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Species · Montana · BBS 2025 Release · 1966–2024

Pied-billed Grebe Population Trend in Montana

All statesWetland birds

Pied-billed Grebe in Montana has declined: down 27% on the route-weighted index since 1972.

-27%Since 1972TrendPercent 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 →
36Routes 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 →
52YearsYears 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 MontanaNotable 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 Pied-billed Grebe in Montana. See the full index history below.

Pied-billed Grebe Population Forecast in Montana

If the recent trend holds, Pied-billed Grebe in Montana is projected to fall about 60% by 2029 — from 0.14 in 2024 to a central estimate of 0.06 (95% range 0.00–0.24). A 5-year backtest shows a typical error of ±28.3%, with 100% of held-out values landing inside the 95% band.

-60%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 →
0.00–0.2495% 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 →
±28.3%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 Montana is projected to fall about 60% by 2029 — from 0.14 in 2024 to a central estimate of 0.06 (95% range 0.00–0.24). A 5-year backtest shows a typical error of ±28.3%, 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 →
20250.070.000.25
20260.060.000.25
20270.060.000.25
20280.060.000.24
20290.060.000.24

Pied-billed Grebe Survey Routes in Montana

Routes recording Pied-billed Grebe in Montana.
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 →
Kalispell420241971
Albion420141994
Augusta320241979
Cleveland220172017
Malta219871975
Oswego219971978
Roy220171989
Savage219801980
Forsyth220192019
Saco220232015
Westby220242015
St Mary119951987
Hay Lake119941994
Sunburst120042004
Virgelle120232019
Glen120192019
Willow Creek 2120062006
Polson119941990
Arlee119901990
Leroy120192019
Brusett120241982
Jordan120181968
Two Dot120171980
Flatwillow119911991
Ingomar120161976

Pied-billed Grebe Population Trend in Other States

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

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