KINGDOM ANIMALIA: VERTEBRATES

AMPHIBIANS

The term amphibian is based on the Greek words amphi (double) and bios (life) because amphibians spend their lives in water and on land. They are cold-blooded. Amphibians have soft, moist skin and no scales. Different life stages may breathe through skin, gills, or lungs. The eggs of some species of amphibians are covered with a gel. In Nova Scotia, amphibians include one type of newt, four types of salamanders, one type of toad, and seven types of frogs.

EASTERN REDBACK SALAMANDER (Plethodon cinereus)

Nesting Season May - June No. Eggs 4-17 Egg Pattern Singly, loose group on damp log or rock

The redback salamander is the most abundant amphibian in Nova Scotia. Unlike the three other salamanders and one newt species found in the province, the redback is fully terrestrial. It is associated with moist areas in or under leaf and needle litter, stumps, logs, and rocks from forest floors to suburban gardens.

Three distinct colour variations are known. The redback phase (reddish stripped back and dark sides) is the most common and is usually found in hardwoods; the leadback phase (gray to brown) is more frequent in softwoods and mixed woods, especially coastal areas; and the uncommon all-red phase is associated with highland deciduous areas. Adults range in length from 7 cm to 10 cm.

Juveniles and adults avoid freezing by staying underground from October through April. Mating usually occurs in late fall, and the females retain sperm until fertilizing and laying eggs the next summer. Four to 17 eggs are laid in June or July in moist, well-rotted logs and stumps. Females guard the eggs until the larvae hatch in August or September.

Redback salamanders feed on invertebrates such as ants, beetles, flies, wasps, spiders, mites, snails, and worms found in the soil and litter. They are preyed upon by jays, thrushes, grouse, skunks, raccoons, and foxes. Their primary predators are snakes. An interesting adaptation of salamanders is their ability to regrow limbs and tails that may be cut off by accidents or predators.

SPRING PEEPER (Hyla crucifer)

Nesting Season Early April - Early June No. Eggs 400-1,600 Egg Pattern Singly, in bottom debris

Spring peepers are extremely abundant in all woodlands near ponds, marshes, and swamps throughout Nova Scotia. Adult males are 2 cm to 3 cm in length, while females average 2.7 cm to 3.7 cm. The species name, crucifer, refers to the distinguishing cross, or X-patters, on the back. Skin colour varies between shades of brown or gray on the back and sides, to white or yellow underneath. Spring peepers are typical tree frogs with long legs, slim waists, and adhesive discs on each toe. They climb vegetation and can darken or lighten body colour to match the colour of their environment.

Spring peepers hibernate underground from October to late March or April. I may be the smallest frog in the province, but during April to June breeding period its deafening evening chorus makes it the most obvious frog. Males attract females with a high-pitched "peep-peep-peep" 15 to 25 times per minute.

Females come to breeding sites long enough to mate and lay several hundred eggs underwater, Eggs hatch in six days with warm weather. Tadpoles develop over two to three months before transforming into frogs and becoming terrestrial. Tadpoles feed on soft-bodied invertebrates. Up to half of the diet is spiders, along with midges, mites, ants, sowbugs, nematode worms, moth larvae, and other invertebrates. Fish, frogs, and newts, and carnivorous insects prey on the tadpoles. Common predators of the adults include snakes, birds, and other frogs, such as the bullfrog and green frog.

BULLFROG (Rana catesbeiana)

Nesting Season Mid June - July No. Eggs 12,000-22,000 Egg Pattern filmlike mass on water surface

In Nova Scotia, there are six species of typical frogs (bullfrog, green frog, mink frog, northern leopard frog, pickerel frog, and wood frog), one tree frog, and one toad species. Frogs have moist, smooth skin and they leap. Toads, including our eastern American toad (Bufo americanus), have dry, rough skin and they hop.

Our largest frog is the bullfrog at 9 cm to 15 cm. Breeding males are generally green on the head, yellowish green on the body, and yellowish green with brown spots on the legs. Adult females tend to be darker with brown spots on the back and bands on the legs. Their throats are yellow and the underparts are yellowish white. Bullfrogs are common throughout central and western parts of the province, common in scattered locations of the eastern mainland, and unrecorded in Cape Breton. The bullfrog is limited to aquatic habitat such as lake coves, ponds, slow-moving rivers, and boggy stretches of streams. Their primary habitat requirement is a permanent body of water with lots of vegetation where adults and tadpoles can hide.

Other frogs have often completed courtship and egg-laying by the time adult bullfrogs emerge from hibernating on silty bottoms. Overwintering tadpoles emerge first in mid-April, then subadults, and then adults in mid to late May. Males begin their nightly booming "jug-o'-rum" courtship calls in mid-June. Breeding continues through July. Females lay 12,000 to 22,000 eggs as a film on the water surface. Eggs hatch in 4 to 20 days, depending on water temperature. Tadpoles take two more years to develop into young bullfrogs, showing hind legs after two winters.

Bullfrog tadpoles are mostly vegetarian, using their teeth to snip the tips of aquatic plants. Adult bullfrogs are aggressive predators, feeding on a variety of animal life. In Nova Scotia, their prey has included spiders, mites, minnows, 32 types of insects, and 5 species of amphibians. They frequently eat their own tadpoles and young, as well as those of green frogs. Bullfrog tadpoles are eaten by some diving beetles and dragonfly nymphs. Adults and young are both preyed upon by herons, raccoons, minks, and snakes. The leg meat of bullfrogs is considered a delicacy by some humans.