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Species · Alabama · BBS 2026 Release · 1966–2025

Caspian Tern Population Trend in Alabama

All statesWetland birds

Caspian Tern in Alabama has edged down: down 25% on the route-weighted index since 1970.

-25%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 →
36YearsYears 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 fall about 51% by 2030 — from 0.08 in 2025 to a central estimate of 0.04 (95% range 0.00–0.16). A 5-year backtest shows a typical error of ±48%, with 100% of held-out values landing inside the 95% band.

-51%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 →
0.04Projected 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 →
0.00–0.1695% 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 →
±48%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 fall about 51% by 2030 — from 0.08 in 2025 to a central estimate of 0.04 (95% range 0.00–0.16). A 5-year backtest shows a typical error of ±48%, with 100% of held-out values landing inside the 95% band.19662030
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 →
20260.040.000.16
20270.040.000.16
20280.040.000.16
20290.040.000.16
20300.040.000.16

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 →
St. Elmo420252007
Dauphin Is 2320191991
Alabama Pt220001968
Dauphin Is119901966

Caspian Tern Population Trend in Other States

alaskacaliforniadelawarefloridaidahoillinoisindianalouisianamarylandmichiganminnesotamontananevadanorth-carolinanorth-dakotaoregonsouth-carolinasouth-dakotatexasutahvermontvirginiawashingtonwisconsinwyoming

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