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Species · California · BBS 2025 Release · 1966–2024

Clark's Grebe Population Trend in California

All statesWetland birds

Clark's Grebe in California has declined: down 34% on the route-weighted index since 1988.

-34%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 →
23Routes 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 →
38YearsYears 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 186% by 2029 — from 0.11 in 2024 to a central estimate of 0.31 (95% range 0.00–0.90). A 5-year backtest shows a typical error of ±506.3%, with 100% of held-out values landing inside the 95% band.

+186%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 →
0.31Projected 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 →
0.00–0.9095% 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 →
±506.3%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 186% by 2029 — from 0.11 in 2024 to a central estimate of 0.31 (95% range 0.00–0.90). A 5-year backtest shows a typical error of ±506.3%, with 100% of held-out values landing inside the 95% band.19862029
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 →
20250.300.000.89
20260.300.000.89
20270.310.000.90
20280.310.000.90
20290.310.000.90

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
Coyote420242001
Lake Berryessa420242023
Nubieber319991991
Madeline320192019
San Ysidro319911986
Hughson220241988
Moraga220102004
Bartlett Sps220152003
Ingalls219991986
Eagle Lake120212002
Likely120142014
Crowder Flat120112011
Haiwee Res119931993
Foster Park119931993
Clear Lk Res120171987
Hollister120011999
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 2026-05-22.