALIFORNIA71999
MoragaCALIFORNIA62023
CoyoteCALIFORNIA62024
Anza 2CALIFORNIA62005
Staten Is.CALIFORNIA62024
Foster ParkCALIFORNIA51994
Morro BayCALIFORNIA51991
VentucopaCALIFORNIA52002
GreenfieldCALIFORNIA52024
Glen EllenCALIFORNIA52002
AlamarCALIFORNIA52009

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