See a balls of leaves in trees in NJ? Probably not a bird’s nest

🔵 Is that a bird's nest up in NJ trees or something else?

🔵 You may be surprised to learn the answer

Now that the weather is getting nicer, it’s a great time to walk outside and look around at all that nature has to offer in New Jersey.

Speaking of nature, have you noticed these big balls of leaves nestled in branches high up in the trees?

Most people think they are bird nests. But guess what? They are not.

What is it?

They’re actually squirrel nests! The scientific name is a drey. By definition, dreys are usually built by squirrels using twigs, dry leaves, and grass, typically assembled high up in the trees.

You’ll notice they are built near the trunk or at the fork of two strong branches. This is to give it some stability

According to Bruce Crawford, manager of horticulture at the Morris County Park Commission, these dreys are often seen in trees during the winter months in New Jersey when the branches are still bare. It’s actually a common sight, he said.

“They (squirrels) craft their nests high in the trees to protect themselves and particularly their young from predators such as foxes, coyotes, etc.,” Crawford said.

Dreys are at least 20 feet off the ground for the best protection from predators.

 Constructing the drey

The outer, messy layer belies the organization of the inner layers, said Jenny Gaus, Superintendent of Environmental Education at the Morris County Park Commission. She explained that squirrels start making dreys when the leaves are still green, or at least not brittle, then they layer them making a spherical chamber within, often with two exits.

Twigs and sticks are not used alone, Gaus added. The beginnings of drey construction usually start with twigs with the green leaves still attached.

“If squirrels didn’t harvest the twigs at this stage, the leaves would just fall off, and these nests are as much for winter shelter as for raising young,” she said. The leaves are layered many layers thick for water-proofing and insulation, Gaus said.

While Eastern Grey squirrels typically build dreys in New Jersey, according to Crawford, not every grey squirrel will make one. Gaus said if they can find a tree hole of a suitable size and height off the ground, that is preferred. A tree hole is what these squirrels prefer to raise their first brood of young in the winter, she said. The second brood may be born in a drey in summer.

Flying squirrels, which exist in New Jersey can also make dreys, she said.

Unlike squirrel dreys, birds rarely use leaves at all in their nests, and they want a bowl-shaped cavity for the most part, with no roof, although materials used are unique to each bird, Gaus said.

Squirrel dreys are also much bigger than a bird’s nest. They can be anywhere from a foot to two feet wide.

So, the next time you’re outside, look up at the trees. You just may see a squirrel drey high up in the branches.

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