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Species · Washington · BBS 2025 Release · 1966–2024

Pied-billed Grebe Population Trend in Washington

All statesWetland birds

Pied-billed Grebe in Washington has fallen sharply: down 65% on the route-weighted index since 1973.

-65%Since 1973TrendPercent 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 →
43Routes 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 →
51YearsYears 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 WashingtonNotable 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 Washington: down 65% on the route-weighted index since 1973.

Pied-billed Grebe Population Forecast in Washington

If the recent trend holds, Pied-billed Grebe in Washington is projected to rise about 103% by 2029 — from 0.09 in 2024 to a central estimate of 0.18 (95% range 0.00–0.39). A 5-year backtest shows a typical error of ±120.2%, with 100% of held-out values landing inside the 95% band.

+103%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 →
0.18Projected 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 →
0.00–0.3995% 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 →
±120.2%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 Washington is projected to rise about 103% by 2029 — from 0.09 in 2024 to a central estimate of 0.18 (95% range 0.00–0.39). A 5-year backtest shows a typical error of ±120.2%, with 100% of held-out values landing inside the 95% band.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 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 →
20250.180.000.39
20260.180.000.39
20270.180.000.39
20280.180.000.39
20290.180.000.39

Pied-billed Grebe Survey Routes in Washington

Routes recording Pied-billed Grebe in Washington.
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 →
Brewster620181981
Montesand519901990
Ewan420191985
Othello419911981
Issaquah319761976
Carnation320181989
Chewelah220081983
Wapato219941994
Tonasket220161983
Mendota219811981
Scootney Reservoir220212021
Keystone220151996
Omak Creek220242012
Moses Coulee220232011
Mesa220041997
Port Angeles120181971
Warm Beach120071968
Turnbull Nwr120231993
L Pend O Nwr120232011
Moses Lake120221973
Harrington119831983
Reardan120131998
Bunker Hill120192015
Mendota 2119951992
Rimrock119821982

Pied-billed Grebe Population Trend in Other States

alabamaalaskaarizonaarkansascaliforniacoloradoconnecticutdelawarefloridageorgiaidahoillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniasouth-carolinasouth-dakotatennesseetexasutahvermontvirginiawisconsinwyoming

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