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Squirrels & Wildlife

Are Squirrels and Rats Related? Rodent Cousins, Not Kin

Squirrels and rats are both rodents but sit in separate families that split over 60 million years ago. What they share, and how differently they behave.

By Zakaria 2 min read Save to Pinterest — opens Pinterest in a new tab
A brown rat feeding on spilled birdseed on a rock
Photo: wolfgangvogt_lb, Pixabay Content License, via Pixabay
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They are related, but about as closely as a cat is to a dog — same order, different families, roughly 60 million years apart.

Where each one sits

levelsquirrelrat
OrderRodentiaRodentia
FamilySciuridaeMuridae
Typical genusSciurusRattus
Split—~60 million years ago

What they genuinely share

  • Ever-growing incisors in both jaws, which must be worn down — hence chewing wood, cable and plastic trim
  • A gnawing jaw structure that is the defining rodent adaptation
  • High reproductive rate relative to body size
  • Opportunism around human food sources

Where they diverge

  • Daily cycle. Squirrels are diurnal; rats are largely nocturnal. If something is raiding the bird feeder at noon it is not a rat
  • Diet. Squirrels specialise in nuts and seeds and cache for winter. Rats are omnivorous generalists
  • Habitat. Tree canopies and lofts against ground burrows and wall voids
  • Anatomy. Bushy tail, large eyes and prominent ears against a thin scaly tail and lower ears

Why the fluffy-tailed-rat line persists

Both gnaw, both get into buildings, both are rodents. The resemblance is a shared order-level trait, not close kinship — the same reason a hedgehog and a mole look alike without being related.

The practical difference in a yard

  • Squirrel signs: daytime activity, raided feeders, dug bulbs, bark stripped in spring, noise in the loft during the day
  • Rat signs: droppings in runs, burrows with fanned soil, night activity, gnawed feed bins, damage low down and near the house

The second list is the one to act on quickly.

Common questions

Are squirrels and rats related?

Distantly. Both are rodents, which makes them cousins within the same order, but they belong to different families — squirrels to Sciuridae and rats to Muridae — and those lineages separated something in the order of 60 million years ago. For comparison, that is a wider gap than the one between cats and dogs. So the popular line that a squirrel is just a rat with a fluffy tail is wrong in the same way as calling a dog a cat with a different coat.

Is a squirrel a rodent?

Yes. Squirrels are members of Rodentia, which they share with rats, mice, beavers, porcupines, voles and guinea pigs. The defining rodent feature is a single pair of continuously growing incisors in each jaw, kept in check by gnawing. That is what squirrels and rats genuinely have in common, and it explains why both chew wood, wiring and plastic.

What are the main differences between squirrels and rats?

Activity cycle, diet and habitat. Squirrels are diurnal, active in daylight and asleep at night; rats are mostly nocturnal. Squirrels are primarily tree-dwelling seed and nut specialists that cache food; rats are ground-living generalists that eat almost anything and do not cache in the same way. Squirrels have bushy tails, larger eyes and visible ears; rats have sparse scaly tails and lower-set ears.

Do squirrels carry the same diseases as rats?

Not the same profile. Rats are associated with leptospirosis, salmonella, hantavirus in some regions and the historical plague vector role through their fleas. Squirrels carry fewer human-relevant pathogens; their issues are mainly fleas, mites, ticks and roundworm, with occasional leptospirosis. Neither is a notable rabies risk — rodents very rarely transmit it. Either way, do not handle a wild one, and treat any bite as needing medical advice.

Can squirrels and rats interbreed?

No. The two are in different families with different chromosome counts and tens of millions of years of separate evolution — there is no possibility of hybrid offspring. Animals that look like a cross between the two, such as some ground squirrels or marmots, are simply other squirrel-family species with short tails.

Which is the bigger pest in a garden?

They cause different damage. Squirrels take nuts, fruit, bulbs and bird seed, and strip bark in spring; they get into lofts and chew through insulation and cable. Rats do more serious damage closer to the house, contaminate stored feed, burrow under structures, and are the greater public-health concern. Squirrel damage is usually annoying; established rat activity is worth acting on quickly.

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