Double-crested Cormorant
Double-crested Cormorant has surged: up 177% on the route-weighted index since 1968.
About the Double-crested Cormorant
The Double-crested Cormorant (Nannopterum auritum) is a North American member of the Cormorants (Phalacrocoracidae). In this analysis it is grouped with the wetland birds.
- Size
- 27.5–35.5 in long (70–90 cm) — a large diving 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 1,213 Breeding Bird Survey routes across 49 states, most concentrated in the Southeastern Coastal Plain.
- Family
- Phalacrocoracidae · Wetland birds
Notable Double-crested Cormorant Trends
Double-crested Cormorant has surged in surveyed states: up 177% on the route-weighted index since 1968.
Double-crested Cormorant Population Forecast
If the recent trend holds, Double-crested Cormorant is projected to rise about 81% by 2029 — from 0.43 in 2024 to a central estimate of 0.78 (95% range 0.48–1.1). A 5-year backtest shows a typical error of ±82.3%, with 0% of held-out values landing inside the 95% band.
| Year | Projected index | 95% low | 95% high |
|---|---|---|---|
| 2025 | 0.74 | 0.45 | 1.0 |
| 2026 | 0.75 | 0.46 | 1.0 |
| 2027 | 0.76 | 0.46 | 1.1 |
| 2028 | 0.77 | 0.47 | 1.1 |
| 2029 | 0.78 | 0.48 | 1.1 |
Where the Double-crested Cormorant Is Detected
BBS routes recording Double-crested Cormorant, sized by most recent count.
Double-crested Cormorant Population Trend by State
| Alabama | 38× | 1983 | 31 |
| Alaska | insufficient data | n/a | 4 |
| Arizona | -7% | 1991 | 15 |
| Arkansas | +6% | 1999 | 6 |
| California | +69% | 1974 | 73 |
| Colorado | 19× | 1989 | 28 |
| Connecticut | -55% | 1981 | 12 |
| Delaware | +80% | 1975 | 13 |
| Florida | -94% | 1968 | 92 |
| Georgia | -28% | 1984 | 30 |
| Idaho | -76% | 1981 | 17 |
| Illinois | +721% | 1984 | 48 |
| Indiana | -67% | 2011 | 10 |
| Iowa | -75% | 1992 | 11 |
| Kansas | +834% | 1977 | 17 |
| Kentucky | insufficient data | n/a | 8 |
| Louisiana | -32% | 1975 | 27 |
| Maine | +42% | 1971 | 34 |
| Maryland | +683% | 1981 | 40 |
| Massachusetts | +100% | 1971 | 23 |
| Michigan | -69% | 1991 | 15 |
| Minnesota | +241% | 1975 | 54 |
| Mississippi | 13× | 2008 | 10 |
| Missouri | +11% | 2004 | 11 |
| Montana | +400% | 1979 | 40 |
| Nebraska | -49% | 1980 | 24 |
| Nevada | -80% | 1978 | 9 |
| New Hampshire | -6% | 1982 | 12 |
| New Jersey | +145% | 1981 | 24 |
| New Mexico | -10% | 1994 | 5 |
| New York | +267% | 1987 | 25 |
| North Carolina | +147% | 1979 | 40 |
| North Dakota | +686% | 1970 | 42 |
| Ohio | +59% | 1997 | 11 |
| Oklahoma | +720% | 1990 | 12 |
| Oregon | -72% | 1971 | 23 |
| Pennsylvania | -1% | 1991 | 31 |
| Rhode Island | +179% | 1985 | 5 |
| South Carolina | +50% | 1995 | 11 |
| South Dakota | +8% | 1969 | 33 |
| Tennessee | +431% | 1997 | 19 |
| Texas | +695% | 1975 | 57 |
| Utah | -81% | 1985 | 15 |
| Vermont | -42% | 1991 | 5 |
| Virginia | -21% | 1985 | 20 |
| Washington | -7% | 1976 | 38 |
| West Virginia | insufficient data | n/a | 4 |
| Wisconsin | +77% | 1978 | 41 |
| Wyoming | +14% | 1978 | 38 |
Double-crested Cormorant Population Trend by Region
Bird Conservation Regions are the ecological unit for trends.
| Northern Pacific Rainforest | +19% | 1971 | 38 |
| Great Basin | +7% | 1971 | 75 |
| Northern Rockies | -5% | 1983 | 44 |
| Prairie Potholes | +235% | 1969 | 86 |
| Boreal Hardwood Transition | -78% | 1982 | 33 |
| Lower Great Lakes / St. Lawrence Plain | +216% | 1990 | 22 |
| Atlantic Northern Forest | +93% | 1971 | 50 |
| Southern Rockies / Colorado Plateau | 13× | 1978 | 25 |
| Badlands and Prairies | 12× | 1969 | 54 |
| Shortgrass Prairie | +308% | 1987 | 22 |
| Central Mixed Grass Prairie | +981% | 1974 | 32 |
| Oaks and Prairies | -52% | 1982 | 22 |
| Eastern Tallgrass Prairie | +859% | 1982 | 79 |
| Prairie Hardwood Transition | +302% | 1975 | 59 |
| Central Hardwoods | 45× | 1996 | 27 |
| West Gulf Coastal Plain / Ouachitas | -47% | 1981 | 18 |
| Mississippi Alluvial Valley | +981% | 1993 | 27 |
| Southeastern Coastal Plain | 16× | 1969 | 113 |
| Appalachian Mountains | 14× | 1988 | 63 |
| Piedmont | -0% | 1987 | 40 |
| New England / Mid-Atlantic Coast | 25× | 1970 | 111 |
| Peninsular Florida | -95% | 1968 | 70 |
| Coastal California | +599% | 1974 | 40 |
| Sonoran and Mojave Deserts | -34% | 1979 | 16 |
| Sierra Madre Occidental | -43% | 1993 | 5 |
| Chihuahuan Desert | +106% | 1996 | 6 |
| Gulf Coastal Prairie | +101% | 1975 | 26 |
Double-crested Cormorant Conservation Status
Our route-weighted index shows it up about 177% 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.