Common transient; accidental summer (breeding) resident; rare summer visitor; rare winter resident
Length: 32 inches
It’s common to find these big birds congregated on a submerged snag, wings outstretched, catching the sun’s rays. They get their signature double crest from a pair of tufts located behind the eyes, which only appear during breeding season. Adult cormorants are black with an orange skin pouch below their long, hook-tipped bill. Immatures are brownish with a whitish breast.
Mated pairs build nests, measuring 1–3 feet wide, of sticks and grass on the ground, on rocks, or in treetops. Nests are typically built near other pairs in breeding colonies. Females lay one to seven eggs, which hatch in 25–28 days. The young leave the nest three to four weeks later. There are one or two broods annually.
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 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.
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.
Cormorants have not always been well regarded amongst humans. Historically, humans viewed the birds as competition for game fish, and until the early 1900s, shot and persecuted them, causing population declines. Then in the 1950s, pesticide use further reduced populations. Their numbers have rebounded, but some still regard them as pests.
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