Cormorants are often seen gulping down large fish at the water’s surface, even when they’ve been foraging in murky waters, yet researchers at Birmingham have recently shown that the visual acuity of these birds underwater is rather poor, similar in fact to our own. Might a system other than vision help explain the huge success of these birds as underwater predators? One possibility is that cormorants are able to detect the small electrical fields associated with potential prey items. Many species of fish use electroreception, as well as the duck billed platypus and the echidnas. In order to try and ascertain whether or not cormorants can too, Emily Shepard came from Swansea University to collaborate with Pat Butler and run some experiments using a set-up developed by Graham Martin to test the cormorants’ visual acuity. By rewarding cormorants with a fish every time they swam through a choice-channel and selected the side with the electrical current, they hoped to learn whether or not these birds could associate an electrical cue with a reward. So far it seems that if the cormorants can detect electrical currents they’re keeping it close to their chests!
