Least Tern
Least Tern has collapsed: down 90% on the route-weighted index since 1968.
About the Least Tern
The Least Tern (Sternula antillarum) 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 190 Breeding Bird Survey routes across 25 states, most concentrated in the Peninsular Florida.
- Family
- Laridae · Wetland birds
Notable Least Tern Trends
Least Tern has collapsed in surveyed states: down 90% on the route-weighted index since 1968.
Least Tern Population Forecast
If the recent trend holds, Least Tern is projected to stay roughly flat through 2029, near 0.01 (95% range 0.00–0.11). A 5-year backtest shows a typical error of ±79.9%, with 100% of held-out values landing inside the 95% band.
| Year | Projected index | 95% low | 95% high |
|---|---|---|---|
| 2025 | 0.02 | 0.00 | 0.12 |
| 2026 | 0.02 | 0.00 | 0.12 |
| 2027 | 0.01 | 0.00 | 0.12 |
| 2028 | 0.01 | 0.00 | 0.11 |
| 2029 | 0.01 | 0.00 | 0.11 |
Where the Least Tern Is Detected
BBS routes recording Least Tern, sized by most recent count.
Least Tern Population Trend by State
| Alabama | -92% | 1968 | 6 |
| Arkansas | -27% | 1989 | 7 |
| California | +26% | 1974 | 5 |
| Colorado | insufficient data | n/a | 2 |
| Delaware | -88% | 1968 | 7 |
| Florida | -98% | 1968 | 50 |
| Georgia | insufficient data | n/a | 5 |
| Illinois | insufficient data | n/a | 3 |
| Kansas | -41% | 1969 | 5 |
| Kentucky | +126% | 1978 | 3 |
| Louisiana | +46% | 1971 | 15 |
| Maine | insufficient data | n/a | 1 |
| Maryland | -34% | 1980 | 9 |
| Massachusetts | -60% | 1971 | 7 |
| Mississippi | +45% | 1999 | 3 |
| Missouri | insufficient data | n/a | 3 |
| Nebraska | +103% | 2001 | 4 |
| New Jersey | -89% | 1980 | 6 |
| New York | -24% | 1974 | 3 |
| North Carolina | -39% | 1969 | 8 |
| Oklahoma | +85% | 1992 | 8 |
| South Carolina | -22% | 1999 | 3 |
| Tennessee | -28% | 1968 | 3 |
| Texas | +178% | 1971 | 22 |
| Virginia | insufficient data | n/a | 2 |
Least Tern Population Trend by Region
Bird Conservation Regions are the ecological unit for trends.
| Central Mixed Grass Prairie | -29% | 1969 | 12 |
| Eastern Tallgrass Prairie | +8% | 1997 | 7 |
| Mississippi Alluvial Valley | -67% | 1968 | 20 |
| Southeastern Coastal Plain | -97% | 1968 | 36 |
| New England / Mid-Atlantic Coast | -60% | 1968 | 32 |
| Peninsular Florida | -98% | 1968 | 39 |
| Gulf Coastal Prairie | +14% | 1971 | 24 |
Least Tern Conservation Status
Our route-weighted index shows it down about 90% 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.