Several years ago a flock of cormorants arrived on the St. Joseph River near our home. The river was close to flood stage. The water was so muddy that you couldn’t see the bottom even if the water had been only an inch deep. Those birds demonstrated that cormorants find fish in muddy waters.
The birds landed in a large tree on an island in the middle of the river. Very soon after they landed, one took off and dove into the river. A minute or so later it came to the surface with a fish in its beak. For the rest of the day, we saw these fishing birds dive and catch fish, sometimes staying under water for a very long time. I wondered how they could do that because sight in the water was non-existent.
In the October/November 2017, issue of National Wildlife (page 8), there is an article explaining how cormorants and other fish-eating birds manage when the water is so loaded with mud that they can’t see. Scientists at the University of Southern Denmark have studied the hearing of the great cormorant. They discovered that this seabird has a specialized sense of hearing tuned to a very narrow frequency range. The frequency is the same as the sound produced by herring and sculpin fish as they swim in the water. Those fish are the primary prey of the cormorant and sculpin live on the bottom of water bodies where it is dark, and the water is often dirty.
There are over 800 species of birds that find their food underwater. Since these cormorants find fish in muddy waters, the scientists on this project predict that other aquatic birds also use specialized hearing to catch fish. We see this as another design that God gave these creatures for survival.
–John N. Clayton © 2017