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Species · Michigan · BBS 2025 Release · 1966–2024

Swainson's Thrush Population Trend in Michigan

All statesForest birds

Swainson's Thrush in Michigan has edged up: up 18% on the route-weighted index since 1973.

+18%Since 1973TrendPercent 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 →
33Routes 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 →
53YearsYears 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 MichiganNotable 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 Michigan. See the full index history below.

Swainson's Thrush Population Forecast in Michigan

If the recent trend holds, Swainson's Thrush in Michigan is projected to rise about 50% by 2029 — from 0.26 in 2024 to a central estimate of 0.38 (95% range 0.04–0.72). A 5-year backtest shows a typical error of ±42.3%, with 100% of held-out values landing inside the 95% band.

+50%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 →
0.38Projected 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 →
0.04–0.7295% 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 →
±42.3%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, Swainson's Thrush in Michigan is projected to rise about 50% by 2029 — from 0.26 in 2024 to a central estimate of 0.38 (95% range 0.04–0.72). A 5-year backtest shows a typical error of ±42.3%, with 100% of held-out values landing inside the 95% band.19672029
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 →
20250.370.030.71
20260.380.040.72
20270.380.040.72
20280.380.040.72
20290.380.040.72

Swainson's Thrush Survey Routes in Michigan

Routes recording Swainson's Thrush in Michigan.
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 →
Big Island Lake820102008
Cluster Lakes620102006
Brush Creek619831983
Herman320221984
Gibbs City320241979
Shingleton320241967
Betchler Lks320161993
Ontonagon220191967
Imp Lake220181992
Brocky Lake219951981
Sidnaw220241994
Scott'S Marsh220102006
Muskallonge220231977
Tahquamenon220241974
Gooseneck220102009
Hiawatha Nf220241992
Bergland120151982
Marenisco120111981
Bootjack119971992
Ned Lake119991986
Maple Grove120062006
Ishpeming120212021
Pine River120182006
Cunard120191975
Creighton120191978

Swainson's Thrush Population Trend in Other States

alaskaarizonacaliforniacoloradoconnecticutidahoillinoismainemarylandmassachusettsminnesotamontananebraskanevadanew-hampshirenew-mexiconew-yorknorth-carolinaoregonpennsylvaniasouth-dakotautahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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