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

Field Sparrow Population Trend in Wisconsin

All statesForest birds

Field Sparrow in Wisconsin has fallen sharply: down 72% on the route-weighted index since 1968.

-72%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 →
91Routes 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 Field 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 →

Field Sparrow has fallen sharply in Wisconsin: down 72% on the route-weighted index since 1968.

Field Sparrow Population Forecast in Wisconsin

If the recent trend holds, Field Sparrow in Wisconsin is projected to fall about 54% by 2030 — from 2.3 in 2025 to a central estimate of 1.1 (95% range 0.00–2.7). A 5-year backtest shows a typical error of ±43.7%, with 100% of held-out values landing inside the 95% band.

-54%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 →
1.1Projected 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 →
0.00–2.795% 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 →
±43.7%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, Field Sparrow in Wisconsin is projected to fall about 54% by 2030 — from 2.3 in 2025 to a central estimate of 1.1 (95% range 0.00–2.7). A 5-year backtest shows a typical error of ±43.7%, 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 →
20261.40.003.0
20271.30.003.0
20281.20.002.9
20291.10.002.8
20301.10.002.7

Field Sparrow Survey Routes in Wisconsin

Routes recording Field 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 →
Hatfield1319981970
N Freedom1320251966
Wiota1220251966
Union Twp1020251966
Rolling Grnd1020251966
New Lisbon1020251967
Briggsville1020251999
Fall River920251966
Kendall820251967
Eden820251966
River Falls820251998
Meridean720251998
Esdaile620251966
Gilmanton620251966
Bashaw620251998
Highland620251998
Trempealeau520251966
N Andover420251967
Paris420251966
Annaton420251998
Mukwonago 2420252005
Hudson320251966
Mather320231966
Princeton320241966
Mount Horeb319901967

Field Sparrow Population Trend in Other States

alabamaarkansascoloradoconnecticutdelawarefloridageorgiaillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanew-hampshirenew-jerseynew-yorknorth-carolinanorth-dakotaohiooklahomapennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasvermontvirginiawest-virginiawyoming

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