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

Forster's Tern In Southeastern Coastal Plain

All regionsSoutheastern Coastal PlainWetland birds

Forster's Tern in Southeastern Coastal Plain has fallen sharply: down 74% on the route-weighted index since 1969.

-74%Since 1969TrendPercent 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 →
22Routes 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 →
54YearsYears 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 →

Forster's Tern has fallen sharply in Southeastern Coastal Plain: down 74% on the route-weighted index since 1969.

Forster's Tern In Southeastern Coastal Plain Population Forecast

If the recent trend holds, Forster's Tern in Southeastern Coastal Plain is projected to stay roughly flat through 2028, near 0.07 (95% range 0.00–0.20). A 5-year backtest shows a typical error of ±258%, with 100% of held-out values landing inside the 95% band.

n/aChange by 2028TrendPercent 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 →
0.07Projected 2028 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–0.2095% 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 →
±258%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, Forster's Tern in Southeastern Coastal Plain is projected to stay roughly flat through 2028, near 0.07 (95% range 0.00–0.20). A 5-year backtest shows a typical error of ±258%, with 100% of held-out values landing inside the 95% band.19662028
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 →
20240.080.000.20
20250.080.000.20
20260.080.000.20
20270.070.000.20
20280.070.000.20

Routes In Southeastern Coastal Plain

Routes recording Forster's 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 RosaFLORIDA171991
Cross CityFLORIDA152015
Alabama PtALABAMA81997
St Vincent IFLORIDA82010
Alligator PtFLORIDA71993
Ft GadsdenFLORIDA52013
DarienGEORGIA31973
MerrimonNORTH-CAROLINA32023
Myrtle GroveNORTH-CAROLINA32017
Milltail CrNORTH-CAROLINA32022
MattamuskeetNORTH-CAROLINA32019
Port St JoeFLORIDA22007
SupplyNORTH-CAROLINA22000
Dauphin IsALABAMA11988
Dauphin Is 2ALABAMA12005
Chacaloochee BayALABAMA12016
Ft Waltn BchFLORIDA12009
SteinhatcheeFLORIDA11992
KellerGEORGIA11994
NewportNORTH-CAROLINA12023
Kiawah IslandSOUTH-CAROLINA12009
PungoVIRGINIA11994

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