BirdAnalyst
Species · BCR 27 · BBS 2025 Release · 1966–2024

Caspian Tern In Southeastern Coastal Plain

All regionsSoutheastern Coastal PlainWetland birds

Caspian Tern in Southeastern Coastal Plain has declined: down 31% on the route-weighted index since 1970.

-31%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 →
12Routes In RegionSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
40YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable SignalsNotable 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 Southeastern Coastal Plain. See the full index history below.

Caspian Tern In Southeastern Coastal Plain Population Forecast

If the recent trend holds, Caspian Tern in Southeastern Coastal Plain is projected to stay roughly flat through 2024, near 0.03 (95% range 0.00–0.08). A 5-year backtest shows a typical error of ±19.1%, 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 →
0.03Projected 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 →
0.00–0.0895% 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 →
±19.1%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, Caspian Tern in Southeastern Coastal Plain is projected to stay roughly flat through 2024, near 0.03 (95% range 0.00–0.08). A 5-year backtest shows a typical error of ±19.1%, 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 →
20200.030.000.08
20210.030.000.08
20220.030.000.08
20230.030.000.08
20240.030.000.08

Routes In Southeastern Coastal Plain

Routes recording Caspian Tern in Southeastern Coastal Plain.
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 2ALABAMA32019
Alabama PtALABAMA22000
Ft Waltn BchFLORIDA22002
St Vincent IFLORIDA22019
Johns IsleSOUTH-CAROLINA21968
Dauphin IsALABAMA11990
St. ElmoALABAMA12007
Port St JoeFLORIDA12008
Ft GadsdenFLORIDA11979
Santa RosaFLORIDA11998
MerrimonNORTH-CAROLINA12002
Kiawah IslandSOUTH-CAROLINA11999

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