Royal Tern
Royal Tern has fallen sharply: down 70% on the route-weighted index since 1968.
About the Royal Tern
The Royal Tern (Thalasseus maximus) is a North American member of the Gulls, Terns & Skimmers (Laridae). In this analysis it is grouped with the wetland birds.
- Size
- 8.5–31.5 in long (22–80 cm) — a long-winged waterbird (typical for the family)
- Habitat
- Marshes, ponds, lakeshores and other freshwater wetlands.
- Diet
- Aquatic invertebrates, small fish, frogs and plant matter.
- Range
- Recorded on 90 Breeding Bird Survey routes across 12 states, most concentrated in the Southeastern Coastal Plain.
- Family
- Laridae · Wetland birds
Notable Royal Tern Trends
Royal Tern has fallen sharply in surveyed states: down 70% on the route-weighted index since 1968.
Royal Tern Population Forecast
If the recent trend holds, Royal Tern is projected to stay roughly flat through 2029, near 0.04 (95% range 0.00–0.08). A 5-year backtest shows a typical error of ±51.8%, with 100% of held-out values landing inside the 95% band.
| Year | Projected index | 95% low | 95% high |
|---|---|---|---|
| 2025 | 0.04 | 0.00 | 0.09 |
| 2026 | 0.04 | 0.00 | 0.09 |
| 2027 | 0.04 | 0.00 | 0.09 |
| 2028 | 0.04 | 0.00 | 0.08 |
| 2029 | 0.04 | 0.00 | 0.08 |
Where the Royal Tern Is Detected
BBS routes recording Royal Tern, sized by most recent count.
Royal Tern Population Trend by State
| Alabama | +262% | 1971 | 7 |
| California | insufficient data | n/a | 3 |
| Delaware | insufficient data | n/a | 1 |
| Florida | -80% | 1968 | 28 |
| Georgia | insufficient data | n/a | 2 |
| Louisiana | -65% | 1982 | 6 |
| Maryland | insufficient data | n/a | 8 |
| New Jersey | insufficient data | n/a | 1 |
| North Carolina | -81% | 1968 | 11 |
| South Carolina | insufficient data | n/a | 2 |
| Texas | +249% | 1976 | 13 |
| Virginia | -76% | 1978 | 8 |
Royal Tern Population Trend by Region
Bird Conservation Regions are the ecological unit for trends.
| Southeastern Coastal Plain | -66% | 1968 | 33 |
| New England / Mid-Atlantic Coast | -54% | 1969 | 17 |
| Peninsular Florida | -89% | 1968 | 18 |
| Gulf Coastal Prairie | +141% | 1976 | 17 |
Royal Tern Conservation Status
Our route-weighted index shows it down about 70% since 1968.
Source: USGS North American Breeding Bird Survey, retrieved 2026-05-22. Trend is a route-weighted relative-abundance index, not an absolute population.