How Long Do Squirrels Live? Squirrel Lifespan in the Wild

Squirrel lifespan at a glance

These figures are averages and records from many studies; individual squirrels vary widely.

Why do so many squirrels die young?

The first year is by far the most dangerous. Only about one in four gray squirrels survives to its first birthday. For the Eurasian red squirrel, around 75–85% of young die in their first winter.

Young squirrels face a series of hazards. They leave the nest at about 10–12 weeks old with little experience, and then must find a home range of their own, often crossing roads and open ground where predators wait. They have only a few months to learn which trees produce food, to bury nuts and to build up fat before the first winter.

Food supply is the biggest single factor. Oaks, beeches and hickories produce huge crops of nuts in some years, called mast years, and very few in others. After a good mast year many young squirrels survive; after a poor one, many starve or weaken during late winter and spring.

Survival after the first year

Once a squirrel has made it through its first year, its chances improve. In gray squirrels, mortality in the second year is still around 55%, but it then drops to about 30% a year for older adults, until it rises sharply again at around eight years old.

For red squirrels, an animal that survives its first winter has a life expectancy of about three more years. A few reach seven in the wild. As with grays, red squirrel survival rises and falls with the supply of tree seeds in autumn and winter.

What kills squirrels in the wild?

Squirrels have many predators. In North America, gray squirrels are hunted by hawks such as the red-tailed hawk, by owls, snakes, foxes, bobcats, weasels and raccoons. In Europe, red squirrels are taken by pine martens, goshawks, buzzards, owls, wildcats and foxes, and stoats raid nests for young.

In towns and suburbs, cars and domestic cats are major causes of death. Squirrels often freeze and then dart in the wrong direction when a car approaches, and roads are a leading cause of death for urban squirrels.

Disease also plays a part. Squirrelpox virus is usually fatal to red squirrels while rarely harming the gray squirrels that carry it, which is one reason red squirrels have declined so sharply in Britain. The story is covered in why are red squirrels declining?

Why do squirrels live longer in captivity?

In zoos and wildlife centers, squirrels are protected from predators, traffic, food shortages and harsh weather, so they can approach the natural limit of their bodies. Captive gray squirrels have reached about 20 years, roughly three times the age that a lucky wild adult attains. Red squirrels have lived to about 10 years in captivity.

This gap is typical of small mammals. Their bodies could last much longer, but in the wild few individuals live long enough to grow old.

Do larger squirrels live longer?

Within the squirrel family, larger species and those that hibernate tend to live longer. The eastern gray squirrel, at 400–600 g (14–21 oz), outlives the smaller red squirrel at 250–340 g (9–12 oz), on average. Marmots and some ground squirrels, which spend months each year in hibernation, can live considerably longer than tree squirrels of similar size.

Eastern chipmunks, small members of the squirrel family, usually live two to three years in the wild.

How do scientists know how old squirrels get?

Most of what we know comes from long-term field studies in which squirrels are caught, given a small numbered ear tag or microchip, released and then recorded again over the years. When a tagged squirrel is first caught as a juvenile, researchers know its age exactly, so repeated sightings show how long individuals survive and how many die each year.

For squirrels found dead, age can be estimated from the wear on the cheek teeth or from the dry weight of the eye lens, which keeps growing slowly throughout life. These methods give approximate ages and work best for separating young animals from older adults. Captive records come from zoos and wildlife parks, where the birth date of each animal is known.

How squirrels make up for short lives

Short lives are balanced by fast breeding. Female gray squirrels can start breeding at about one year old, give birth to litters of usually one to four young, and may raise two litters a year when food is plentiful. Red squirrels breed in the same way. This allows squirrel populations to bounce back quickly after a bad winter, even though most individuals live only a few years.