BirdAnalyst
Species · Wisconsin · BBS 2026 Release · 1966–2025

Bobolink Population Trend in Wisconsin

All statesGrassland birds

Bobolink in Wisconsin has collapsed: down 82% on the route-weighted index since 1968.

-82%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 →
92Routes 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 →
59YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Bobolink 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 →

Bobolink has collapsed in Wisconsin: down 82% on the route-weighted index since 1968.

Bobolink Population Forecast in Wisconsin

If the recent trend holds, Bobolink in Wisconsin is projected to fall about 86% by 2030 — from 2.5 in 2025 to a central estimate of 0.35 (95% range 0.00–5.1). A 5-year backtest shows a typical error of ±33.6%, with 100% of held-out values landing inside the 95% band.

-86%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 →
0.35Projected 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 →
0.00–5.195% 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 →
±33.6%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, Bobolink in Wisconsin is projected to fall about 86% by 2030 — from 2.5 in 2025 to a central estimate of 0.35 (95% range 0.00–5.1). A 5-year backtest shows a typical error of ±33.6%, with 100% of held-out values landing inside the 95% band.19662030
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 →
20261.50.006.3
20271.20.006.0
20280.930.005.7
20290.640.005.4
20300.350.005.1

Bobolink Survey Routes in Wisconsin

Routes recording Bobolink 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 →
Holway5319891967
Wis Rapids2520231966
Omro2320011966
Amnicon Falls2120251998
Stetsonville1520251990
Buena Vista1520251998
Stratford1320251966
Eden1220251966
Iron River1120251967
Bayfield1020251967
Kiel1020221998
Hudson920251966
Weyerhauser920251966
Stevens Pt920231966
Rolling Grnd620231966
N Freedom620251966
River Falls620251998
Colby620251998
Prairie Du Chien620251998
Clintonville520251967
Manitowoc520211966
Viroqua520241966
Pt Washingtn520241966
Grimms520211998
Montreal419691969

Bobolink Population Trend in Other States

californiacoloradoconnecticutidahoillinoisindianaiowakansaskentuckymainemarylandmassachusettsmichiganminnesotamissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooregonpennsylvaniarhode-islandsouth-dakotautahvermontvirginiawashingtonwest-virginiawyoming

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