CRUSTACEANS ON THE MENU
I went for a short walk with my camera to the Jiloca River behind our house in Calamocha, Teruel, Spain. It is so close that I sometimes go by myself, trying to spot birds or lizards on the stone walls of the orchards. This time, I saw a wren by the water. Following it with my lens, I observed unusual behaviour – it popped its head underneath the water’s surface. The bird repeated this several times. When I got home and saw the pictures on the computer, I realised that it had preyed on an amphipod. This is the first time I have seen this behaviour, is it common for wrens to fish? BTO Ornithologist Viola Ross-Smith replies: While many people rightly think of wrens as terrestrial insect eaters, it’s not unheard of for these tiny birds to consume a wider variety of prey, including from aquatic environments. Freshwater crustaceans, especially Gammarus pulex, are sometimes consumed, and wrens have even been recorded eating tadpoles and young frogs, which they will break apart to feed to fledglings, and small fish (minnows, for example) and their fry. Wrens will normally take aquatic prey from the water’s surface, but are known to enter the water sometimes, immersing their heads – and on rare occasions even their whole bodies – in pursuit of a meal. Amazing!