BirdAnalyst
Species · Maine · BBS 2025 Release · 1966–2024

Pied-billed Grebe Population Trend in Maine

All statesWetland birds

Pied-billed Grebe in Maine has risen sharply: up 62% on the route-weighted index since 1977.

+62%Since 1977TrendPercent 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 →
16Routes 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 →
21YearsYears 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 MaineNotable 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 risen sharply in Maine: up 62% on the route-weighted index since 1977.

Pied-billed Grebe Population Forecast in Maine

If the recent trend holds, Pied-billed Grebe in Maine is projected to fall about 40% by 2029 — from 0.10 in 2024 to a central estimate of 0.06 (95% range 0.01–0.12). A 5-year backtest shows a typical error of ±44.6%, with 100% of held-out values landing inside the 95% band.

-40%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 →
0.06Projected 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 →
0.01–0.1295% 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 →
±44.6%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 Maine is projected to fall about 40% by 2029 — from 0.10 in 2024 to a central estimate of 0.06 (95% range 0.01–0.12). A 5-year backtest shows a typical error of ±44.6%, with 100% of held-out values landing inside the 95% band.19722029
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 →
20250.060.010.12
20260.060.010.12
20270.060.010.12
20280.060.010.12
20290.060.010.12

Pied-billed Grebe Survey Routes in Maine

Routes recording Pied-billed Grebe in Maine.
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 →
Seboomook Lk319931993
Grnd Lk Strm219931993
Carrabassett120181995
Charleston120042004
Winn119961996
Reeds120242024
Hudson119781977
Otisfield Gr119801980
Manchester119921974
East Troy119951972
Harmony120242004
Boundary120041995
Brooks120142014
St David120042004
Rome120221996
Aurora120162016

Pied-billed Grebe Population Trend in Other States

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

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