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

Royal Tern Population Trend in Florida

All statesWetland birds

Royal Tern in Florida has collapsed: down 80% on the route-weighted index since 1968.

-80%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 →
28Routes 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 →
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 Royal 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 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 →

Royal Tern has collapsed in Florida: down 80% on the route-weighted index since 1968.

Royal Tern Population Forecast in Florida

If the recent trend holds, Royal Tern in Florida is projected to fall about 57% by 2029 — from 0.09 in 2024 to a central estimate of 0.04 (95% range 0.00–0.76). A 5-year backtest shows a typical error of ±60.6%, with 100% of held-out values landing inside the 95% band.

-57%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 →
0.04Projected 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 →
0.00–0.7695% 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 →
±60.6%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, Royal Tern in Florida is projected to fall about 57% by 2029 — from 0.09 in 2024 to a central estimate of 0.04 (95% range 0.00–0.76). A 5-year backtest shows a typical error of ±60.6%, 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 →
20250.090.000.81
20260.070.000.79
20270.060.000.78
20280.050.000.77
20290.040.000.76

Royal Tern Survey Routes in Florida

Routes recording Royal 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 →
Alligator Pt1820221991
Vero Beach720181994
Scottsmoor520241972
Boca Raton419881968
Steinhatchee319741974
Merritt Island 2320142014
Santa Rosa320031987
Ft Waltn Bch220081966
Doctors Inlet 2220172017
Merritt Isl220081991
San Antonio219911991
St Vincent I220171997
Sugarloaf Key 2220182018
Cross City220151996
Indiantown 2120212021
Port St Joe120131969
Ft Gadsden119801972
St Augustine120231976
Ridge Harbor120172017
Indiantown120011995
Plantation K120041966
Card Sound120212001
Sugarloaf Key120041999
Sebastian119911991
Shawano120012001

Royal Tern Population Trend in Other States

alabamacaliforniadelawaregeorgialouisianamarylandnew-jerseynorth-carolinasouth-carolinatexasvirginia

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