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Species · Wisconsin · BBS 2025 Release · 1966–2024

Henslow's Sparrow Population Trend in Wisconsin

All statesGrassland birds

Henslow's Sparrow in Wisconsin has collapsed: down 84% on the route-weighted index since 1968.

-84%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 →
65Routes 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 Henslow's 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 →

Henslow's Sparrow has collapsed in Wisconsin: down 84% on the route-weighted index since 1968.

Henslow's Sparrow Population Forecast in Wisconsin

If the recent trend holds, Henslow's Sparrow in Wisconsin is projected to stay roughly flat through 2029, near 0.00 (95% range 0.00–0.21). A 5-year backtest shows a typical error of ±89.4%, 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 →
0.00Projected 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 →
0.00–0.2195% 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 →
±89.4%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, Henslow's Sparrow in Wisconsin is projected to stay roughly flat through 2029, near 0.00 (95% range 0.00–0.21). A 5-year backtest shows a typical error of ±89.4%, 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 →
20250.020.000.23
20260.010.000.23
20270.010.000.22
20280.010.000.22
20290.000.000.21

Henslow's Sparrow Survey Routes in Wisconsin

Routes recording Henslow's 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 →
Trempealeau1819841984
Highland420122000
Gilmanton320191978
Buena Vista320222000
Minong220092009
Rib Lake219911991
Unity219761967
Clintonville219831983
Pardeeville220051976
Fall River220181967
Wiota220021970
Mount Horeb219821967
Hebron219861968
Briggsville220222003
Stetsonville219941991
Prairie Du Chien220132013
Hudson119851966
Dresser120171966
Loraine120121966
Cumberland120101970
Weyerhauser120211979
Couderay119731973
Exeland119831968
Gilman119821970
Holway119761968

Henslow's Sparrow Population Trend in Other States

delawareillinoisindianaiowakansaskentuckymarylandmichiganminnesotamissourinebraskanew-yorknorth-carolinanorth-dakotaohiooklahomapennsylvaniasouth-dakotavermontvirginiawest-virginia

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