Roof rats can be a major problem particularly in larger, built up areas. They are omnivorous and feed on a range of stored food products, grains, cereals etc. however they are known to prefer vegetable and fruit matter. The roof rat does not tend to burrow, but is a skilled climber, making it able to nest in the high up roof cavities, wall cavities and the upper parts of tall warehouses and other buildings. They are also often a problem on ships and in buildings around sea ports.