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

Royal Tern Population Trend in Louisiana

All statesWetland birds

Royal Tern in Louisiana has fallen sharply: down 65% on the route-weighted index since 1982.

-65%Since 1982TrendPercent 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 →
6Routes 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 →
16YearsYears 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 LouisianaNotable 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 fallen sharply in Louisiana: down 65% on the route-weighted index since 1982.

Royal Tern Survey Routes in Louisiana

Routes recording Royal Tern in Louisiana.
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 →
Berwick719891989
Grand Isle320192010
Gran Chenier319821976
Creole319871978
Junior119911991
Forked Island120242024

Royal Tern Population Trend in Other States

alabamacaliforniadelawarefloridageorgiamarylandnew-jerseynorth-carolinasouth-carolinatexasvirginia

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