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Knowing Nature . . .

Western Toad Migration!

September 4, 2007
Jocie Ingram

Western Toadlets photo © Kayt Chambers

It starts around mid August, and it is a sight to behold. Every year, millions of baby Western Toads leave their birthplace in wetlands, and disperse overland. Unfortunately, some of the toad migration routes cross over the Inland Island Highway, resulting in high mortality. Two crossing sites have been very active this month on the section of highway between Courtenay and Campbell River. One of the sites is just north of Millar Creek, and the other, north of Pup Creek.

Local biologist Lynda Fyfe and a team of volunteers have been working around the clock to save the toads. At the Pup Creek site, plastic vapour barrier fences have been set up to prevent the toads from crossing the highway, and buckets have been sunk into the ground to catch more. There are so many toadlets that these buckets need constant emptying. This effort has resulted in saving thousands of toads. Toad tunnels put in at the Millar Creek site some years ago have been ineffective, since the toads do not like to enter the tunnels and will only do so if forced.

All frogs and toads are amphibians. Amphibian literally means “two lives” referring to the remarkable life cycle these animals have. Basically, they have two phases, a larval “water” phase and adult “land” phase. The cycle begins with the female laying eggs, protected by a coating of jelly, into the water. The eggs hatch into hatchlings, which grow into tadpoles. Eventually the tadpoles undergo “metamorphosis” or transformation into the adult stage. Legs slowly develop, followed by arms. The long fish tail is reabsorbed into the body. The new adult has lungs and breathes oxygen like you or I, and may spend quite a lot of time on land, but must return to water to breed.

Amphibians differ from other animals in that they don’t have fur, scales or feathers. The skin is naked, smooth, thin and moist. Water and oxygen can be absorbed directly through the skin, making amphibians particularly sensitive to pollution. Over the past decade frog and toad populations have rapidly declined. Water-borne pollutants, habitat loss, increased UV rays due a thinning ozone layer, and diseases carried by species introduced by humans are seriously effecting amphibians. Locally, protecting and appreciating wetlands and migration routes that amphibians depend on can have positive results.

Western Toad photo © Dave Ingram

The Western Toad has the charming Latin name “Bufo boreas” meaning “toad of the woods.” Toads differ from frogs in that they have “warts” on their skin. These are not warts at all, but glands which secret a toxic fluid when the toad is threatened by a predator. Adults are a motley mixture of cream, brown, gray, green and red with pale stripe down the center of the back. Western Toads grow to be quite large and can live up to eleven years. They tend to walk rather than hop and are able to dig themselves into the ground. Western Toads often urinate profusely if captured, so it is best to avoid handling them.

In addition to the Western Toad, two native species of frog are found in our area: the Pacific Treefrog and the Red-legged Frog. The Red-legged is slightly larger than the Treefrog, and has golden eyes and a brownish-red body with black spots. When flipped on its back, the undersides of the legs are red. Currently, Red-legged Frogs are rare or “blue listed” in BC.

The Pacific Treefrog, or Pacific Chorus Frog, is our smallest and most vocal frog.  They breed in water, but otherwise range to woodlands in search of insect meals. A special waxy skin coating enables them to retain moisture on these terrestrial expeditions. They vary in color from bright green, to coppery tan, and these chameleon-like changes are caused by fluctuations in temperature and humidity. A black stripe through the face easily identifies the Pacific Treefrog.

The Bullfrog is found on southern Vancouver Island, and has quite recently become established in the Comox Valley. Bullfrogs are giant frogs introduced from the Eastern US in the 1920’s and 30’s for the purpose of harvesting the meaty legs. Adults are green to brown with dark spots and a have a prominent eardrum. The upper lip is green, contrasting with a bright yellow chin (males) or white chin (females). Researchers from UVic are tracking the invasion of Bullfrogs in BC and the negative impact this species is having on our native frogs and fish.

Frogs and toads are sacred to First Nations, and have always captured the imagination of children and adults. These creatures, and their habitats deserve our care and respect.