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Species · Arizona · BBS 2026 Release · 1966–2025

Pied-billed Grebe Population Trend in Arizona

All statesWetland birds

Pied-billed Grebe in Arizona has surged: up 80% on the route-weighted index since 1992.

+80%Since 1992TrendPercent 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 →
9Routes 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 →
34YearsYears 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 ArizonaNotable 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 increasecomputed 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 surged in Arizona: up 80% on the route-weighted index since 1992.

Pied-billed Grebe Population Forecast in Arizona

If the recent trend holds, Pied-billed Grebe in Arizona is projected to fall about 13% by 2030 — from 0.17 in 2025 to a central estimate of 0.15 (95% range 0.00–0.30). A 5-year backtest shows a typical error of ±45.3%, with 100% of held-out values landing inside the 95% band.

-13%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 →
0.15Projected 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 →
0.00–0.3095% 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 →
±45.3%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 Arizona is projected to fall about 13% by 2030 — from 0.17 in 2025 to a central estimate of 0.15 (95% range 0.00–0.30). A 5-year backtest shows a typical error of ±45.3%, with 100% of held-out values landing inside the 95% band.19852030
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 →
20260.140.000.29
20270.150.000.30
20280.150.000.30
20290.150.000.30
20300.150.000.30

Pied-billed Grebe Survey Routes in Arizona

Routes recording Pied-billed Grebe in Arizona.
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 →
Alpine720251996
Cibola Lake420221993
Willow Beach 2420212018
Araby220231996
Prescott120191985
Redington119941994
Laguna120152010
Carr Mtn120152015
Alamo Res.120232001

Pied-billed Grebe Population Trend in Other States

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

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