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Species · Utah · BBS 2025 Release · 1966–2024

Swainson's Thrush Population Trend in Utah

All statesForest birds

Swainson's Thrush in Utah has collapsed: down 92% on the route-weighted index since 1975.

-92%Since 1975TrendPercent 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 →
29Routes 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 →
43YearsYears 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 UtahNotable 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 →

Swainson's Thrush has collapsed in Utah: down 91% on the route-weighted index since 1975.

Swainson's Thrush Population Forecast in Utah

If the recent trend holds, Swainson's Thrush in Utah is projected to fall about 100% by 2029 — from 0.19 in 2024 to a central estimate of 0.00 (95% range 0.00–3.5). A 5-year backtest shows a typical error of ±506.3%, with 100% of held-out values landing inside the 95% band.

-100%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 →
0.00Projected 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 →
0.00–3.595% 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 →
±506.3%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 Utah is projected to fall about 100% by 2029 — from 0.19 in 2024 to a central estimate of 0.00 (95% range 0.00–3.5). A 5-year backtest shows a typical error of ±506.3%, with 100% of held-out values landing inside the 95% band.19702029
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 →
20250.000.003.5
20260.000.003.5
20270.000.003.5
20280.000.003.5
20290.000.003.5

Swainson's Thrush Survey Routes in Utah

Routes recording Swainson's Thrush in Utah.
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 →
Hyrum1719791975
Moon Lake 2920232004
Main Canyon920032003
Soapstone620241992
Moon Lake620021995
Beck319701970
Beaver319731973
Gooseberry320241996
Uintah Nf319941991
Fish Lake Nf319961996
Logan Canyon220191997
Ferron220182009
Hardware Ranch220231994
Ant Flat-Ogden Can220231994
Altonah120151975
Grizzly Rdge120181987
Lost Cr. Res120181995
Oak City119961996
Saleratus Cr119971997
La Sal 2120062006
E. Bear Lake120212021
Red Spur Mtn.120081997
Navajo Lake120012001
Hite119921992
Skyline Driv120032003

Swainson's Thrush Population Trend in Other States

alaskaarizonacaliforniacoloradoconnecticutidahoillinoismainemarylandmassachusettsmichiganminnesotamontananebraskanevadanew-hampshirenew-mexiconew-yorknorth-carolinaoregonpennsylvaniasouth-dakotavermontvirginiawashingtonwest-virginiawisconsinwyoming

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