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Species · Virginia · BBS 2025 Release · 1966–2024

Swainson's Warbler Population Trend in Virginia

All statesForest birds

Swainson's Warbler in Virginia has surged: up 115% on the route-weighted index since 1975.

+115%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 →
9Routes 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 →
45YearsYears 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 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 Virginia: up 115% on the route-weighted index since 1975.

Swainson's Warbler Population Forecast in Virginia

If the recent trend holds, Swainson's Warbler in Virginia is projected to rise about 21% by 2029 — from 0.12 in 2024 to a central estimate of 0.14 (95% range 0.00–0.28). A 5-year backtest shows a typical error of ±190.5%, with 100% of held-out values landing inside the 95% band.

+21%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 →
0.14Projected 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 →
0.00–0.2895% 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 →
±190.5%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 Virginia is projected to rise about 21% by 2029 — from 0.12 in 2024 to a central estimate of 0.14 (95% range 0.00–0.28). A 5-year backtest shows a typical error of ±190.5%, with 100% of held-out values landing inside the 95% band.19692029
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 →
20250.130.000.28
20260.140.000.28
20270.140.000.28
20280.140.000.28
20290.140.000.28

Swainson's Warbler Survey Routes in Virginia

Routes recording Swainson's Warbler in 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 →
Dismal Swamp420161992
Pine Mtn.320241996
Newsoms220242012
Saltville119971972
Branchville120161969
Isom120241978
Cornland119751975
Iron Mtn.120002000
Iron Mountain 3120212021

Swainson's Warbler Population Trend in Other States

alabamaarkansasfloridageorgiakentuckylouisianamarylandmississippinorth-carolinaoklahomasouth-carolinatennesseetexaswest-virginia

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