A mouse and a rat are both small rodents, but they are different species with clear distinctions in size, appearance, behavior, and the ways they interact with humans. Knowing the difference helps identify which pest you're dealing with — the control approach differs significantly.

The Fastest Way to Tell Them Apart: Droppings

This is the most reliable identification method without seeing the animal directly:

• Mouse droppings: 3–6mm, rice-grain shaped with pointed ends
• Rat droppings: 12–20mm, capsule-shaped with blunt ends

This single observation is usually enough to identify which pest you have and determines what traps and bait sizes to use.

Physical Differences

• Size: Mice are 6–10cm long (not counting the tail); rats are 15–23cm with a much thicker body
• Head: Mice have small, triangular heads with a pointed snout; rats have larger, blunter heads
• Ears: Mice have large ears relative to their head; rats have proportionally smaller ears
• Tail: Mouse tails are long, thin, and slightly hairy; rat tails are shorter relative to body size, thick, and mostly hairless with a scaly appearance
• Feet and teeth: Rats have bigger feet and thicker teeth — they gnaw through tougher materials

Behavioral Differences

• Mice are curious and explore new things quickly; rats are cautious and suspicious of changes (neophobia)
• Mice nibble small amounts in many places; rats eat more and may store food
• Mice nest close to food sources inside walls and cupboards; rats burrow underground or in ground-level structures
• Rats are more intelligent and can learn trap avoidance over time; mice are more impulsive

Which Species Are Common in New Hampshire?

In New Hampshire, Norway rats (brown rats) and house mice are the two most common species:

• Norway rats are most common in basements, crawl spaces, and near water
• House mice are most common in kitchens, wall voids, and pantries

If you're dealing with a larger, ground-level pest, it's most likely a Norway rat. If it's small and found near food storage, it's likely a house mouse.

Why It Matters for Control

Trap sizes, bait amounts, placement height, and pre-baiting requirements all differ between mice and rats. Using mouse traps for rats (or vice versa) is one of the most common reasons DIY control fails. See our specific guides for mouse traps and rat traps for the right approach.