Heermann's Gull
Heermann's Gull has collapsed: down 97% on the route-weighted index since 1981.
About the Heermann's Gull
The Heermann's Gull (Larus heermanni) 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 11 Breeding Bird Survey routes across 3 states, most concentrated in the Northern Pacific Rainforest.
- Family
- Laridae · Wetland birds
Notable Heermann's Gull Trends
No notable trend signals for Heermann's Gull. See the full index history below.
Heermann's Gull Population Forecast
If the recent trend holds, Heermann's Gull is projected to stay roughly flat through 2024, near 0.00 (95% range 0.00–0.02). A 5-year backtest shows a typical error of ±964.8%, with 100% of held-out values landing inside the 95% band.
| Year | Projected index | 95% low | 95% high |
|---|---|---|---|
| 2020 | 0.00 | 0.00 | 0.02 |
| 2021 | 0.00 | 0.00 | 0.02 |
| 2022 | 0.00 | 0.00 | 0.02 |
| 2023 | 0.00 | 0.00 | 0.02 |
| 2024 | 0.00 | 0.00 | 0.02 |
Where the Heermann's Gull Is Detected
BBS routes recording Heermann's Gull, sized by most recent count.
Heermann's Gull Population Trend by State
| California | -95% | 1981 | 7 |
| Oregon | insufficient data | n/a | 2 |
| Washington | insufficient data | n/a | 2 |
Heermann's Gull Population Trend by Region
Bird Conservation Regions are the ecological unit for trends.
| Northern Pacific Rainforest | -86% | 1981 | 7 |
Heermann's Gull Conservation Status
Our route-weighted index shows it down about 97% since 1981.
Source: USGS North American Breeding Bird Survey, retrieved 2026-05-22. Trend is a route-weighted relative-abundance index, not an absolute population.