Pickerel Frog (Rana palustris)
Pictured above: Distinct dorsolateral folds with only two rows of spots or reticulations between them (left). Yellow coloration of belly and legs (right).
Description: Pickerel Frogs are generally brown or olive with distinct beige dorsolateral folds (pictured above). Most have black spots or reticulations along their back, like Leopard Frogs, however, unlike Leopard Frogs, these spots are rectangular and are found in two distinct rows between the dorsolateral folds. Their bellies are white with yellow patches along the groin and legs. Pickerel Frogs are medium sized frogs (2 to 4 inches snout to rump length). They are members of the family Ranidae, which includes other "true frogs", such as Leopard Frogs and Green Frogs.
Habitat/Ecology: Pickerel Frogs are said to prefer cold-water streams, however, I have most frequently found them in stagnant, warm-water wetlands. In the summer, they may venture into wet meadows located near ponds or wetlands. They spend most of their time hopping through damp grasses or along muddy banks in search of insects. Due to the fact that they are reported to have noxious skin secretions, I do not know the extent to which they are preyed upon by other animals.
Remarks: Males usually begin calling in May and June. Their call is a "snore" similar to the Leopard Frog, but is higher pitched and faster. Pickerel Frogs secrete a fairly toxic skin mucous that supposedly makes them distasteful to predators. These secretions are also toxic to other frogs. I have witnessed this first hand after accidentally placing a Leopard Frog in the same container with a Pickerel Frog overnight. After returning in the morning, the Leopard Frog had expired, while the Pickerel Frog was as alive as ever.
I have not witnessed or heard Pickerel Frogs in the La Crosse area, but I believe them to exist for I have found them in nearby Houston and Winona Counties (Minnesota). A fellow graduate student once found one in nearby Coon Creek, a trout stream located in the La Crosse area (lending credence to their reported affinity for cold, running water). If anyone has positively heard or found them there, let me know.
Pictured above: Compare the spots of a Leopard Frog (left) to those of a Pickerel Frog (right). Also, Leopard Frogs do not have the yellow coloration in the groin area that Pickerel Frogs have.