BirdAnalyst
Species · South Dakota · BBS 2025 Release · 1966–2024

Western Tanager Population Trend in South Dakota

All statesGeneralists

Western Tanager in South Dakota has surged: up 206% on the route-weighted index since 1969.

+206%Since 1969TrendPercent 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 →
17Routes 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 →
57YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Western Tanager Trends in South DakotaNotable 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 increasecomputed 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 →

Western Tanager has surged in South Dakota: up 206% on the route-weighted index since 1969.

Western Tanager Population Forecast in South Dakota

If the recent trend holds, Western Tanager in South Dakota is projected to stay roughly flat through 2029, near 2.8 (95% range 1.5–4.1). A 5-year backtest shows a typical error of ±42.7%, with 100% of held-out values landing inside the 95% band.

+1%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 →
2.8Projected 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 →
1.5–4.195% 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 →
±42.7%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, Western Tanager in South Dakota is projected to stay roughly flat through 2029, near 2.8 (95% range 1.5–4.1). A 5-year backtest shows a typical error of ±42.7%, 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 →
20252.61.43.9
20262.71.44.0
20272.71.54.0
20282.81.54.0
20292.81.54.1

Western Tanager Survey Routes in South Dakota

Routes recording Western Tanager in South Dakota.
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 →
Hazelrodt2920241992
Lightning Cr2320221992
Roubaix Lk1419911967
Silver City1420121992
Custer1320241967
Wind Cave Np1120241999
Elk Mountain920041992
Rochford720181992
Englewood720211992
Pleasant Val620241992
Hill City420131992
Norbeck420021992
Long Draw220241992
Reva120232015
Rosebud120062006
Black Fox120171992
Harding119771977

Western Tanager Population Trend in Other States

alaskaarizonacaliforniacoloradoidahomontananebraskanevadanew-mexicooregontexasutahwashingtonwyoming

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