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

Bobolink Population Trend in Wisconsin

All statesGrassland birds

Bobolink in Wisconsin has collapsed: down 81% on the route-weighted index since 1968.

-81%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 →
58YearsYears 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 81% 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 77% by 2029 — from 2.6 in 2024 to a central estimate of 0.59 (95% range 0.00–5.4). A 5-year backtest shows a typical error of ±30%, with 100% of held-out values landing inside the 95% band.

-77%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 →
0.59Projected 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 →
0.00–5.495% 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 →
±30%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 77% by 2029 — from 2.6 in 2024 to a central estimate of 0.59 (95% range 0.00–5.4). A 5-year backtest shows a typical error of ±30%, 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 →
20251.70.006.6
20261.50.006.3
20271.20.006.0
20280.880.005.7
20290.590.005.4

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
Iron River1720241967
Amnicon Falls1720241998
Weirgor Springs1720241999
Bayfield1120241967
Buena Vista1120241998
Weyerhauser1020241966
Gilman1020241966
Kiel1020221998
Hudson920241966
Stevens Pt920231966
Colby920241998
Stratford720241966
Rolling Grnd620231966
Eden620241966
Washington I520241967
Manitowoc520211966
Viroqua520241966
Brownsville520211966
Pt Washingtn520241966
Grimms520211998
Prairie Du Chien520241998
Chaffey420231966

Bobolink Population Trend in Other States

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

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