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

Field Sparrow Population Trend in Wisconsin

All statesGeneralists

Field Sparrow in Wisconsin has fallen sharply: down 73% on the route-weighted index since 1968.

-73%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 →
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 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 73% 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 57% by 2029 — from 2.5 in 2024 to a central estimate of 1.1 (95% range 0.00–2.7). A 5-year backtest shows a typical error of ±39.6%, with 100% of held-out values landing inside the 95% band.

-57%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 →
1.1Projected 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 →
0.00–2.795% 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 →
±39.6%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, Field Sparrow in Wisconsin is projected to fall about 57% by 2029 — from 2.5 in 2024 to a central estimate of 1.1 (95% range 0.00–2.7). A 5-year backtest shows a typical error of ±39.6%, 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 →
20251.40.003.1
20261.30.003.0
20271.20.002.9
20281.10.002.8
20291.10.002.7

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 →
Union Twp1520241966
Briggsville1520241999
Hatfield1319981970
Esdaile1120241966
Wiota1120241966
River Falls1120241998
Gilmanton920241966
Fall River920241966
Saxeville820241966
N Freedom820241966
Paris820241966
Rolling Grnd720241966
New Lisbon720241967
Eden720241966
Highland720241998
Mukwonago 2720242005
Kendall620231967
Meridean620241998
Cochrane420241966
N Andover420241967
Wausaukee320241980
Cadott320241966
Mather320231966
Manawa320241966
Princeton320241966

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 2026-05-22.