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Species · Louisiana · BBS 2025 Release · 1966–2024

Swainson's Warbler Population Trend in Louisiana

All statesForest birds

Swainson's Warbler in Louisiana has surged: up 468% on the route-weighted index since 1974.

+468%Since 1974TrendPercent 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 →
50Routes 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 →
51YearsYears 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 LouisianaNotable 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 Louisiana: up 468% on the route-weighted index since 1974.

Swainson's Warbler Population Forecast in Louisiana

If the recent trend holds, Swainson's Warbler in Louisiana is projected to fall about 39% by 2029 — from 1.0 in 2024 to a central estimate of 0.61 (95% range 0.15–1.1). A 5-year backtest shows a typical error of ±45.7%, with 40% of held-out values landing inside the 95% band.

-39%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 →
0.61Projected 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 →
0.15–1.195% 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 →
±45.7%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 Louisiana is projected to fall about 39% by 2029 — from 1.0 in 2024 to a central estimate of 0.61 (95% range 0.15–1.1). A 5-year backtest shows a typical error of ±45.7%, with 40% of held-out values landing inside the 95% band.19672029
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 →
20250.580.121.1
20260.590.131.1
20270.600.131.1
20280.600.141.1
20290.610.151.1

Swainson's Warbler Survey Routes in Louisiana

Routes recording Swainson's Warbler in Louisiana.
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 →
Lake Cove820172008
Trout620241994
Hargis620102006
Goodwill520242021
Grayson520212005
Longstreet420211987
Flat Creek420242000
Womack420242014
Burr Ferry420242015
Atchafalaya320241989
Clay320242021
Enterprise320242011
Mount Union320231998
Tensas Nwr220241987
Plettenberg220221973
Linville220232010
De Ridder220191998
Greensburg220221991
Evelyn220242009
Norwood220232019
Haughton120242010
Freetown119841984
Morgan City119771977
Roseland120021967
Bickham120181984

Swainson's Warbler Population Trend in Other States

alabamaarkansasfloridageorgiakentuckymarylandmississippinorth-carolinaoklahomasouth-carolinatennesseetexasvirginiawest-virginia

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