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

Tree Swallow In Coastal California

All regionsCoastal CaliforniaAerial insectivores

Tree Swallow in Coastal California has surged: up 158% on the route-weighted index since 1970.

+158%Since 1970
83Routes In Region
56Years

Notable Signals

long arc increasecomputed index

Tree Swallow has surged in Coastal California: up 158% on the route-weighted index since 1970.

Forecast

If the recent trend holds, Tree Swallow in Coastal California is projected to stay roughly flat through 2029, near 4.6 (95% range 1.2–8.0). A 5-year backtest shows a typical error of ±72.6%, with 100% of held-out values landing inside the 95% band.

-7%Change by 2029
4.6Projected 2029 index
1.2–8.095% range
±72.6%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
20254.41.07.8
20264.41.17.8
20274.51.17.9
20284.51.27.9
20294.61.28.0

Routes In Coastal California

Routes recording Tree Swallow in Coastal California.
OrovilleCALIFORNIA892024
GlennCALIFORNIA702023
AuburnCALIFORNIA411980
MoragaCALIFORNIA362024
El ToroCALIFORNIA231984
CoyoteCALIFORNIA202024
OnoCALIFORNIA182012
OrlandCALIFORNIA142022
CordovaCALIFORNIA131980
Yokohl ValCALIFORNIA111997
CopperopolisCALIFORNIA112024
Tres Pinos 2CALIFORNIA102010
Glen Ellen 2CALIFORNIA102023
CoalingaCALIFORNIA92022
ZamoraCALIFORNIA92024
WestleyCALIFORNIA82024
GravesboroCALIFORNIA71995
Morro BayCALIFORNIA72006
Point ReyesCALIFORNIA72023
SangerCALIFORNIA72024
CrestonCALIFORNIA72024
Gold HillCALIFORNIA72024
StonyfordCALIFORNIA72018
CalpellaCALIFORNIA61986
PenningtonCALIFORNIA62024

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