Calling All Frog Watchers!
Early spring is the time for frogs to wake up from hibernation and start to call for a mate. Wood frogs (Lithobates sylvaticus), spring peepers (Pseudacris crucifer) and northern leopard (Lithobates pipiens) frogs are the first to appear in spring. Check out our website to start identifying these frogs and more by their sound: Ontario Frogs
Wood frogs are brown, tan, or rust colored, and usually have a dark triangle shaped eye mask. Wood frogs hibernate close to the surface in soil or leaf litter because they can tolerate up to 65% freezing of their blood and other tissues. How do they do that? Well as long as the frog’s cells don’t burst, the wood frog can thaw out unharmed. Their cells are protected by both the accumulation of urea and glucose which act as “cryoprotectants” to limit the formation of ice crystals and reduces osmotic shrinkage of cells. The wood frog is so good at freezing/thawing that is became the only North American amphibian found north of the Arctic Circle
Wood frogs are the first frog to appear in the spring and can often be heard calling when there is still ice on the pond. Their call sounds like a rolling quack often mistaken for a duck. They breed primarily in ephemeral, non permanent, pools and hibernate next to them for easy access in the spring. Individual wood frogs can travel hundreds of meters between their breeding pools. Towards the later part of the summer, they will then travel up into their upland forest habitats. This makes conservation of this species tricky as it requires large landscapes with multiple habitats.
Spring peepers are tan or brown in color with a dark cross or X on their back. This cross pattern adds to their Latin name crucifer or cross-bearer. These frogs are about the size of your thumb, but don’t be fooled by these little guys as they can be quite loud! The males are the only ones that call using a high-pitched “peep” that can be deafening in spring. This species has large toe pads for climbing, but is most often found in the leaf litter of the forest floor. Like the wood frog, spring peepers hibernated and breed in and near ephemeral pools.
The northern leopard frog is a fairly large species of frog, reaching about 5-11 cm in length. It varies from green to brown, with large, dark, circular spots on its back, sides, and legs. Each spot is bordered by a lighter ring. Leopard frogs have white/pink folds that run from their eyes parallel to each other down their back. Northern leopard frogs have a wide range of habitats and like to travel between them. They are found in permanent ponds, swamps, marshes, and slow-moving streams, but also like to visit moist forest, wet fields, and urban ditches. They are early callers and are adapted to survive in the cold. Males make a short chuckling sound similar to if you were to rub your hands on a wet balloon.
Before the 1970s, the northern leopard frog was spotted everywhere but habitat loss and fragmentation, environmental contaminants, introduced fish, drought, disease and use of these frogs in the food and bait fishing industry have decline their populations. Even with remediation and new laws, these populations still haven’t bounced back in much area across Ontario.