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

Gull-billed Tern Population Trend in Texas

All statesWetland birds

Gull-billed Tern in Texas has risen sharply: up 63% on the route-weighted index since 1971.

+63%Since 1971TrendPercent 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 →
20Routes 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 →
53YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Gull-billed Tern Trends in TexasNotable 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 →

Gull-billed Tern has risen sharply in Texas: up 63% on the route-weighted index since 1971.

Gull-billed Tern Population Forecast in Texas

If the recent trend holds, Gull-billed Tern in Texas is projected to stay roughly flat through 2029, near 0.27 (95% range 0.00–0.61). A 5-year backtest shows a typical error of ±364.1%, 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 →
0.27Projected 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 →
0.00–0.6195% 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 →
±364.1%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, Gull-billed Tern in Texas is projected to stay roughly flat through 2029, near 0.27 (95% range 0.00–0.61). A 5-year backtest shows a typical error of ±364.1%, with 100% of held-out values landing inside the 95% band.19672029
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 →
20250.260.000.60
20260.260.000.60
20270.270.000.60
20280.270.000.60
20290.270.000.61

Gull-billed Tern Survey Routes in Texas

Routes recording Gull-billed Tern in Texas.
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 →
L. Atascosa Nwr5120231998
Loyola Beach1620072002
Bayside720101994
Winnie420132006
Lag Atascosa320181970
Indianola320241967
Progreso320071997
Petronila219991971
Loyola Beach 2220112010
Bayside 2220041997
Chinquapin220111995
Oyster Lake220211995
Kingsville119871979
Padre Island Pais120152015
Vanderbilt119701970
Stowell120101971
Danbury120122001
Raymondville120241983
Heidelberg120242013
Bayside 3120182005

Gull-billed Tern Population Trend in Other States

alabamacaliforniadelawarefloridageorgialouisianamarylandmississippinorth-carolinasouth-carolinavirginia

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