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Woodchucks fattening up for hibernation in late summer and fall

August to October

That woodchuck mowing the field edge is building the fat it will live on all winter: it is one of the few true hibernators in Massachusetts, and it eats nothing at all from fall until spring.

Why this time of year

Every meal before denning is winter fuel: woodchucks survive hibernation on fat reserves alone, losing 30 to 40 percent of their body weight underground, and the first of them begin denning as early as September, with most hibernating by late October.

How to notice it

  1. Scan field edges, big lawns, and highway margins; a feeding woodchuck sits up between mouthfuls to look around.
  2. In fall they shift toward mid-day feeding, so a lunchtime drive past open fields is prime time.
  3. Notice the shape: by now they look wide and low compared to spring.
  4. Sightings fade through October as one field's woodchuck after another goes underground.

Try this with kids: Does the woodchuck you found look skinny or already round like a football?

a true hibernator drops its body temperature and heart rate for months and lives on stored fat, not stored food

Sources

  • massaudubon.orgOne of the few true hibernators found in Massachusetts, woodchucks hibernate from October through March in winter dens; they are active during the day and inhabit fields, meadows, woodland clearings, and grassy areas along highways.
  • esf.eduWoodchucks rely on fat reserves rather than food caches to survive winter and lose 30-40 percent of their body weight while hibernating; they begin hibernating in September and early October and emerge gaunt and thin around March; they forage early morning and late afternoon in summer but mid-day in spring and autumn.
  • maine.govThe woodchuck is a true hibernator and depends on its fat reserve for survival; during the summer and fall it builds up this reserve and goes into hibernation in October, generally not emerging until March or April; it is diurnal, most active right after dawn and right before sunset.

In the guide for August, September, October

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