BirdAnalyst
Species · BCR 37 · BBS 2026 Release · 1966–2025

Forster's Tern In Gulf Coastal Prairie

All regionsGulf Coastal PrairieWetland birds

Forster's Tern in Gulf Coastal Prairie has surged: up 170% on the route-weighted index since 1970.

+170%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 →
35Routes 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 →
55YearsYears 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 increasecomputed 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 surged in Gulf Coastal Prairie: up 170% on the route-weighted index since 1970.

Forster's Tern In Gulf Coastal Prairie Population Forecast

If the recent trend holds, Forster's Tern in Gulf Coastal Prairie is projected to fall about 24% by 2030 — from 3.6 in 2025 to a central estimate of 2.8 (95% range 0.00–6.6). A 5-year backtest shows a typical error of ±56.2%, with 100% of held-out values landing inside the 95% band.

-24%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 →
2.8Projected 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 →
0.00–6.695% 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 →
±56.2%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, Forster's Tern in Gulf Coastal Prairie is projected to fall about 24% by 2030 — from 3.6 in 2025 to a central estimate of 2.8 (95% range 0.00–6.6). A 5-year backtest shows a typical error of ±56.2%, with 100% of held-out values landing inside the 95% band.19672030
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 →
20262.70.006.5
20272.70.006.6
20282.80.006.6
20292.80.006.6
20302.80.006.6

Routes In Gulf Coastal Prairie

Routes recording Forster's Tern in Gulf Coastal Prairie.
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 →
CreoleLOUISIANA611987
L. Atascosa NwrTEXAS422025
Oyster LakeTEXAS282025
Sabine NwrLOUISIANA152008
Sabine Nwr 2LOUISIANA142017
JuniorLOUISIANA101991
WoodlawnLOUISIANA102019
Forked IslandLOUISIANA102024
Grand IsleLOUISIANA92018
Loyola BeachTEXAS82005
BaysideTEXAS82010
Port AcresTEXAS82012
GlencoeLOUISIANA62014
StowellTEXAS62023
Gran ChenierLOUISIANA51973
Hinkles FerTEXAS52006
Bayside 3TEXAS52025
Bayside 2TEXAS42004
IndianolaTEXAS32024
Padre Island PaisTEXAS32015
HackberryLOUISIANA22016
KaplanLOUISIANA21999
Ltl ChenierLOUISIANA22025
Ltl Chenier 2LOUISIANA22011
Forked Island 2LOUISIANA22010

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