Caspian Tern
Caspian Tern has surged: up 81% on the route-weighted index since 1968.
About the Caspian Tern
The Caspian Tern (Hydroprogne caspia) 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 244 Breeding Bird Survey routes across 25 states, most concentrated in the Great Basin.
- Family
- Laridae · Wetland birds
Notable Caspian Tern Trends
No notable trend signals for Caspian Tern. See the full index history below.
Caspian Tern Population Forecast
If the recent trend holds, Caspian Tern is projected to stay roughly flat through 2029, near 0.07 (95% range 0.02–0.13). A 5-year backtest shows a typical error of ±263.2%, with 20% of held-out values landing inside the 95% band.
| Year | Projected index | 95% low | 95% high |
|---|---|---|---|
| 2025 | 0.07 | 0.02 | 0.12 |
| 2026 | 0.07 | 0.02 | 0.12 |
| 2027 | 0.07 | 0.02 | 0.13 |
| 2028 | 0.07 | 0.02 | 0.13 |
| 2029 | 0.07 | 0.02 | 0.13 |
Where the Caspian Tern Is Detected
BBS routes recording Caspian Tern, sized by most recent count.
Caspian Tern Population Trend by State
| Alabama | -30% | 1970 | 4 |
| Alaska | insufficient data | n/a | 1 |
| California | -33% | 1970 | 54 |
| Delaware | insufficient data | n/a | 3 |
| Florida | -12% | 1976 | 22 |
| Idaho | -81% | 1986 | 9 |
| Illinois | insufficient data | n/a | 1 |
| Indiana | insufficient data | n/a | 1 |
| Louisiana | -17% | 1971 | 8 |
| Maryland | insufficient data | n/a | 4 |
| Michigan | -33% | 1983 | 14 |
| Minnesota | -9% | 1985 | 14 |
| Montana | insufficient data | n/a | 8 |
| Nevada | insufficient data | n/a | 4 |
| North Carolina | insufficient data | n/a | 1 |
| North Dakota | insufficient data | n/a | 3 |
| Oregon | -11% | 1975 | 24 |
| South Carolina | insufficient data | n/a | 2 |
| Texas | +2% | 1974 | 15 |
| Utah | +57% | 1995 | 11 |
| Vermont | insufficient data | n/a | 1 |
| Virginia | insufficient data | n/a | 1 |
| Washington | -11% | 1979 | 28 |
| Wisconsin | insufficient data | n/a | 2 |
| Wyoming | insufficient data | n/a | 9 |
Caspian Tern Population Trend by Region
Bird Conservation Regions are the ecological unit for trends.
| Northern Pacific Rainforest | +117% | 1975 | 23 |
| Great Basin | -67% | 1974 | 63 |
| Northern Rockies | -27% | 1988 | 18 |
| Boreal Hardwood Transition | -90% | 1969 | 13 |
| Prairie Hardwood Transition | -18% | 1985 | 16 |
| Southeastern Coastal Plain | -31% | 1970 | 12 |
| New England / Mid-Atlantic Coast | +6% | 1970 | 8 |
| Peninsular Florida | -23% | 1976 | 17 |
| Coastal California | -20% | 1970 | 31 |
| Sonoran and Mojave Deserts | -90% | 1977 | 3 |
| Gulf Coastal Prairie | +3% | 1971 | 17 |
Caspian Tern Conservation Status
Our route-weighted index shows it up about 81% 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.