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

Black Tern In Coastal California

All regionsCoastal CaliforniaWetland birds

Black Tern in Coastal California has fallen sharply: down 75% on the route-weighted index since 1973.

-75%Since 1973
5Routes In Region
38Years

Notable Signals

long arc declinecomputed index

Black Tern has fallen sharply in Coastal California: down 75% on the route-weighted index since 1973.

Forecast

If the recent trend holds, Black Tern in Coastal California is projected to stay roughly flat through 2026, near 0.24 (95% range 0.00–0.64). A 5-year backtest shows a typical error of ±760.9%, with 100% of held-out values landing inside the 95% band.

n/aChange by 2026
0.24Projected 2026 index
0.00–0.6495% range
±760.9%Backtest error
19712026
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
20220.230.000.64
20230.240.000.64
20240.240.000.64
20250.240.000.64
20260.240.000.64

Routes In Coastal California

Routes recording Black Tern in Coastal California.
Ora LomaCALIFORNIA431973
OrlandCALIFORNIA21996
GlennCALIFORNIA22021
TranquillityCALIFORNIA21995
HughsonCALIFORNIA11991

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