BirdAnalyst
Species · California · BBS 2025 Release · 1966–2024

Mallard Population Trend in California

All statesWaterfowl

Mallard in California has surged: up 135% on the route-weighted index since 1970.

+135%Since 1970TrendPercent 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 →
184Routes In StateSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
56YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Mallard Trends in CaliforniaNotable 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 →

Mallard has surged in California: up 135% on the route-weighted index since 1970.

Mallard Population Forecast in California

If the recent trend holds, Mallard in California is projected to rise about 115% by 2029 — from 4.2 in 2024 to a central estimate of 9.0 (95% range 0.79–17). A 5-year backtest shows a typical error of ±336.8%, with 40% of held-out values landing inside the 95% band.

+115%Change by 2029TrendPercent 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 →
9.0Projected 2029 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.79–1795% 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 →
±336.8%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, Mallard in California is projected to rise about 115% by 2029 — from 4.2 in 2024 to a central estimate of 9.0 (95% range 0.79–17). A 5-year backtest shows a typical error of ±336.8%, with 40% of held-out values landing inside the 95% band.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 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 →
20258.70.5017
20268.80.5717
20278.90.6417
20288.90.7117
20299.00.7917

Mallard Survey Routes in California

Routes recording Mallard in 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 →
Dorris15920191972
Likely15720241972
Coalinga12520121975
Copperopolis9320241979
Glenn2920231971
Harbor Lake2719911973
Athlone2520071972
Madeline2520241997
Macdoel2220191973
Iron Gate2220191988
Moraga1920231974
Crowley Lake1820221972
Lockwood Val1720122012
Bakersfield1320181968
Elsinore Mtn1320221974
Fish Rock1220141983
Gravesboro1219951968
Poway1219801974
Atwater1220121971
Ora Loma1220241973
Nubieber1120181970
Bodega Bay1120191976
Buena Vista1120191991
Brawley1020122006
Collegeville 21020232009

Mallard Population Trend in Other States

alabamaalaskaarizonaarkansascoloradoconnecticutdelawarefloridageorgiaidahoillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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