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Squirrels & Wildlife

Are Squirrels From the Rat Family? Same Order, Not Family

Both are rodents and the resemblance stops there. Squirrels are Sciuridae, rats are Muridae — and the differences are practical, not academic.

By Zakaria 2 min read Save to Pinterest — opens Pinterest in a new tab
A brown rat among fallen autumn leaves
Photo: JonPauling, Pixabay Content License, via Pixabay
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Both are rodents. So are beavers, porcupines, guinea pigs and capybaras — the order is enormous, and sharing it means very little.

Where each sits

ranksquirrelrat
OrderRodentiaRodentia
FamilySciuridaeMuridae
GenusSciurusRattus
Also in the familychipmunks, marmots, prairie dogsmice, gerbils

Identifying which is in the roof

cluesquirrelrat
Time of noisedaylightafter dark
Soundheavy, rolling, draggingscurrying, scratching
Droppingslarger, rounded, scatteredsmaller, tapered, in runs
Entry gap needed4–5 cm~2 cm
Food storagecached outside, scatteredhoarded near the nest
Greasy smear marks on timbernoyes

The hour settles it

Tree squirrels are strictly diurnal and rats are nocturnal. Noise overhead at two in the morning is not a grey squirrel. The exception is flying squirrels, which are nocturnal — and need a far smaller gap, so sealing for greys will not exclude them.

Why the repair matters more than the eviction

A squirrel opens a 4–5 cm hole. Once it leaves, that opening is four times wider than a rat requires. Treating the squirrel as the problem and the hole as cosmetic is how one animal problem becomes a worse one — and rats bring the leptospirosis and contamination risks that squirrels largely do not.

  • Galvanised steel mesh, 12 mm or finer, screwed behind the damaged board
  • Not expanding foam, plastic mesh or chicken wire — all chewed through
  • Check the whole roofline, not just the hole you found
  • Watch at dawn before sealing, so nothing is shut inside

The insult is also ecologically wrong

“Tree rat” understates the difference. Squirrels are among the most effective seed dispersers in northern forests — much of the oak regeneration in their native range is planted by squirrels that failed to recover a cache. Rats do nothing comparable.

Common questions

Are squirrels in the rat family?

No. Both are rodents — order Rodentia — but they sit in different families and have done for tens of millions of years. Squirrels are Sciuridae, along with chipmunks, marmots, prairie dogs and flying squirrels. Rats and mice are Muridae. The shared features people notice, chiefly continuously growing incisors, are characteristics of the whole order rather than evidence of close kinship.

How closely related are they, really?

Distantly. The split between the squirrel lineage and the mouse-and-rat lineage is estimated at roughly 60 to 70 million years ago, near the base of the rodent radiation. For comparison, that is a wider gap than the one between dogs and bears. They are about as related as any two rodents can be while still both being rodents.

What are the practical differences?

Several that matter if something is in your roof. Squirrels are strictly diurnal and rats are nocturnal, so the time of the noise identifies the animal. Squirrel droppings are larger, rounded and scattered; rat droppings are smaller, tapered and concentrated in runs. Squirrels need a gap of about 4–5 cm, rats about 2 cm. And squirrels cache food while rats hoard it in one place near the nest.

Do squirrels carry the same diseases as rats?

Not the same profile. Squirrels are not significant reservoirs for leptospirosis in the way rats are, and rabies in tree squirrels is very rare. They do carry fleas, ticks and mites, and in parts of the western United States ground squirrels are associated with plague-carrying fleas. The main household risk from a squirrel is chewed wiring and nest material, not disease.

Why do people call grey squirrels tree rats?

Usually as an insult rather than a classification, and most often in Britain where greys are an invasive species displacing native reds. It is also used by gardeners who have lost bulbs or fruit. Taxonomically it is simply wrong — and ecologically it understates the difference, since squirrels are major seed dispersers that regenerate oak woodland, which rats are not.

Are squirrels and rats ever in the same roof space?

Yes, and often in sequence rather than together. A squirrel chews an opening of 4–5 cm, uses the space, and leaves or is excluded; the hole remains, and a rat needs only 2 cm. That is why a squirrel problem treated cosmetically becomes a rat problem later, and why the repair matters more than the eviction.

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