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

Least Tern In Southeastern Coastal Plain

All regionsSoutheastern Coastal PlainWetland birds

Least Tern in Southeastern Coastal Plain has collapsed: down 97% on the route-weighted index since 1968.

-97%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 →
36Routes 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 →
58YearsYears 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 →

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 Southeastern Coastal Plain: down 97% on the route-weighted index since 1968.

Least Tern In Southeastern Coastal Plain Population Forecast

If the recent trend holds, Least Tern in Southeastern Coastal Plain is projected to stay roughly flat through 2029, near 0.26 (95% range 0.00–1.4). A 5-year backtest shows a typical error of ±1685.7%, with 100% of held-out values landing inside the 95% band.

n/aChange 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 →
0.26Projected 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 →
0.00–1.495% 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 →
±1685.7%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, Least Tern in Southeastern Coastal Plain is projected to stay roughly flat through 2029, near 0.26 (95% range 0.00–1.4). A 5-year backtest shows a typical error of ±1685.7%, with 100% of held-out values landing inside the 95% band.19662029
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 →
20250.340.001.5
20260.320.001.5
20270.300.001.5
20280.280.001.5
20290.260.001.4

Routes In Southeastern Coastal Plain

Routes recording Least 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 →
Santa RosaFLORIDA972003
Ft Waltn BchFLORIDA262011
Milltail CrNORTH-CAROLINA142005
Dauphin IsALABAMA91990
MerrimonNORTH-CAROLINA72023
MashoesNORTH-CAROLINA71974
BackbayVIRGINIA51969
St. ElmoALABAMA42013
Everett CityGEORGIA41998
Alligator PtFLORIDA31988
DarienGEORGIA31992
ArapahoeNORTH-CAROLINA31977
Alabama PtALABAMA22003
Dauphin Is 2ALABAMA22018
Ft GadsdenFLORIDA22014
Doctor InletFLORIDA22000
WadleyGEORGIA21985
GrandyNORTH-CAROLINA21971
Johns IsleSOUTH-CAROLINA21974
HardeevilleSOUTH-CAROLINA22024
Alabama Pt 2ALABAMA12019
Chacaloochee BayALABAMA12016
Broad BranchFLORIDA11997
MiccosukeeFLORIDA12001
Port St JoeFLORIDA12011

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