2014-03-21 / Front Page

Amphibians Herald Arrival of Spring

By Jack Kelly

The northern leopard frog is named for the black spots across its green back. The northern leopard frog is named for the black spots across its green back. Many significant signs in nature herald the coming of spring. One of the more unique passages into this long-awaited season is the awakening of the region’s amphibian populations from their winter hibernation. Peeping, croaking and other mating calls mark their arrival.

Frogs hibernate by burying themselves in the muddy bottoms of ponds because amphibians cannot regulate their body temperatures like mammals and birds. They feed heavily in the warm months to produce a layer of fat that will sustain them during hibernation. As winter approaches, frogs suppress their metabolism and enter a state of torpor. During this time they are able to collect oxygen, or “breathe,” through their specialized skin.

Toads will dig holes and burrow below the frost line, where they will spend the cold months. Salamanders and newts will often use established holes or vacant burrows to create their hibernation nests, usually lined with vegetation to hold in warmth. Amphibians begin to wake from their winter respite around the time of the vernal equinox.

Bullfrog. Bullfrog. According to the Rhode Island Department of Environmental Management and the University of Rhode Island, there are 18 species of amphibians across the state. Aquidneck Island, as well as the other islands of Narragansett Bay, hosts a more limited selection of species than the mainland. However, there is enough variety to keep any wildlife enthusiast searching meadows, wetlands, and the boundaries of ponds, streams and brooks for an entire season.

The state’s frog and toad populations include the northern leopard frog, bullfrog, wood frog, northern spring peeper, gray tree frog, green frog, pickerel frog, and the eastern American toad.

One of the most interesting species, the northern leopard frog, is rare in Rhode Island, but there are known, scattered population sites on Aquidneck Island which have been charted by URI biologists. Once one of the most abundant frogs in the United States and Canada, the food industry (frogs’ legs) and the science community (dissection samples for biology classes) have taken a toll. Pollution, deforestation, and rising water acidity levels since the mid-1970s have also played a role.

The northern leopard frog is named for the black spots across its green back. It measures threefive inches in length from nose to rump, with the female being larger than the male. Nicknamed the meadow frog, this species lives near freshwater ponds and wetlands. It hibernates in the substrate of permanent ponds and in the spring migrates to breeding sites. It will eat anything it can fit into its mouth, including beetles, ants, flies, worms, smaller frogs (including its own species), small birds and garter snakes. According to the most recent census of this population, this breed is limited to Aquidneck Island, Conanicut Island, and a few points on the eastern side of Narragansett Bay.

Another local inhabitant is the green frog, a common and widespread resident of ponds and lakes across the mainland and on most bay islands. Nicknamed the screaming frog, it will typically leap into water while emitting a loud cry to avoid predators. The green frog also winters deep in the muck of ponds and emerges in early spring prepared to breed.

The Norman Bird Sanctuary is hosting “Eyes on Amphibians,” on Friday, March 28, from 5:30-7 p.m. The evening of nature exploration will begin with a brief natural history of local amphibian populations, followed by a guided hike to Red Maple Pond to listen for frog calls and to search for egg masses. The programming is suitable for ages 7 and up and does require registration. The cost of admission is $6 for members and $8 for nonmembers. For more information, visit normanbirdsanctuary.org or call 401-847-2577.

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