Amphibians - Frogs, Toads and Salamanders

Frog Watch

Cold-blooded Creatures
Frogs, toads, salamanders and newts are all amphibians. These animals rely on outside temperatures to keep their bodies warm enough to survive. This is not always easy in the North! The word amphibian means "double-life", in reference to living both in water and on land. Most amphibians lay their eggs, protected only by jelly, in the water. The young go through a larval stage, breathing through gills and swimming with fins, before transforming into adults. Although most species have lungs, they also breathe through their moist skin and the lining of their mouths. Amphibians do not drink water - instead they absorb it through their mucous-moistened skin.

Concern for Amphibians
Amphibians are a part of our local biodiversity, the amazing variety of life around us. Conserving biodiversity is essential to the health of the planet and the welfare of humankind. Amphibians also have a special role to play in keeping the environment healthy. Perhaps because they live "on the edge" between water and land, amphibians are very sensitive to pollution and other environmental changes. World-wide, many species are declining in numbers or have recently become extinct. By tracking the health of amphibian populations, we can detect larger environmental problems.

Ways of Life
The amphibians of the Yukon and northern BC hibernate in winter. With the warmth of spring they emerge and migrate to traditional breeding ponds. The males of most species call to attract mates in a lively chorus, while voiceless salamanders and toads search for their mates by smell. Mating and egg laying take place in the water, where eggs and young are left to fend for themselves.

The eggs develop rapidly and hatch into larvae. Frog and toad larvae, called tadpoles, are good swimmers and eat mostly plants. Salamander larvae, which eat insects, develop legs quickly so that they can walk on the bottom of the pond. The tadpoles of some species forage in schools and use chemicals to communicate and warn of danger when wounded. Over several weeks the larvae transform into air-breathing, land-dwelling animals.

Adult frogs, toads and newts are active in the daylight hours in the North, and feed on insects and other small creatures. Salamanders are nocturnal, hiding under logs and leaf litter. With the onset of freezing temperatures in late summer, amphibians retreat to their hibernating sites.

Life in the North
Amphibians are cold-blooded and must obtain their warmth from the environment. Their colonisation of the North has been limited by extremely cold winters, cool short summers, scarcity of hibernation sites and insufficient snow cover.

In winter, northern amphibians survive by hibernating underground, under ponds or under leaf litter beneath a thick blanket of insulating snow. While most amphibians freeze to death if cooled below -1°C or -2°C for more than a brief period, a few northern species actually have antifreeze in their cells to allow them to survive to a temperature of -5°C to -7°C. Wood Frogs and Boreal Chorus Frogs, for example, use glucose in their cells as antifreeze that prevents the cells from bursting in these freezing temperatures. In effect, these frogs can be 'frozen solid' during hibernation and still emerge safe and sound in spring.

Northern amphibians take full advantage of the warmth of the spring and summer sun. Eggs are large and dark to help absorb heat. They are submerged in warmer shallow water safely below the surface which might freeze. Tadpoles love to bask in the sun in the shallows while adult frogs and toads bask on land or in shallow water in the heat of the day. Some amphibians which are nocturnal in warmer climates prefer the warmest and brightest part of the day in the North.

Wood Frog (Rana sylvatica)
Wood Frogs are the most common and widespread amphibian in our area. They are found farther North than any other amphibian in North America - and occur at least as far north as the Yukon's Old Crow Flats. They inhabit forests, meadows, muskegs, and even tundra.

The colour of the Wood Frog is highly variable, ranging from brown, tan, or grey to pinkish, with a dark eye mask, white jaw stripe and creamy white underside. There may be a light stripe running down the middle of the back. Adults range up to 50 mm in length. Wood Frogs congregate for breeding in clear, shallow ponds in late April and through June. Listen for their choruses of duck-like quacks.

Spotted Frog (Rana pretiosa)
Records of the Spotted Frog are sporadic in northern BC and southeastern Alaska; the species appears to occur only in the southwest Yukon. This species was first discovered in the Yukon in 1994 in two ponds on the west shore of Bennett Lake.

The Spotted Frog is more aquatic than the Wood Frog and prefers permanent ponds up to treeline. It may forage on land during the day, but generally remains near the shore or even in the water, where it sometimes feeds underwater. It loves to bask in the sun. If frightened it will swim to the bottom of the pond and wait in the mud.

The Spotted Frog is sturdy and much larger than the Wood Frog, reaching 100 mm in length. Small bumps and dark irregular spots with light centres are scattered on its olive, tan, light brown or dark brown skin. It has a light-coloured jaw stripe. The underside is creamy, covered with salmon or red near the hind limbs, and mottled with grey elsewhere. Northern Spotted Frogs have shorter legs than their southern counterparts, possibly to conserve heat and moisture.

Boreal Toad (Bufo boreas)
The Boreal Toad is found throughout most of northern BC, and in the Yukon only in the Liard Basin. It prefers damp conditions but can be found in meadows or forests quite far from water. It can be found in brackish water on the coast. Nocturnal further south, the Boreal Toad is active during daylight hours in the North.

The Boreal Toad is large, up to 125 mm in length, and chunky, with short legs, numerous warts and dominant parotoid glands at the back of the head. The colour of the back varies between green, brown and grey, and is covered with reddish warts surrounded by dark blotches. There is a light stripe down the middle of the back, and the belly is white with dark mottling. A grey 'pelvic patch' in the groin area is capable of absorbing water from the ground. Few predators other than snakes will eat adult toads because of foul-tasting poison they exude from their parotoid glands and warts. The poison irritates the skin of some people.

Boreal Chorus Frog (Pseudacris triseriata)
Common east of the continental divide, the Boreal Chorus Frog is found in the Liard and Peace River basins in BC and reaches the Yukon along the La Biche River. It inhabits damp grassy or wooded areas, but is seldom seen since it spends most of the summer underground. Boreal Chorus Frogs hibernate underground and, like the Wood Frog, can tolerate some freezing.

The Boreal Chorus Frog is small with a long body and short legs. It is grey, brown or green, with three irregular stripes down the back and dark stripes on the sides, extending from the nose to the groin. The belly is white, yellow or olive, with a few dark markings.

Long-toed Salamander (Ambystoma macrodactylum)
The Long-toed Salamander is believed to be absent from much of northern BC, but has been found in the Stikine and Taku watersheds in northwestern BC and southeastern Alaska. It prefers damp areas at forest margins, and enters water only to breed. The Long-toed Salamander hides under rocks, rotten logs or leaf litter and emerges during rainy periods.

Long-toed Salamanders are dark grey, brown or black. They have a prominent green or yellow stripe running down their back and white flecks on their sides. They are grey underneath, and are up to 120 mm in length.

Other Amphibians to Watch For
These species have not yet been recorded in the territory but may occur.

Rough-skinned Newt (Taricha granulosa)
The Rough-skinned Newt has a rough, dark brown back, and a bright orange or yellow belly. It breeds in spring in shallow ponds, bogs and swamps. Rough-skinned Newts are found near permanent ponds, including brackish water, or in open mixed coastal forests with lots of leaf litter and deadfall. Adults may also live in water.

Northwestern Salamander (Ambystoma gracile)
These large chunky salamanders are usually deep brown, grey or black on the back and lighter brown on the belly. They may have dark or yellow specks on their back. Northwestern Salamanders inhabit coastal forests at least as far north as extreme southeastern Alaska. Look for them under rocks, boards and logs near ponds.

Tailed Frog (Ascaphus truei)
The Tailed Frog is usually olive, brown or grey, but may be pinkish or even black. Its colour matches the rocks in its habitat. The male has a 'tail', or extended cloaca, used for breeding. Tailed Frogs forage for insects on land and in clear, cold coastal mountain streams.

Red-sided Garter Snake (Thamnophis sirtalis)
The Red-sided Garter Snake is a reptile, not an amphibian. Although no reptiles have been found in our region, this is the most likely species to occur here. The Red-sided Garter Snake is a large, slender reptile up to 130 cm long. The back is dark olive to black, with three greenish, yellow, orange or blue stripes, and red or orange bars on the sides. Like amphibians, snakes are cold blooded, but have hard dry scales covering their bodies. The Red-sided Garter Snake is found near lakes and streams or near the sea and will take to the water when disturbed.

Taking Amphibians Home
Do not keep wild amphibians as pets. Release them where they were captured as soon as they have been identified and studied. Do not move them to foreign ponds. Handle them as little as possible. Insect repellent on your hands can harm amphibians, which breathe through their skin.

What Can You Do?
To help increase our knowledge of amphibians in the Yukon and northern BC, please check out Frog Watch, a national monitoring program for amphibian populations.

Contacts:
For further information or copies of the complete Frogs, Toads and Salamanders brochure, please contact the Wildlife Viewing Program, Department of Environment at (867) 668-8291.

Frog Watch