Rat Damage Control to Round-Baled Silage by Modifying Storage Layout

This self-review summarizes the prevention of rat damage to wrapping film when whole-crop forage containing cereals is preserved as round-baled silage (RBS). A trapping survey at the RBS stock yards showed that Large Japanese field mice (Apodemus speciosus), Japanese grass voles (Microtus montebelli), brown rats (Rattus norvegicus), and roof rats (Rattus rattus) were species with the potential to inflict damage. The features of the damage differed for each rat species. In particular, it was observed that brown rats and roof rats tended to cause extensive film-damage. RBSs are usually stacked in close proximity because they are produced in bulk. This usual storage layout was considered to provide rats with many narrow spaces between RBS, inaccessible to most of their predators, thereby exacerbating the rat damage to RBS. When modifying the storage layout to produce open spaces between RBS by separating them, the modified layout was effective in preventing damage caused by brown rats and roof rats because the predation hazard would be increased. However, the effect was lost when the spaces between RBS were covered with snow or when species such as Large Japanese field mice damaged RBS's bottom from underground burrows. It was suggested that these problems may be resolvable by providing sufficient open space between RBS and protecting the bottom with wire netting.