Phalacrocorax auritus

After hundreds of studies, it has been difficult to link fish predation by cormorants (Phalacrocorax auritus) to the reduction of fishing quality in Minnesota lakes. It appears that game fish such as walleye and northern pike make up from less than 1% to nearly 3% of the bird's diet. They eat only small fish. Many of the fish they eat are perch, which prey on walleye, and it is even possible that by culling small walleye or northerns, they increase the growth rate for those fish in two way. One is by reducing competition between fish for food, and the other is by exerting selective pressure…
tags: Double-Crested Cormorant, Phalacrocorax auritus, birds, mystery bird, bird ID quiz [Mystery bird] Double-Crested Cormorant, Phalacrocorax auritus, photographed at Hermann Park, Houston, Texas. [I will identify this bird for you in 48 hours] Image: Joseph Kennedy, 23 December 2009 [larger view]. Nikon D200, Kowa 883 telescope with TSN-PZ camera eyepiece 1/500s f/8.0 at 1000.0mm iso400. Please name at least one field mark that supports your identification. Review all mystery birds to date.
tags: Double-crested Cormorant, Phalacrocorax auritus, birds, mystery bird, bird ID quiz [Mystery bird] Double-crested Cormorant, Phalacrocorax auritus, photographed at Whittier Narrows, California. [I will identify this bird for you in 48 hours] Image: Steve Duncan, 8 December 2009 [larger view]. Nikon D200 w/ Nikkor 300mm f/4 & TC17E. Please name at least one field mark that supports your identification. Review all mystery birds to date.