Breeding occurs mostly in spring and fall. Because of their high reproductive rates and ability toinvade many habitats, rodents are able to spread and multiply quickly. Population, however, may soon crash because of predation, disease and foodshortages. Archaeological record shows that rodents were present even 58 million yearsago. These animals, however, diversified into leaping, running andburrowing forms between 54 and 38 million years ago.
Most rodents eat a wide range of plant material as wellas invertebrates.
A few are specialized carnivores. Most rodentshave a little contact with humans. Nevertheless, some species likerats and mice are pests in houses, agricultural crops, and food storage. Rodent pests can transmit more than 20 pathogens to humans. The bubonicplague was responsible for the death of 25 million people just in Europein the 14-17th centuries.