Table I Characteristics of commensal rodents

Characteristic

Norway Rat

Roof Rat

House Mouse

General Appearance

Large, robust

Sleek, graceful

Small, Slender

Adult size
weight(oz/g)

length(nose to tip of tail)

head and body(mm)
tail(mm)

7-18oz/200-500g

7-9.5in/18-25cm

6-8 in/15-21cm

5-9oz/150-250g

6-8 in/16-20cm

7-10in/19-25cm

0.4-1 oz/12-30 g

2-3.5 in/6-9cm

3-4in/7-10cm

Snout

Blunt

Pointed

Pointed

Ears

Small, covered with short hairs;do not reach eyes

Large, nearly naked;can be pulled over eyes

Large, some hair

Eyes

Small

Large, prominent

Small

Tail

Dark above, pale beneath

Uniformly dark

Uniformly dark

Fur

Brown with scattered black; abdomen -gray to yellow-white;shaggy

Gray to black ; abdomen, gray, or black;smooth

Light brown, light gray; smooth

Droppings

Capsule shaped, 2cm/3/4-1 inch

Spindle shaped, 1 cm/0.5 inch

Rod shaped, 3-6 mm/0.5 inch

Senses
sight smell, tast, touch, hearing

Poor, color blind
Excellent

Poor, color blind
Excellent

Poor, color blind
Excellent

Food

Omnivorous(22-30grams/day)
0.8-1 oz.

Omnivourous, especially fruits, nuts, grains, and vegetable
(15-30 grams/day) 0.5-1.0 oz/day

Omnivourous, prefers cereal grains(3 grams/day) 0.1 oz. day

Water

15-30 ml/day

15-30 ml/day

3-9 ml/day;can subsist without water

Feeding habits

Shy(new object reaction);steady eater

Shy(new object reaction);steady eater

Inquisitive, nibbler

Climbing

Readily climbslimited agility

Very agile, active climber

Good climber

Nests

Usually burrows

Walls, attics, vines, trees; sometimes burrows

Within structures, stored food; burrows

Swimming

Excellent swimmer

Can swim

Can Swim

Home range radius

30-50 m/98-164 ft.

30-50 m/98-164 ft.

3-10m/10-33 ft.

Age at mating(months)

2-3

2-3

2-3

Breeding season

Spring and fall peaks

Spring and fall peaks

Year long

Gestation period(days)

22

22

19

Young per litter

8-12

4-8

4-7

Litters per year

4-7

4-6

8

Young weaned/female/year

20

20

30-35

Length of life

1 year

1 year

1 year