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Species · Wisconsin · BBS 2025 Release · 1966–2024

Swainson's Thrush Population Trend in Wisconsin

All statesForest birds

Swainson's Thrush in Wisconsin has fallen sharply: down 53% on the route-weighted index since 1971.

-53%Since 1971TrendPercent 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 →
21Routes 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 →
46YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Swainson's Thrush 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 →

No notable trend signals for Swainson's Thrush in Wisconsin. See the full index history below.

Swainson's Thrush Population Forecast in Wisconsin

If the recent trend holds, Swainson's Thrush in Wisconsin is projected to stay roughly flat through 2028, near 0.04 (95% range 0.00–0.09). A 5-year backtest shows a typical error of ±229.5%, with 100% of held-out values landing inside the 95% band.

n/aChange by 2028TrendPercent 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 →
0.04Projected 2028 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–0.0995% 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 →
±229.5%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, Swainson's Thrush in Wisconsin is projected to stay roughly flat through 2028, near 0.04 (95% range 0.00–0.09). A 5-year backtest shows a typical error of ±229.5%, with 100% of held-out values landing inside the 95% band.19682028
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 →
20240.040.000.09
20250.040.000.09
20260.040.000.09
20270.040.000.09
20280.040.000.09

Swainson's Thrush Survey Routes in Wisconsin

Routes recording Swainson's Thrush 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 Twp319931993
Casco319881987
Chaffey219951972
Grand View220181973
Hatfield219971997
Iron River120052005
Bayfield120231971
Shanagolden120121980
Montreal120111982
Land O Lakes120131978
Dresser119731968
Eagle River119831983
Popple River120191968
Crandon119901990
Cadott119971997
Manawa120022002
Oconto Falls120161979
Mellen120141998
Conover120132012
Flambeau120062006
Rhinelander119981998

Swainson's Thrush Population Trend in Other States

alaskaarizonacaliforniacoloradoconnecticutidahoillinoismainemarylandmassachusettsmichiganminnesotamontananebraskanevadanew-hampshirenew-mexiconew-yorknorth-carolinaoregonpennsylvaniasouth-dakotautahvermontvirginiawashingtonwest-virginiawyoming

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