What is the difference between a Rat and a Mouse?

Before we delve into the differences, both the brown rat and house mouse are classed as rodents, but what is a rodent? A rodent is a small mammal with constantly growing incisor teeth used for gnawing, this includes, rats, mice, squirrels and the largest rodent, the capybara. Rodent comes from Latin to mean “to gnaw” or “one who gnaws” . The Norway rat and house mice gnaw to keep their teeth healthy and short, materials such as wood, plastic and most commonly electrical wiring are gnawed by rodents.

Norway rat (rattus Norvegicus)

The Norway rat has a thick body and short hairs, usually weigh around 200g to 500g, droppings are considerably larger than mice, around 10mm to 20mm. The brown rat tends to communicate via pheromones in their urine such as potential dangers or ready to mate, their urine is quite pungent and acrid. Rats tend to burrow down into soil or or in loft insulation for warmth, typical burrow hole size is around the size of a tennis ball. Rats tend to favour cereal or seed based food exclusively but can feed on other types of food stuff if available, a constant water source is also required for rats to survive. Rats suffer from Neophobia, a fear of new objects, whether this be a change in the environment or new items placed in areas of harbourage. Unlike mice, rats deposit their droppings in what is know as a “latrine”, or toilet area. They become sexually mature at around 12 to 16 weeks and gestation period of around 3 weeks, usually giving birth to around 6-12 young pups.

Character Traits; 

• Thick body
• Small Ears
• Thick Hairless Tail – shorter than body
• Large Feet
• Blunt Nose
• Large Droppings – Similar size to sunflower seed, rounded edges 10mm-20mm
• Neophobic (fear of new objects)
• Squeezes through gaps as little as 20mm

House mouse (mus musculus)

The house mouse is a much smaller rodent, with a slimmer body and weighing around 15g to 18g. Typical nesting sites are in and around the home, such as loft spaces and wall cavities. Average size of mouse droppings are around the size of a grain of rice, mice tend to leave droppings around perimeter of rooms of nesting sites. Mice are quite territorial and will mark this by creating urine pillars to assert their dominance. Mice are sexually mature at around 5 weeks of age, gestation period similar to that of rats, around 3 weeks, and have an average litter size of 8-12. Mice tend to prefer cereal based foods, and will tend to strip the husks of seeds to expose the endosperm. Mice don’t need a constant fresh water source and will naturally acquire this from the foods they eat.

Character Traits;

• Slender body
• Large Ears
• Thin, long tail with hairs, around 80% length of its body
• Small feet
• Pointy Nose
• Smaller droppings, pointy ends, around 1-2mm, about the size of a grain of rice
• Inquisitive in nature
• Squeezes through gaps as little as 5mm

While both are different in appearances, one similarity both the House `Mouse and Norway rat share in common, is that they are commensal rodents (to share ones table), due to their closeness to humans.