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Species · BCR 15 · BBS 2026 Release · 1966–2025

Pied-billed Grebe In Sierra Nevada

All regionsSierra NevadaWetland birds

Pied-billed Grebe in Sierra Nevada has fallen sharply: down 67% on the route-weighted index since 1975.

-67%Since 1975TrendPercent 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 →
12Routes In RegionSurvey 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 SignalsNotable 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 declinecomputed 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 →

Pied-billed Grebe has fallen sharply in Sierra Nevada: down 67% on the route-weighted index since 1975.

Pied-billed Grebe In Sierra Nevada Population Forecast

If the recent trend holds, Pied-billed Grebe in Sierra Nevada is projected to fall about 22% by 2030 — from 0.11 in 2025 to a central estimate of 0.09 (95% range 0.00–0.35). A 5-year backtest shows a typical error of ±63.3%, with 100% of held-out values landing inside the 95% band.

-22%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 →
0.09Projected 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 →
0.00–0.3595% 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 →
±63.3%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, Pied-billed Grebe in Sierra Nevada is projected to fall about 22% by 2030 — from 0.11 in 2025 to a central estimate of 0.09 (95% range 0.00–0.35). A 5-year backtest shows a typical error of ±63.3%, with 100% of held-out values landing inside the 95% band.19732030
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 →
20260.100.000.35
20270.090.000.35
20280.090.000.35
20290.090.000.35
20300.090.000.35

Routes In Sierra Nevada

Routes recording Pied-billed Grebe in Sierra Nevada.
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 →
Butte MeadowCALIFORNIA21974
Hat CreekCALIFORNIA22018
Eagle LakeCALIFORNIA12025
Tuolumne GroveCALIFORNIA12021
SattleyCALIFORNIA12025
GeneseeCALIFORNIA12012
Higgins CornCALIFORNIA12003
Chaos CraterCALIFORNIA11994
GoumazCALIFORNIA12011
PaxtonCALIFORNIA12011
PlacervilleCALIFORNIA11999
Last ChanceCALIFORNIA12019

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