Red Mountain’s Vernal Pools

Biologists are having lots of fun exploring Red Mountain Park. Among their discoveries are vernal (referring to “spring”) pools, small wetlands in the landscape where low places trap water on its way downhill. The pools can be natural features or a happy accident from the way humans have altered the landscape. They usually form in late winter and early spring, the time of year when rainfall is highest in the region. Regardless, these wetlands attract many amphibians, not just because they provide a place to breed or hunt, but because the wetlands dry out for part of the year. Does this sound backwards? Here’s how it works…

Many fish are voracious predators of amphibians. They’ll eat their jelly-like eggs, fully grown adults, and every stage in between. But native southeastern fish need water to survive. And when a wetland goes dry, fish die. Thus, safe from the hungry mouths of fish, vernal pools become important breeding habitats for many amphibians .

The vernal pools at Red Mountain Park are used for breeding by Southern Leopard Frogs and Cope’s Gray Tree Frog. These frogs can gather in the pools by the hundreds. When they begin chorusing – males singing all at once – the volume of noise can seem deafening. Other amphibians in the park that likely use the pools include the American Bullfrog and Fowler’s Toad.

Vernal pools in areas where there have been fewer disturbances – such as Oak Mountain State Park – have a greater diversity of pool-breeding amphibians, including salamanders. With time, some of these species may return to Red Mountain Park.

Of course, just because there are no fish doesn’t mean the vernal pools are a breeding paradise for amphibians. Other predators visit the pools in hopes of picking off unsuspecting adults or munching on egg masses. The Red-shouldered Hawk, a species common in the region, is an accomplished frog hunter. Common Snapping Turtles have been found in Red Mountain’s vernal pools. And a variety of snakes are clever enough to patrol the margins of the pool in hopes of capturing unsuspecting frogs.

-R. Scot Duncan