Mice can be found in almost every type of habitat around the world, with the exception of Antarctica. In several locales, however, the animals are not native, but were rather introduced by humans. Generally nocturnal in nature, mice are primarily terrestrial creatures, although many are good climbers and swimmers. Diet varies somewhat by species, but most consume, seeds, insects, vegetation, and just about anything else they come across that is digestible. Prolific breeders, many mice reproduce throughout the year, although it is a seasonal occurrence in some species.