Wood Frog - NAL

Wood frogs can range from 51-70 mm in length with females tending to be larger than males. Adult wood frogs are usually brown,tan, or rust-coloured, and usually have a dark eye mask. The under parts of wood frogs are pale with a yellow or green cast.

GEOGRAPHICAL SPREAD
The wood frog has a wide distribution across Northern America. It can be found in ephemeral wetlands from northern Georgia to northeastern Canada. These frogs are most commonly found in Alaska.

HIBERNATION
The wood frog, like other amphibians, are ectotherms meaning their regulation of body temperature is dependent on external sources, not controlled internally.

In winter, unlike other frogs or toads, wood frogs hibernate in deep cracks and crevices in logs or rocks or perhaps will dig down into a leaf litter. During this period, the wood frog would appear to look dead; in fact, its breathing, blood flow and heart have all stopped. However, the wood frog is far from dead, it is just partially frozen. Before, hibernation, urea is accumulated in tissues and liver glycogen is converted into glucose. Come winter, the wood frog will have a high level of glucose in its cells that act as an anti-freeze. This prevents the vital organs from freezing restricting the frozen areas to extra-cellular fluid where there will be no damage to the tissues. When spring draws near, its hibernaculum warms up above freezing causing the wood frog’s frozen body to thaw and it will come back to life.

BREEDING
In order to protect adult wood frogs and their offspring from predation via fish and other predators, these frogs primarily in ephemeral pools as opposed to permanent water bodies such as ponds or lakes. After hibernation, male, adult wood frogs migrate to their nearby pools where they attract a mate via their mating call. During the process of sexual reproduction, females will deposit their eggs attached to submerged substrate (commonly vegetation). Typically, females will deposit their eggs adjacent to another females eggs to creates large aggregations of masses. This helps to promote faster development for those eggs closer to the center, who will absorb the most heat, as opposed to those on the periphery along with greater protection against predators.

Breeding in early spring is a major advantage for the wood frog. It increases the offspring's chances of metamorphosing before the temporary pools dry up.