...many types of rodents, and so many of each type. They are at the bottom of the mammal food chain, pretty much, with everything from birds and spiders to coyotes and skunks using them as food.

Plus, not only are there literally 1,000's of types of mice and rats, but also capybaras, chinchillas, voles, lemmings, porcupines, beavers, woodchucks, gophers, guinea pigs, hamsters, gerbils, and so forth.