BirdAnalyst
Species · Alabama · BBS 2025 Release · 1966–2024

Least Tern Population Trend in Alabama

All statesWetland birds

Least Tern in Alabama has collapsed: down 92% on the route-weighted index since 1968.

-92%Since 1968TrendPercent 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 →
6Routes 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 →
53YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Least Tern 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 declinecomputed 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 →

Least Tern has collapsed in Alabama: down 92% on the route-weighted index since 1968.

Least Tern Population Forecast in Alabama

If the recent trend holds, Least Tern in Alabama is projected to stay roughly flat through 2024, near 0.29 (95% range 0.00–1.7). A 5-year backtest shows a typical error of ±1133.9%, with 100% of held-out values landing inside the 95% band.

n/aChange by 2024TrendPercent 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 →
0.29Projected 2024 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–1.795% 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 →
±1133.9%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, Least Tern in Alabama is projected to stay roughly flat through 2024, near 0.29 (95% range 0.00–1.7). A 5-year backtest shows a typical error of ±1133.9%, with 100% of held-out values landing inside the 95% band.19662024
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 →
20200.340.001.7
20210.330.001.7
20220.320.001.7
20230.300.001.7
20240.290.001.7

Least Tern Survey Routes in Alabama

Routes recording Least Tern 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 →
Dauphin Is919901966
St. Elmo420132013
Alabama Pt220031969
Dauphin Is 2220181991
Alabama Pt 2120192004
Chacaloochee Bay120162010

Least Tern Population Trend in Other States

arkansascaliforniacoloradodelawarefloridageorgiaillinoiskansaskentuckylouisianamainemarylandmassachusettsmississippimissourinebraskanew-jerseynew-yorknorth-carolinaoklahomasouth-carolinatennesseetexasvirginia

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