Minnesota Profile: Double-Crested Cormorant (Phalacrocorax auritus)
This is the bird people love to hate. With the sinister look of a vulture, it sits in dead trees with wings outspread. Watching cormorants on a lake, folks assume that every dive wipes out a walleye.
The size of a small goose, it is 29 to 36 inches from bill to tail, and its wingspread may reach 54 inches. It has a long, thick neck; stout body; short, rounded wings; and medium-length tail with stiff feathers. Its legs are positioned far back on its body to aid in swimming. Flying in V-shaped flocks, the cormorant alternately flaps and glides. While perched or swimming, it usually tilts its bill upward.
Plentiful statewide in the late 1800s and early 1900s, they had large colonies at Heron Lake, Lake Shetek, Loon Lake in Jackson County, Lake of the Woods, and Lake Minnetonka. In 1926 people saw hundreds of thousands migrating north along the Mississippi River.
Because of misperceptions that cormorants "wipe out" game fish, sportsmen's clubs routinely killed nesting birds. By 1925 only about 1,000 cormorants nested in the state. Summer killings continued until the late 1950s, when protection was provided on state wildlife areas and enforcement of federal migratory bird laws improved.
The population soared in the 1980s as the birds established new colonies statewide. By the early '90s, Minnesota may have had 14,000 pairs. An outbreak of Newcastle disease reduced the population. Recent counts suggest a statewide population of 8,000 to 10,000 nesting pairs.
In Minnesota cormorants eat brook stickleback, logperch, yellow perch, sunfish, cisco, white suckers, black bullheads, white crappies, crayfish, northern pike, walleyes, and tiger salamanders. One study revealed that 90 percent of the fish eaten were 5.3 inches or shorter. A Canadian study showed that walleyes and northern pike together made up less than 1 percent of the cormorant's diet.
Bait dealers lose minnows because shallow rearing ponds are ideal places for cormorants to feed. A recent federal law allows operators of commercial aquaculture facilities in Minnesota and 11 other states to shoot cormorants that threaten their stocks. This policy has reduced animosity, but the cormorant is still a bird of low esteem.