The Nightlife of the Natural World (part 2 of 2)

by Kevin Strauss

We often think of nighttime as the time for romance. Humans visit bars and nightclubs to meet that special someone and frogs sit in the swamp and sing. For weeks now our northwoods nights are full of male frogs and toads singing to attract a mate.

Here in mid-June, we hear the high-pitched sleigh-bell call of the spring peeper, the snoring call of the northern leopard frog and the high-pitched trill of the American toad. One reason frogs and toads are more active at dusk and nighttime could be related to their skin. Frogs and toads don't every drink water the way that we do. Instead they absorb moisture through their permeable abdominal (belly) skin. They absorb the water by sitting in water or on damp grass. But since they absorb water through their abdominal skin, they can also lose water through it the same way while sitting on dry ground or in the sunshine. By waiting until evening to emerge from the water and grass, frogs and toads conserve precious water.

Night can also be a safer time for frogs and toads. Many of the their predators like great blue herons, American bitterns and northern water snakes are less active or sleeping at night, making it easier for frogs and toads to sign without ending up in some predator's stomach. Frogs and toads may also be active in the evening for the same reason that bats are: to eat moths, mosquitoes and other night-time bugs.

Spring Peepers (Pseudacris crucifer)

Spring peepers are in the middle of their breeding season right about now. They started singing in April and go until August, filling our nights with the sound peeping sound of sleighbells. This is one frog you often hear, but never see. That's because these frogs are only about one inch long! And unlike larger frogs and toads, treefrogs can use the pads on their toes to help them climb onto shrubs and trees, safe from ground predators. They have tan or brown skin and an X on their back (hence the species name crucifer or cross). After breeding, these secretive treefrogs disappear into the forest until next spring.

Northern Leopard Frog (Rana pipens)

The northern leopard frog is the only frog in Minnesota to live in all of our 87 counties. This frog can survive in a number of habitats, but they are most often found in meadows and fields new lakes and swamps. This frog gets its name from the leopard-like brown spots on its green skin. Leopard frogs measure about three inches in length and in the south, they used to be harvested for frog legs dinners. These days, with the national decline of frog species, they are no longer common enough for harvesting.

American Toad (Bufo americanus)

Most people are familiar with our common toad. This brown, bumpy toad is almost as common as the northern leopard frog. Some of the bumps on a toad carry a bad-tasting poison, meant to deter predators like snakes and dogs. If you do pick up a toad, always wash your hands afterward, since some of this irritating poison may get on your hands. Also, when frightened, toads tend to urinate. While toad tadpoles live in ponds and swamps, the adults live in forests, fields and backyards, returning to water only to attract a mate and breed. Then like all toads and frogs, the female lays eggs in the water, where they hatch into tadpoles and begin the lifecycle all over again.

The Ely Timberjay