Grey Tree Frog: An Ogemaw County Year

Every spring, when the angle of the sun shifts just enough to send a warm beam through the east-facing window onto my Boston fern, my Boston fern starts singing. Well, not the fern itself, of course—but the little grey tree frog that’s made its home among the fronds wakes up and begins calling. His voice, a short, melodic trill, fills the room with the sound of early spring, even while patches of snow linger outside.

I first noticed him late last summer, a small, greenish speck nestled against the damp soil of the fern’s pot. At the time, I had brought the plant inside to protect it from an early frost, not realizing it carried a quiet stowaway. Over the winter, he stayed silent, blending so well with the lichen-like greens and grays of the fern that I sometimes wondered if he’d slipped away. But now, as the days lengthen, he makes his presence known, his call both a surprise and a promise of the season to come.

Grey tree frogs (Hyla versicolor) are a marvel of adaptation. Their skin can shift from gray to green, allowing them to blend seamlessly with tree bark or leaves. In Michigan, where winters can be harsh, these frogs survive by producing glycerol in their tissues—a sort of natural antifreeze. They can endure being partially frozen, their hearts slowing to near stillness until warmth returns.

The call I hear is a mating call, meant to attract a female. In the wild, this would be the time when males gather around ponds or vernal pools, singing from hidden perches. Females choose their mates based on the quality of the call, and once paired, they lay eggs in shallow water. These eggs hatch within days, and tiny, gilled tadpoles emerge. Throughout the summer, the tadpoles transform, absorbing their tails and developing the sticky toe pads that allow adult frogs to cling to almost any surface. By late summer, a new generation of tree frogs is ready to head into the canopy.

One lesser-known fact about grey tree frogs is that they produce a mild toxin through their skin. This toxin isn’t dangerous to humans but can cause irritation if you handle them and then touch your eyes or mouth. It’s a small reminder that these little creatures are wild, even when they take up residence in a houseplant.

I’m glad to have this unexpected guest, his voice filling the quiet corners of the house with a sound that feels like hope. But I know his place isn’t here. As soon as the nights are just a bit warmer and the risk of frost has truly passed, I’ll take the fern outside, setting it in a shaded corner of the garden. I’ll let him find his way to a proper pond, where he can add his voice to the spring chorus and perhaps help start a new generation of tiny trillers. Until then, I’ll enjoy his song—a reminder that spring always comes, even if it sometimes arrives on four tiny, sticky-toed feet.