BirdAnalyst
Species · South Dakota · BBS 2026 Release · 1966–2025

Western Tanager Population Trend in South Dakota

All statesForest birds

Western Tanager in South Dakota has surged: up 274% on the route-weighted index since 1969.

+274%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 →
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 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 274% 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 fall about 19% by 2030 — from 3.6 in 2025 to a central estimate of 2.9 (95% range 1.6–4.2). A 5-year backtest shows a typical error of ±26.8%, with 100% of held-out values landing inside the 95% band.

-19%Change by 2030TrendPercent 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 →
2.9Projected 2030 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
1.6–4.295% 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 →
±26.8%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 fall about 19% by 2030 — from 3.6 in 2025 to a central estimate of 2.9 (95% range 1.6–4.2). A 5-year backtest shows a typical error of ±26.8%, with 100% of held-out values landing inside the 95% band.19672030
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 →
20262.81.54.0
20272.81.54.1
20282.81.54.1
20292.91.64.2
20302.91.64.2

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 →
Lightning Cr4220251992
Hazelrodt3020251992
Custer1820251967
Roubaix Lk1419911967
Silver City1420121992
Elk Mountain920041992
Englewood720211992
Pleasant Val620241992
Hill City420131992
Long Draw420251992
Wind Cave Np420251999
Norbeck420021992
Rochford320251992
Reva120232015
Rosebud120062006
Black Fox120171992
Harding119771977

Western Tanager Population Trend in Other States

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Source: USGS North American Breeding Bird Survey, retrieved 2026-08-14.