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

Pied-billed Grebe Population Trend in California

All statesWetland birds

Pied-billed Grebe in California has held roughly steady: up 3% on the route-weighted index since 1971.

+3%Since 1971TrendPercent 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 →
97Routes 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 →
55YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Pied-billed Grebe 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 →

No notable trend signals for Pied-billed Grebe in California. See the full index history below.

Pied-billed Grebe Population Forecast in California

If the recent trend holds, Pied-billed Grebe in California is projected to stay roughly flat through 2029, near 0.22 (95% range 0.00–0.45). A 5-year backtest shows a typical error of ±147.9%, with 100% of held-out values landing inside the 95% band.

+1%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 →
0.22Projected 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 →
0.00–0.4595% 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 →
±147.9%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, Pied-billed Grebe in California is projected to stay roughly flat through 2029, near 0.22 (95% range 0.00–0.45). A 5-year backtest shows a typical error of ±147.9%, with 100% of held-out values landing inside the 95% band.19692029
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 →
20250.220.000.45
20260.220.000.45
20270.220.000.45
20280.220.000.45
20290.220.000.45

Pied-billed Grebe Survey Routes in California

Routes recording Pied-billed Grebe 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 →
Crowder Flat1220182003
Point Reyes1020101997
Staten Is.620241994
Ingalls519941979
Jacumba519951986
Jackson519861972
Dorris520191976
Pennington320151979
Harbor Lake319901974
El Toro319801980
Ventucopa319971989
Coyote320241972
Red Bluff220111981
Hullville219961974
Colma219711970
Hughson220241970
Yokohl Val219931993
Coalinga220011978
Big Bear219861969
Auburn219801975
Ono220091997
Mesa Grande219861986
Adelaida220151989
Carrizo Pln219781978
Glenn220151975

Pied-billed Grebe Population Trend in Other States

alabamaalaskaarizonaarkansascoloradoconnecticutdelawarefloridageorgiaidahoillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniasouth-carolinasouth-dakotatennesseetexasutahvermontvirginiawashingtonwisconsinwyoming

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