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

Caspian Tern Population Trend in Alabama

All statesWetland birds

Caspian Tern in Alabama has declined: down 30% on the route-weighted index since 1970.

-30%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 →
4Routes 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 →
35YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Caspian 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 →

No notable trend signals for Caspian Tern in Alabama. See the full index history below.

Caspian Tern Population Forecast in Alabama

If the recent trend holds, Caspian Tern in Alabama is projected to stay roughly flat through 2024, near 0.04 (95% range 0.00–0.16). A 5-year backtest shows a typical error of ±57.2%, 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 →
0.04Projected 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 →
0.00–0.1695% 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 →
±57.2%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, Caspian Tern in Alabama is projected to stay roughly flat through 2024, near 0.04 (95% range 0.00–0.16). A 5-year backtest shows a typical error of ±57.2%, 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 →
20200.040.000.17
20210.040.000.17
20220.040.000.17
20230.040.000.16
20240.040.000.16

Caspian Tern Survey Routes in Alabama

Routes recording Caspian 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 Is 2320191991
Alabama Pt220001968
Dauphin Is119901966
St. Elmo120072007

Caspian Tern Population Trend in Other States

alaskacaliforniadelawarefloridaidahoillinoisindianalouisianamarylandmichiganminnesotamontananevadanorth-carolinanorth-dakotaoregonsouth-carolinatexasutahvermontvirginiawashingtonwisconsinwyoming

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