Comox Valley Naturalists Society
On the Wild Side . . .
It’s a spring ritual to hear the frogs singing at the neighbourhood pond. Listening to that din on a bright starry night is strangely enchanting. The choristers, all male, are out to impress the females with their fine voices. There is even a “choir master” a frog that signals the beginning and end of each night’s singing (apparently scientific studies have proven this).
It is hard to believe that these gusty voices arise from our smallest frog, the Pacific Treefrog, otherwise known as the Pacific Chorus Frog. Treefrogs 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.
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. Dishearteningly, the decline is largely caused by humans. 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 that amphibians depend on can have positive results.
The Comox Valley is home to two species of frog and one species of toad. In addition to the Pacific Treefrog, the Red-legged Frog also resides here. 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. Red-legged Frogs sing underwater, so humans don’t hear them. Currently, Red-legged Frogs are rare or “blue listed” in BC.
The Bullfrog is found from Victoria to Parksville, and a few sightings have been reported from our area. Bullfrogs are giant frogs introduced from the Eastern US in the 1920’s and 30’s for the purpose of harvesting the meaty legs. Being up to 20cm long, Bullfrogs eat anything they can. They like warm, weedy ponds and thrive in coastal BC. 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). The male’s song is a low-pitched two-note drone. 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.
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 are quite large and are widely distributed through BC. 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.
Frogs and toads are sacred to First Nations, and have always captured the imagination of children and adults. These creatures, and their wetland habitats deserve our care and respect. Let the chorus sing on!
Click on a link below to view the CVNS newspaper column.