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

Pied-billed Grebe Population Trend in Wisconsin

All statesWetland birds

Pied-billed Grebe in Wisconsin has collapsed: down 76% on the route-weighted index since 1968.

-76%Since 1968TrendPercent 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 →
45Routes 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 →
57YearsYears 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 WisconsinNotable 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 collapsed in Wisconsin: down 76% on the route-weighted index since 1968.

Pied-billed Grebe Population Forecast in Wisconsin

If the recent trend holds, Pied-billed Grebe in Wisconsin is projected to stay roughly flat through 2029, near 0.02 (95% range 0.00–0.13). A 5-year backtest shows a typical error of ±48.3%, with 100% of held-out values landing inside the 95% band.

n/aChange 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 →
0.02Projected 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 →
0.00–0.1395% 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 →
±48.3%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 Wisconsin is projected to stay roughly flat through 2029, near 0.02 (95% range 0.00–0.13). A 5-year backtest shows a typical error of ±48.3%, with 100% of held-out values landing inside the 95% band.19662029
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 →
20250.030.000.14
20260.030.000.14
20270.020.000.14
20280.020.000.13
20290.020.000.13

Pied-billed Grebe Survey Routes in Wisconsin

Routes recording Pied-billed Grebe in Wisconsin.
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 →
Fall River720191969
Hudson320161966
Minong219981977
Exeland220031985
Rib Lake220151974
Clintonville220241969
Pardeeville219941991
Princeton220051982
Eden219731973
Grand View120221976
Montreal120222018
Dresser120161967
Union Twp120191967
Loraine120161968
Cumberland120131969
Weyerhauser120141969
Couderay119941974
Gilman120241971
Omro 2120182012
Irma119771977
Eagle River119811981
Hollister119981996
Washington I119701969
Esdaile119801966
Cochrane120162016

Pied-billed Grebe Population Trend in Other States

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

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