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

American Bittern Population Trend in California

All statesWetland birds

American Bittern in California has declined: down 34% on the route-weighted index since 1972.

-34%Since 1972
36Routes In State
53Years

Notable American Bittern Trends in California

No notable trend signals for American Bittern in California. See the full index history below.

American Bittern Population Forecast in California

If the recent trend holds, American Bittern in California is projected to rise about 159% by 2029 — from 0.05 in 2024 to a central estimate of 0.14 (95% range 0.00–0.40). A 5-year backtest shows a typical error of ±495.9%, with 100% of held-out values landing inside the 95% band.

+159%Change by 2029
0.14Projected 2029 index
0.00–0.4095% range
±495.9%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
20250.150.000.41
20260.150.000.41
20270.140.000.41
20280.140.000.41
20290.140.000.40

American Bittern Survey Routes in California

Routes recording American Bittern in California.
Glenn1320231971
Cordova319751975
Honey Lake320241972
Dorris320191975
Macdoel320171983
Nubieber220071990
Pennington220141971
Arvin219851985
Davis Creek219991993
Tranquillity220031972
Ora Loma219831972
Athlone219821982
Whiskeytown220052003
Gazelle120162016
Red Bluff120141972
Creston120022002
Shafter119861986
Collegeville119791968
Hughson119871982
Atwater120071976
Likely120241975
Crowley Lake119721972
Gold Hill119861986
Oilfields119681968
Gravesboro119851972

American Bittern Population Trend in Other States

alaskacoloradoconnecticutdelawarefloridageorgiaidahoillinoisindianaiowakansaslouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-dakotaohiooklahomaoregonpennsylvaniasouth-carolinasouth-dakotatexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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