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Species · West Virginia · BBS 2026 Release · 1966–2025

Swainson's Warbler Population Trend in West Virginia

All statesForest birds

Swainson's Warbler in West Virginia has surged: up 310% on the route-weighted index since 1975.

+310%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 →
15Routes 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 →
42YearsYears 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 Warbler Trends in West VirginiaNotable 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 →

Swainson's Warbler has surged in West Virginia: up 310% on the route-weighted index since 1975.

Swainson's Warbler Population Forecast in West Virginia

If the recent trend holds, Swainson's Warbler in West Virginia is projected to fall about 38% by 2030 — from 0.40 in 2025 to a central estimate of 0.25 (95% range 0.06–0.43). A 5-year backtest shows a typical error of ±67.2%, with 0% of held-out values landing inside the 95% band.

-38%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 →
0.25Projected 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 →
0.06–0.4395% 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 →
±67.2%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 Warbler in West Virginia is projected to fall about 38% by 2030 — from 0.40 in 2025 to a central estimate of 0.25 (95% range 0.06–0.43). A 5-year backtest shows a typical error of ±67.2%, with 0% of held-out values landing inside the 95% band.19692030
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 →
20260.230.040.42
20270.230.050.42
20280.240.050.42
20290.240.060.43
20300.250.060.43

Swainson's Warbler Survey Routes in West Virginia

Routes recording Swainson's Warbler in West Virginia.
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 →
Hanover520251980
Ghent420251990
Clear Creek420251988
Welch320251980
Yawkey320241969
Stollings220211986
Hix119701970
Breeden120232012
Bowden120182018
Hubbardstown120182018
Clendenin119931993
Fayetteville119961989
Olcott120242024
Sutton120242024
Strange Crk120251993

Swainson's Warbler Population Trend in Other States

alabamaarkansasfloridageorgiakentuckylouisianamarylandmississippinorth-carolinaoklahomasouth-carolinatennesseetexasvirginia

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