BirdAnalyst
Species · Florida · BBS 2025 Release · 1966–2024

Forster's Tern Population Trend in Florida

All statesWetland birds

Forster's Tern in Florida has surged: up 111% on the route-weighted index since 1973.

+111%Since 1973TrendPercent 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 →
17Routes 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 →
32YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Forster's Tern Trends in FloridaNotable 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 Florida: up 111% on the route-weighted index since 1973.

Forster's Tern Population Forecast in Florida

If the recent trend holds, Forster's Tern in Florida is projected to fall about 61% by 2029 — from 0.21 in 2024 to a central estimate of 0.08 (95% range 0.00–0.35). A 5-year backtest shows a typical error of ±75.3%, with 80% of held-out values landing inside the 95% band.

-61%Change 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 →
0.08Projected 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 →
0.00–0.3595% 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 →
±75.3%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 Florida is projected to fall about 61% by 2029 — from 0.21 in 2024 to a central estimate of 0.08 (95% range 0.00–0.35). A 5-year backtest shows a typical error of ±75.3%, with 80% of held-out values landing inside the 95% band.19682029
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 →
20250.090.000.36
20260.090.000.36
20270.090.000.36
20280.080.000.35
20290.080.000.35

Forster's Tern Survey Routes in Florida

Routes recording Forster's Tern in Florida.
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 Rosa1719911988
Cross City1520152014
Scottsmoor1220241968
St Vincent I820102010
Mabel819981998
Alligator Pt719931993
Ft Gadsden520131978
Port St Joe220072007
St Augustine220212005
Ft Waltn Bch120091975
Croom119981998
Steinhatchee119921992
Aripeka120042003
Merritt Isl120031999
Childs119881988
Ridge Harbor120022002
Merritt Island 2120142014

Forster's Tern Population Trend in Other States

alabamacaliforniacoloradodelawaregeorgiaidahoillinoisindianaiowakansaslouisianamarylandmichiganminnesotamontananebraskanevadanew-jerseynew-yorknorth-carolinanorth-dakotaoregonsouth-carolinasouth-dakotatexasutahvirginiawashingtonwisconsinwyoming

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