Characteristics of Commensal Rodents
A quick at a glance chart of the differences between mice and rats
Roof Rats
- Characteristic: Sleek, graceful
- Adult size: 5-9oz/150-250g
- Length: (nose to tip of tail):6-8 in/16-20cm
- Snout: Pointed
- Ears: Large, nearly naked;can be pulled over eyes
- Eyes: Large, prominent
- Tail: Uniformly dark
- Fur: Gray to black ; abdomen, gray, or black; smooth
- Droppings: Spindle shaped, 1 cm/0.5 inch
- Senses:
- Sight: Poor,color blind
- Smell, Taste, Touch, Hearing: Excellent
- Food: Omnivourous, especially fruits, nuts,grains, and vegetable (15-30 grams/day) 0.5-1.0 oz/day
- Water: 15-30 ml/day
- Feeding Habits: Shy (new object reaction);steady eater
- Climbing: Very agile, active climber
- Nests: Walls, attics, vines, trees;sometimes burrows
- Swimming: Can swim
- Home Range Radius: 30-50 m/98-164 ft.
- Age at mating (months): 2-3
- Breeding season: Spring and Fall peaks
- Gestation period (days): 22
- Young per litter: 4-8
- Litters per year: 4-6
- Young weaned/female/year: 20
- Length of life: 1 year
Norway Rats
- Characteristic: Large, robust
- Adult size: 7-18oz/200-500g
- Length: ((nose to tip of tail): 7-9.5in/18-25cm
- Snout: Blunt
- Ears: Small, covered with short hairs; do not reach eyes
- Eyes: Small
- Tail: Dark above, pale beneath
- Fur: Brown with scattered black; abdomen -gray to yellow-white;shaggy
- Droppings: Capsule shaped, 2cm/3/4-1 inch
- Senses:
- Sight: Poor,color blind
- Smell, Taste, Touch, Hearing: Excellent
- Food: Omnivorous(22-30grams/day) 0.8-1 oz.
- Water: 15-30 ml/day
- Feeding Habits: Shy (new object reaction);steady eater
- Climbing: Readily climbs, limited agility
- Nests: Usually burrows
- Swimming: Excellent swimmer
- Home Range Radius: 30-50 m/98-164 ft.
- Age at mating (months): 2-3
- Breeding season: Spring and Fall peaks
- Gestation period (days): 22
- Young per litter: 8-12
- Litters per year: 4-7
- Young weaned/female/year: 20
- Length of life: 1 year
House Mouse
- Characteristic: Small, Slender
- Adult size: 0.4-1 oz/12-30 g
- Length:(nose to tip of tail):2-3.5 in/6-9cm
- Snout: Pointed
- Ears:
- Eyes: Small
- Tail: Uniformly dark
- Fur: Light brown, light gray; smooth
- Droppings: Rod shaped, 3-6 mm/0.5 inch
- Senses:
- Sight: Poor,color blind
- Smell, Taste, Touch, Hearing: Excellent
- Food: Omnivourous, prefers cereal grains(3 grams/day) 0.1 oz. day
- Water: 3-9 ml/day;can subsist without water
- Feeding Habits: Inquisitive, nibbler
- Climbing: Good climber
- Nests: Within structures, stored food; burrows
- Swimming: Can Swim
- Home Range Radius: 3-10m/10-33 ft.
- Age at mating (months): 2-3
- Breeding season: Year long
- Gestation period (days): 19
- Young per litter: 4-7
- Litters per year: 8
- Young weaned/female/year: 30-35
- Length of life: 1 year
* From Truman's Scientific Guide Sixth Edition
Note: Data are averages and not representative of extremes.
Sources: Compiled from J.E. Brooks and F.P. Rowe, Commensal Rodent Control(World Health Organization,WHO/VBC/79.726, Geneva,1979);W.E. Howard and R.E. Marsh, The Rat:Its Biology and Control(Univ.of California, Division of Agriculture Sciences, leaflet no 2,896,1976); H.D. Pratt and R. Z. Brown, Biological Factors in Domestic Rodent Control( U.S. Department of Health, Education and Welfare , Centers fo Disease Control, bulletin no 76-8144, 1976);R. E. Marsh and W.E. Howard, The House Mouse: Its Biology and Control(University of California, Division of Agricultural Sciences, leaflet no. 2,945, 1977);W.B Jackson, "Norway Rats and Allies," in Wild Mammals of North America, ed J.A. Chapman and G. A.Feldhamer(Baltimore: Johns Hopkins University Press, 1982)
