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Species · Alabama · BBS 2025 Release · 1966–2024

Swainson's Warbler Population Trend in Alabama

All statesForest birds

Swainson's Warbler in Alabama has surged: up 24× on the route-weighted index since 1970.

24×Since 1970TrendPercent 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 →
77Routes 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 →
56YearsYears 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 AlabamaNotable 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 Alabama: up 24× on the route-weighted index since 1970.

Swainson's Warbler Population Forecast in Alabama

If the recent trend holds, Swainson's Warbler in Alabama is projected to fall about 40% by 2029 — from 1.4 in 2024 to a central estimate of 0.84 (95% range 0.52–1.2). A 5-year backtest shows a typical error of ±31.1%, with 40% of held-out values landing inside the 95% band.

-40%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 →
0.84Projected 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 →
0.52–1.295% 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 →
±31.1%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 Alabama is projected to fall about 40% by 2029 — from 1.4 in 2024 to a central estimate of 0.84 (95% range 0.52–1.2). A 5-year backtest shows a typical error of ±31.1%, with 40% of held-out values landing inside the 95% band.19682029
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 →
20250.780.461.1
20260.790.471.1
20270.810.491.1
20280.830.511.1
20290.840.521.2

Swainson's Warbler Survey Routes in Alabama

Routes recording Swainson's Warbler in Alabama.
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 →
Sprott-Cahaba Riv3420141999
Gainestown Ferry1720151999
Greensboro820241970
Holt820242000
Howard720241982
Greensport520241970
Blocton520241970
Linden420232019
Cottonton420241993
Newton420242018
South420242023
Warrior Std320242000
Brundidge320212008
Wedgeworth320241985
Liberty City 2320242017
Vernon320222004
Chacaloochee Bay320192011
Drummond320222018
Millerville220242010
Sunny Eve220222019
Mt Olive220241986
Liberty220222013
Riderwood220171979
Sprague220242009
Billingsley220221972

Swainson's Warbler Population Trend in Other States

arkansasfloridageorgiakentuckylouisianamarylandmississippinorth-carolinaoklahomasouth-carolinatennesseetexasvirginiawest-virginia

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