Least Bittern
Least Bittern has surged: up 97% on the route-weighted index since 1968.
About the Least Bittern
The Least Bittern (Botaurus exilis) is a North American member of the Herons, Egrets & Bitterns (Ardeidae). In this analysis it is grouped with the wetland birds.
- Size
- 12–51 in long (30–130 cm) — a long-legged wader (typical for the family)
- Habitat
- Marshes, ponds, lakeshores and other freshwater wetlands.
- Diet
- Aquatic invertebrates, small fish, frogs and plant matter.
- Range
- Recorded on 200 Breeding Bird Survey routes across 33 states, most concentrated in the Peninsular Florida.
- Family
- Ardeidae · Wetland birds
Notable Least Bittern Trends
No notable trend signals for Least Bittern. See the full index history below.
Least Bittern Population Forecast
If the recent trend holds, Least Bittern is projected to stay roughly flat through 2029, near 0.02 (95% range 0.01–0.03). A 5-year backtest shows a typical error of ±28.5%, with 100% of held-out values landing inside the 95% band.
| Year | Projected index | 95% low | 95% high |
|---|---|---|---|
| 2025 | 0.02 | 0.01 | 0.03 |
| 2026 | 0.02 | 0.01 | 0.03 |
| 2027 | 0.02 | 0.01 | 0.03 |
| 2028 | 0.02 | 0.01 | 0.03 |
| 2029 | 0.02 | 0.01 | 0.03 |
Where the Least Bittern Is Detected
BBS routes recording Least Bittern, sized by most recent count.
Least Bittern Population Trend by State
| Alabama | -72% | 1971 | 14 |
| Arizona | -56% | 2002 | 3 |
| Arkansas | insufficient data | n/a | 1 |
| California | insufficient data | n/a | 4 |
| Connecticut | insufficient data | n/a | 2 |
| Delaware | insufficient data | n/a | 2 |
| Florida | -55% | 1968 | 36 |
| Georgia | insufficient data | n/a | 3 |
| Illinois | insufficient data | n/a | 3 |
| Indiana | insufficient data | n/a | 1 |
| Iowa | insufficient data | n/a | 1 |
| Kansas | insufficient data | n/a | 3 |
| Louisiana | +302% | 1970 | 18 |
| Maryland | +182% | 1969 | 4 |
| Michigan | -53% | 1978 | 9 |
| Minnesota | -35% | 1976 | 14 |
| Mississippi | insufficient data | n/a | 4 |
| Missouri | insufficient data | n/a | 2 |
| Nebraska | insufficient data | n/a | 2 |
| Nevada | insufficient data | n/a | 1 |
| New Hampshire | insufficient data | n/a | 2 |
| New Jersey | insufficient data | n/a | 2 |
| New York | insufficient data | n/a | 7 |
| North Carolina | -77% | 1974 | 7 |
| North Dakota | insufficient data | n/a | 9 |
| Ohio | insufficient data | n/a | 1 |
| Oregon | insufficient data | n/a | 1 |
| South Carolina | insufficient data | n/a | 1 |
| South Dakota | insufficient data | n/a | 3 |
| Texas | -51% | 1971 | 17 |
| Vermont | insufficient data | n/a | 4 |
| Virginia | insufficient data | n/a | 1 |
| Wisconsin | +17% | 1973 | 18 |
Least Bittern Population Trend by Region
Bird Conservation Regions are the ecological unit for trends.
| Prairie Potholes | +135% | 2004 | 18 |
| Prairie Hardwood Transition | -33% | 1972 | 25 |
| Southeastern Coastal Plain | -72% | 1969 | 27 |
| New England / Mid-Atlantic Coast | +165% | 1969 | 11 |
| Peninsular Florida | -67% | 1968 | 32 |
| Sonoran and Mojave Deserts | -41% | 2001 | 6 |
| Gulf Coastal Prairie | +276% | 1970 | 27 |
Least Bittern Conservation Status
Our route-weighted index shows it up about 97% 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.