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

Common Merganser In Coastal California

All regionsCoastal CaliforniaWaterfowl

Common Merganser in Coastal California has declined: down 29% on the route-weighted index since 1978.

-29%Since 1978
22Routes In Region
44Years

Notable Signals

No notable trend signals for Common Merganser in Coastal California. See the full index history below.

Forecast

If the recent trend holds, Common Merganser in Coastal California is projected to stay roughly flat through 2029, near 0.25 (95% range 0.02–0.47). A 5-year backtest shows a typical error of ±353.7%, with 40% of held-out values landing inside the 95% band.

n/aChange by 2029
0.25Projected 2029 index
0.02–0.4795% range
±353.7%Backtest error
19702029
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
20250.240.010.46
20260.240.010.47
20270.240.010.47
20280.240.020.47
20290.250.020.47

Routes In Coastal California

Routes recording Common Merganser in Coastal California.
CopperopolisCALIFORNIA52021
OnoCALIFORNIA22012
AdelaidaCALIFORNIA21999
LockwoodCALIFORNIA22024
TomheadCALIFORNIA22005
Red BluffCALIFORNIA11978
RumseyCALIFORNIA11998
CoalingaCALIFORNIA12000
Orange CoveCALIFORNIA12004
Point ReyesCALIFORNIA12021
CohassetCALIFORNIA12019
OrlandCALIFORNIA11998
FairfaxCALIFORNIA12019
FolsomCALIFORNIA12023
Carmel ValCALIFORNIA12018
SangerCALIFORNIA12017
Gold HillCALIFORNIA12019
CoyoteCALIFORNIA12023
GreenfieldCALIFORNIA12021
TracyCALIFORNIA11993
PescaderoCALIFORNIA12012
Hough SpringsCALIFORNIA12002

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