Squirrels build dreys, or nests, to keep warm and raise their young.
Hi. This is Scott Fitzpatrick from New Hampshire Audubon, bringing you Something Wild.
Recently a friend of mine asked me, "What the heck are those big leafy balls up in the trees?" Well, those are grey squirrel nests, which are also called dreys. And some of them may be filled with squirrels.
Grey squirrels generally prefer to build their nests in tree cavities, but when those are scarce or already occupied, they'll build leaf nests near the tops of large trees. A platform of twigs forms the floor of the drey, which is covered by an outer shell of leaves and twigs. Moss, grass, shredded bark and sometimes even cloth or feathers line the inner chamber. Finished nests are one to two feet in diameter.
In the fall, squirrels build winter dreys, which are quite sturdy. Winter dreys provide shelter from cold weather, and a place to rear young.
Squirrels do not hibernate, but they will spend several days in the nest during particularly cold or stormy weather. Several female squirrels may den together for warmth, and a cold male might even try to get himself invited in. But when the temperatures rise, all guests are kicked out!
Grey squirrels mate in late winter. You might have noticed courtship chases in late January or February, and the pregnant female rests in the drey. Up to three young are born around forty days later. Baby squirrels are born naked, blind and deaf. They develop more slowly than other rodents and are not able to leave the nest for eight weeks. During that time the nest provides them with a safe and cozy home.
In summer, less sturdy dreys are built by female squirrels to house a second batch of babies until they are ready to leave the nest.
For Something Wild, I'm Scott Fitzpatrick.
Something Wild is a joint production of New Hampshire Audubon, NHPR and the Society for the Protection of New Hampshire Forests.
If you have a natural history question, e-mail us at somethingwild@nhpr.org.
