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Species · Wisconsin · BBS 2026 Release · 1966–2025

Vesper Sparrow Population Trend in Wisconsin

All statesGrassland birds

Vesper Sparrow in Wisconsin has collapsed: down 92% on the route-weighted index since 1968.

-92%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 →
90Routes 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 Vesper Sparrow 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 →

Vesper Sparrow has collapsed in Wisconsin: down 92% on the route-weighted index since 1968.

Vesper Sparrow Population Forecast in Wisconsin

If the recent trend holds, Vesper Sparrow in Wisconsin is projected to fall about 100% by 2030 — from 1.2 in 2025 to a central estimate of 0.00 (95% range 0.00–1.8). A 5-year backtest shows a typical error of ±47.3%, with 100% of held-out values landing inside the 95% band.

-100%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 →
0.00Projected 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 →
0.00–1.895% 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 →
±47.3%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, Vesper Sparrow in Wisconsin is projected to fall about 100% by 2030 — from 1.2 in 2025 to a central estimate of 0.00 (95% range 0.00–1.8). A 5-year backtest shows a typical error of ±47.3%, 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 →
20260.120.001.9
20270.000.001.8
20280.000.001.8
20290.000.001.8
20300.000.001.8

Vesper Sparrow Survey Routes in Wisconsin

Routes recording Vesper Sparrow 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 →
Bashaw1120251998
Briggsville1020251999
N Freedom920251966
Fall River720251966
Meridean620251998
Gresham620251998
Union Twp520251966
Wis Rapids520221967
Mount Horeb519901967
Weyerhauser420251966
Oconto Falls420181968
N Andover420211967
Chaffey319951975
Trempealeau320251966
Casco320251971
Pardeeville320251969
Raymond320251966
Buena Vista320251998
Beloit320251998
Minong220251967
Hudson220251966
Dresser220231966
Couderay220191969
Merrill220021966
Wausaukee220251980

Vesper Sparrow Population Trend in Other States

arizonacaliforniacoloradoconnecticutdelawareidahoillinoisindianaiowakansaskentuckymainemarylandmassachusettsmichiganminnesotamissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniasouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawyoming

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