ODNR Division of Wildlife - A to Z Species Guide - Double-crested Cormorant

Double-crested Cormorant

Double-crested cormorants last nested in the state in the 1880s and were reduced to migrant status until the 1990s, when they began nesting in the Lake Erie region. Cormorants have rapidly increased in the Western Basin of Lake Erie as both a breeder and as a migrant. West Sister Island NWR makes up the largest colony and has shown continued long-term growth. The banning of DDT and other persistent pesticides is believed to be responsible for the resurgence of double-crested cormorant populations.

Double-crested Cormorant

Phalacrocorax auritus

At-a-Glance

• Mating: Monogamous

• Peak breeding activity: between April and August, with peak activity occurring in May through July.

• Incubation period: 25 - 28 days

• Clutch Size: 1-7 eggs; 4 average • Typical Foods: fish

Description
These birds are large, with dark brown or black plumage that has a dull green sheen. They have long necks with throat pouches and the long, yellow-orange beak is hooked at the tip.

Habitat and Habits
Cormorants inhabit lakes, ponds, marshes, and the open waters of Lake Erie. They are mostly silent, but can produce low croaks and grunts.

Reproduction and Care of the Young
Double-crested cormorant nests are platforms composed of sticks and placed in large trees adjacent to large bodies of water. They may nest with herons in mixed colonies or by themselves in segregated colonies. Most nesting occurs in June and July and most young cormorants are expected to leave their colonies between mid-July and mid-August.