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Life Cycle of Chipmunks: Birth to Burrow in One Year

Chipmunks are blind and hairless for a month, independent by eight weeks, and breeding by the next spring. Most never reach their second birthday.

By Zakaria 3 min read Save to Pinterest — opens Pinterest in a new tab
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Blind and hairless for a month, independent at eight weeks, breeding by the next spring — and most never see a second birthday.

The year, in order

Eastern chipmunk, typical timings
StageWhenWhat happens
First matingFeb–AprilMales range widely; brief, noisy chases
Gestation~31 days—
First litterApril–May4–5 young, blind, hairless, ~3 g
FurWeek 2—
Eyes openWeeks 4–5—
First emergence~Week 6Short trips near the entrance
Weaned, dispersing~Week 8Young dig their own burrows
Second matingJune–JulySmaller litter follows in late summer
CachingAug–OctCheek pouches, constant hoarding
TorporNov–MarWaking periodically to eat from the larder

They hoard instead of fattening

This is the detail that explains most chipmunk behaviour. Unlike a groundhog, a chipmunk does not lay down deep fat reserves and sleep through winter.

It enters torpor — body temperature and heart rate dropping for a few days at a time — then wakes to eat from food stored in the burrow, and relieves itself in a dedicated chamber before going back under.

That strategy requires a larder, which is why autumn is spent in relentless collection, and why cheek pouches that can hold a startling volume evolved at all. In mild spells they will come above ground in midwinter.

One burrow, one chipmunk

Chipmunks are solitary and territorial outside breeding. Each adult keeps its own tunnel system — up to around nine metres, with separate chambers for nesting, storage and waste.

A garden that seems to hold a colony is really a set of individual territories packed close together, often with several entrances each.

Why most die young

The average of two to three years sits well below the five or six a lucky individual reaches, and almost all of that gap is predation in the first year:

  • Hawks, especially during the exposed dispersal period
  • Domestic cats, which take very large numbers in suburban gardens
  • Snakes, which can enter burrows
  • Foxes, weasels and raccoons
  • Roads, during dispersal

A young chipmunk leaving its mother’s burrow at eight weeks to dig its own, in unfamiliar ground, is at its most vulnerable precisely when it is least experienced.

The lifespan question has its own page with the figures in full — see how long chipmunks live.

Garden implications

  • Spring chases across patios and fences are mating, not fighting
  • A sudden crowd in late summer is the second litter dispersing
  • Frantic autumn activity is larder building, not an infestation
  • Winter sightings are normal — they are not asleep for the season
  • Keeping cats in does more for local chipmunk survival than anything else

Common questions

How long do chipmunks live?

Two to three years in the wild is typical, though most never get that far — predation in the first year is heavy enough that a large share of any litter does not survive to breed. Individuals that establish a good burrow and avoid hawks, cats, snakes and foxes can reach five or six years, and captive chipmunks have lived past ten. The gap between average and maximum is almost entirely about predation rather than ageing.

When do chipmunks have babies?

Twice a year in most of their range. The first mating is in early spring, often February to April depending on latitude, producing a litter around April or May. A second mating in midsummer gives a litter in late summer. Gestation is about 31 days and litters are usually four or five young, with the second litter smaller on average. In colder parts of the range there is often only one litter a year.

How fast do baby chipmunks develop?

Slowly at first, then very quickly. Newborns are blind, hairless and about the size of a bumblebee, weighing around three grams. Fur appears in the second week, eyes open at about four to five weeks, and the young first emerge from the burrow at around six weeks. By eight weeks they are weaned and foraging, and within a few more weeks they disperse to dig burrows of their own. They are capable of breeding the following spring.

Do chipmunks hibernate?

Not in the strict sense that groundhogs do. Chipmunks enter a lighter state called torpor, dropping their body temperature and heart rate for several days at a time, then waking periodically to eat from the food cached in their burrow and to relieve themselves. That is why they hoard rather than fattening up — their winter strategy depends on a larder rather than on body fat. In mild spells they may emerge above ground even in midwinter.

How many chipmunks live in one burrow?

One. Chipmunks are solitary and territorial outside of mating and the period a mother is raising young, and each adult maintains its own burrow system, which can run to nine metres of tunnel with separate chambers for nesting, food storage and waste. What looks like a colony in a garden is a set of individual territories packed closely together, often with several burrow entrances per animal.

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