BirdAnalyst
Species · BCR 32 · BBS 2026 Release · 1966–2025

Gadwall In Coastal California

All regionsCoastal CaliforniaWaterfowl

Gadwall in Coastal California has risen sharply: up 58% on the route-weighted index since 1976.

+58%Since 1976TrendPercent change in the route-weighted abundance index between a smoothed baseline window and the most recent one. It tracks direction, not absolute population.Full methodology →
30Routes In RegionSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
45YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable SignalsNotable signalsLong-arc shifts the engine flags automatically — sustained declines or increases large enough to stand out from year-to-year noise.Full methodology →

long arc increasecomputed indexTrend sourceWhether the figure is our own computed route-weighted index or an official USGS modeled estimate. The current build labels every trend as computed.Full methodology →

Gadwall has risen sharply in Coastal California: up 58% on the route-weighted index since 1976.

Gadwall In Coastal California Population Forecast

If the recent trend holds, Gadwall in Coastal California is projected to rise about 226% by 2030 — from 0.05 in 2025 to a central estimate of 0.17 (95% range 0.00–0.61). A 5-year backtest shows a typical error of ±583.7%, with 100% of held-out values landing inside the 95% band.

+226%Change by 2030TrendPercent change in the route-weighted abundance index between a smoothed baseline window and the most recent one. It tracks direction, not absolute population.Full methodology →
0.17Projected 2030 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–0.6195% range95% rangeThe 95% uncertainty band around the projection at the forecast horizon. The true value should land inside it most of the time.Full methodology →
±583.7%Backtest errorBacktest errorTypical error when we hold out the most recent years, forecast them, and compare to what actually happened. Lower means a more trustworthy projection.Full methodology →
If the recent trend holds, Gadwall in Coastal California is projected to rise about 226% by 2030 — from 0.05 in 2025 to a central estimate of 0.17 (95% range 0.00–0.61). A 5-year backtest shows a typical error of ±583.7%, with 100% of held-out values landing inside the 95% band.19732030
Projection of the recent trend (dashed) with 80/95% bands — a projection, not a prediction. Habitat, climate, and land use are not modeled.
YearProjected indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →95% low95% rangeThe 95% uncertainty band around the projection at the forecast horizon. The true value should land inside it most of the time.Full methodology →95% high95% rangeThe 95% uncertainty band around the projection at the forecast horizon. The true value should land inside it most of the time.Full methodology →
20260.180.000.62
20270.180.000.62
20280.180.000.62
20290.180.000.61
20300.170.000.61

Routes In Coastal California

Routes recording Gadwall in Coastal California.
Recent countThe raw number of individuals recorded on this route in its most recent survey year. A single-route tally, not a trend.Full methodology →
JacumbaCALIFORNIA201988
PolomaCALIFORNIA152013
Big BearCALIFORNIA111986
Mesa GrandeCALIFORNIA61998
Cp. PendletonCALIFORNIA51991
LockwoodCALIFORNIA42024
Ora LomaCALIFORNIA42024
Tres PinosCALIFORNIA32002
Buena VistaCALIFORNIA32017
PenningtonCALIFORNIA22009
HughsonCALIFORNIA22024
CoalingaCALIFORNIA22000
Point ReyesCALIFORNIA22007
Lake BerryessaCALIFORNIA22023
GlennCALIFORNIA22025
WestleyCALIFORNIA22018
TranquillityCALIFORNIA22000
CopperopolisCALIFORNIA22013
Staten Is.CALIFORNIA22015
OrlandCALIFORNIA12009
FairfaxCALIFORNIA12010
AdelaidaCALIFORNIA11995
Green ValleyCALIFORNIA11988
ArvinCALIFORNIA12015
AtwaterCALIFORNIA12004

Source: USGS North American Breeding Bird Survey, retrieved 2026-08-14.