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Double-Crested Cormorant

Phalacrocorax auritus
Family: 
Phalacrocoracidae (cormorants) in the order Pelicaniformes
Description: 

Adults are black with an orange skin pouch below a long, hook-tipped bill. Immatures are brownish with a whitish breast. Frequently observed in large numbers sitting upright on snags over water, sometimes with wings outstretched. The “double crest” is a pair of tufts behind the eyes that this species acquires only during breeding season.

Similar species: Cormorants can be confused with anhingas when soaring. In flight, the latter may be distinguished by its longer, fanned-out, squared-off tail. At rest, anhingas have a “snakier” neck than cormorants do. Anhingas have a pointed bill that is not hook-tipped. The anhinga is a casual transient and summer visitor that formerly bred in Pemiscot and Dunklin counties. Irregularly seen from late April through mid-September.

Size: 
Length: 32 inches (tip of bill to tip of tail).
Habitat and conservation: 
Common migrant on lakes and rivers. Currently breeds some years along the Mississippi River. Historically, breeding colonies were located in the Mississippi Lowlands until 1956. Cormorant numbers dropped during the years of DDT but have risen in the Midwest, at least in part, due to habitat changes and introduced species. Numbers have risen remarkably in the Great Lakes, where fishermen claim they compete for game fish, and where their roosting colonies create enough guano to kill island trees.
Foods: 
Cormorants dive underwater for fish, surfacing on occasion but remaining submerged except for the neck and head. To decrease buoyancy and facilitate underwater swimming, cormorants’ feathers have few of the oils that repel water, so they become soaked as the bird swims. This is why cormorants typically stand with wings outstretched: They are allowing their feathers to dry.
Distribution in Missouri: 
Statewide.
Status: 
Common transient; accidental summer (breeding) resident; rare summer visitor; rare winter resident.
Life cycle: 
Nests are constructed on the ground, on rocks, or in treetops by both partners and are built of sticks and lined with grass. Nests are 1-3 feet wide and are typically built near those of other pairs in breeding colonies. Clutches comprise 1-7 eggs, which hatch in 25-28 days. The young leave the nest about 3 or 4 weeks later. There are 1 or 2 broods annually.
Human connections: 
Humans have historically viewed cormorants as competitors for game fish and, until the early 1900s, shot and persecuted them, causing populations to decline. In about the 1950s, pesticides further reduced their populations. Their numbers have rebounded, but many still view them as pests.
Ecosystem connections: 
Cormorant numbers in Lake Erie are linked to the presence of the invasive zebra mussel, a filter feeder that clarifies water, which helps cormorants hunt fish easier. Also, less plankton means fewer small fish, reducing fish numbers overall and increasing competition between people and cormorants.
Shortened URL
http://mdc.mo.gov/node/19993