Rattus norveglcus. Also called "common rat", "water rat", "brown rat", or "sewer rat".Description: Brownish gray above; grayish below. Up to 18 inches long including tail.Its thick, scaly tail is shorter than head and body combined. Small eyes and hairy ears. Weighs 7 to 17 oz.Habitat: Farms, cultivated fields, sewers, warehouses, or other human dwelling places throughout the U.S.Characteristics: Agile climber. Good swimmer. Uses sensitive whiskers to navigate. Feeds at night. Daytime feeding indicates large population. Its powerful incisors continuously grow; rats maintain them by gnawing through objects such as wood, electrical cables and pipes. Overpopulation produces mass migration. Burrows for nesting and feeding. Suspicious and wary.Reproductive Cycle: Females mature sexually at 3 months. Gestation lasts 3 weeks.Can bear up to 12 litters annually but usually 5 litters of 7-11 young.Food Preferences: Stored cereals, meat, insects, wild plants, seeds, chicken eggs and young poultry.
Rattus rattus. Also called "ship rat".Description: Dark brownish with gray belly. Averages 15 inches in length - somewhat smaller than the Norway rat. Slender tail is longer than head and body combined. Large almost hairless ears. Weighs up to 9 oz. Habitat: Upper floors of buildings, trees, and lush vegetation (often in exclusive well-landscaped yards), seaports and ships. Abundant in South and along Atlantic, Gulf and Pacific coasts. Characteristics: Extremely agile.Expert climber. Can also gnaw through wood, lead piping and electrical cables. Builds nests above ground,often in trees and tangled vines. Carrier of the "Black Plague" that killed millions of people in the14th century. Reproductive Cycle: Similar to Norway Rat. Breeds throughout the year, producing several litters of 2-8 young.Food Preferences: Cereals, grains, nuts, fruits.
Mus musculus. Description: Grayish brown above and somewhat lighter underneath. From 5 to 7-3/4 inches long. Weighs from 5/8 to 3/4 oz. Habitat: Buildings, cultivated fields, and areas near man with good ground cover. Characteristics: Nibbler. Inquisitive. Territorial - stays close to nest. Grooms frequently. Contaminates food with urine and small droppings. Chews or gnaws through walls, floors,baseboards or electrical cords which can start fires. Nests made of string, shredded paper, straw.Reproductive Cycle: Females can produce first litter at 8-10 weeks. Pregnancy lasts 3 weeks. Average7 to 10 litters per year with 4-16 young per litter. Females can conceive shortly after delivery.Food Preferences: Seeds, cereals, grains, and sweets.