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Species · California · BBS 2026 Release · 1966–2025

Clark's Grebe Population Trend in California

All statesWetland birds

Clark's Grebe in California has edged down: down 22% on the route-weighted index since 1988.

-22%Since 1988TrendPercent 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 →
24Routes 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 →
39YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Clark's 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 Clark's Grebe in California. See the full index history below.

Clark's Grebe Population Forecast in California

If the recent trend holds, Clark's Grebe in California is projected to rise about 203% by 2030 — from 0.09 in 2025 to a central estimate of 0.28 (95% range 0.00–0.87). A 5-year backtest shows a typical error of ±579.8%, with 100% of held-out values landing inside the 95% band.

+203%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 →
0.28Projected 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 →
0.00–0.8795% 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 →
±579.8%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, Clark's Grebe in California is projected to rise about 203% by 2030 — from 0.09 in 2025 to a central estimate of 0.28 (95% range 0.00–0.87). A 5-year backtest shows a typical error of ±579.8%, with 100% of held-out values landing inside the 95% band.19862030
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 →
20260.280.000.87
20270.280.000.87
20280.280.000.87
20290.280.000.87
20300.280.000.87

Clark's Grebe Survey Routes in California

Routes recording Clark's 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 →
Iron Gate1120191988
Dorris1120191986
Buena Vista620192019
Nubieber319991991
Madeline320192019
San Ysidro319911986
Lake Berryessa320252023
Hughson220251988
Moraga220102004
Bartlett Sps220152003
Ingalls219991986
Glen Ellen 3220252025
Eagle Lake120212002
Likely120142014
Crowder Flat120112011
Haiwee Res119931993
Foster Park119931993
Clear Lk Res120171987
Hollister120011999
Coyote120252001
Copperopolis120211991
Ora Loma120232023
Staten Is.120102008
Folsom119871987

Clark's Grebe Population Trend in Other States

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