BirdAnalyst
Species · BCR 26 · BBS 2026 Release · 1966–2025

Swainson's Warbler In Mississippi Alluvial Valley

All regionsMississippi Alluvial ValleyForest birds

Swainson's Warbler in Mississippi Alluvial Valley has surged: up 113% on the route-weighted index since 1977.

+113%Since 1977TrendPercent 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 →
18Routes In RegionSurvey 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 SignalsNotable 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 Mississippi Alluvial Valley: up 113% on the route-weighted index since 1977.

Swainson's Warbler In Mississippi Alluvial Valley Population Forecast

If the recent trend holds, Swainson's Warbler in Mississippi Alluvial Valley is projected to rise about 107% by 2030 — from 0.11 in 2025 to a central estimate of 0.23 (95% range 0.02–0.44). A 5-year backtest shows a typical error of ±46.2%, with 100% of held-out values landing inside the 95% band.

+107%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 →
0.23Projected 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 →
0.02–0.4495% 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 →
±46.2%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 Mississippi Alluvial Valley is projected to rise about 107% by 2030 — from 0.11 in 2025 to a central estimate of 0.23 (95% range 0.02–0.44). A 5-year backtest shows a typical error of ±46.2%, 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 →
20260.220.010.43
20270.230.010.44
20280.230.010.44
20290.230.020.44
20300.230.020.44

Routes In Mississippi Alluvial Valley

Routes recording Swainson's Warbler in Mississippi Alluvial Valley.
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 →
South BendARKANSAS11977
GillettARKANSAS12024
Crowley'S RidgeARKANSAS12025
BardwellKENTUCKY11999
Bardwell 2KENTUCKY12024
FreetownLOUISIANA11984
Morgan CityLOUISIANA11977
RoselandLOUISIANA12002
BrousvilleLOUISIANA12014
GonzalesLOUISIANA12014
FrogmoreLOUISIANA12025
KraemerLOUISIANA12003
Port AllenLOUISIANA12003
Morgan CityLOUISIANA12013
Tensas NwrLOUISIANA12025
AtchafalayaLOUISIANA12025
Delta N.F.MISSISSIPPI12008
TiptonvilleTENNESSEE12013

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