Wood frogs gather in shallow ponds during a short period in February or even late January to mate and lay their eggs. This year is one of the earliest appearances that I’ve observed, with frogs in our pond on the 25th of January, and eggs by the 26th. The frogs are usually evident only for a week or so, but may gather a second or even third time if the warm rains continue.
The males call to females, advertising both their pond and their availability. When the females arrive, most of the males in the pond congregate around them, pushing and jostling each other to be the first male to reach each female. Because the eggs are fertilized as they are being laid, the cluster of males around each female ensures that all the eggs are fertilized, and often by different males. The males’ calls sound just like the quacking of ducks, and they call whenever it’s warm enough for them to be active, which is usually late afternoon or early evening. If you hear, but don’t see, ducks on a local pond, look instead for frogs.
Eggs are laid in fish-free ponds or even temporary puddles. Each individual egg is like a tiny grape with a single black seed in the center, which is the developing embryo, but all the eggs laid by one female are stuck together. This egg mass can be the size of a large grapefruit and is often attached to a piece of aquatic vegetation or a submerged stick. The frogs choose a shallow area that receives some warmth from the sun, allowing the eggs to develop more rapidly. They are also attracted to other egg masses and tend to lay in clusters. If, however, a later bout of cold temperatures causes the pond to ice over, the uppermost eggs freeze and are killed, but the eggs that remain deeper in the water do not freeze and usually survive.

The adult frogs are a different story. They can survive being completely frozen as long as their temperature does not drop below about 25 degrees Fahrenheit. As they chill, they move sugar from their liver into their blood and tissues, and this acts as antifreeze. During the cold winter months, the adult frogs hibernate by burrowing into the soil. Because of this ability to withstand cold temperatures, wood frogs are widely distributed in the northern states and all along the Appalachian Mountains.
The tadpoles develop rapidly when the water warms up, and the newly metamorphosed wood frogs often leave their natal pond shortly after other frogs begin to lay their eggs. Their early breeding period may be a way to minimize competition from other species of frog that utilize the ponds later in the season or to avoid the warmer-season predators such as snakes, turtles, and other frogs.

Wood frogs are easy to identify by sight as well as by sound. They are tan-colored with black masks across their eyes. Unlike many of our other frogs, they travel far from water when they are not breeding in the pond. In the forest, I have most often encountered them as tiny froglets that have recently metamorphosed from tadpoles.

The scientific name of wood frogs is Rana sylvatica, which is just a beautiful way of saying “wood frog”! Rana is the common group of large frogs, and sylvan refers to wooded, or forested.

So keep an eye on any nearby shallow pond this February and listen for the frogs who know that spring is on the way. Then rush back in and put another log on the fire!