Water voles are herbivores, feeding on a huge variety of waterside vegetation (2), and consume 80 percent of their body weight each day (5). Their burrow systems have several horizontal layers to guard against flooding (5), and there is usually an underwater entrance to provide this strong swimmer with a safe route in and out (2). Above-water entrances to the burrow can often be identified by a 'lawn' of cropped grass around the hole (2). During the breeding season, the boundaries of female's ranges are marked with latrines, piles of flattened droppings where scent marking occurs. Each year between April and September, one to five litters consisting of three to seven blind, naked pups can be produced. Occasionally, dominant daughters may oust their mother from her territory after bouts of teeth chattering, tail beating and even boxing with the forefeet. In winter, a female, her daughters and unrelated males share a communal nest, but they do not hibernate (7).