The next time you have the opportunity to drive south from Campbell River on the Inland Island Highway, take note that just past the Hamm Road connector, about 15 minutes south of Campbell River, the double fences paralleling the roadside on both sides of the highway. These large elk and deer fences have short, tight mesh mini fences running along the base that are about 25 centimeters high and continue for quite a few kilometers south.
Being of a curious mind, I have always wondered why these fences were different on this stretch of highway. After questioning a couple of authorities in regards to these unusual fences it was concluded that they were frog fences and if you were to pay particular attention to the configuration of the smaller fences you will notice that at regular intervals these fences wrap around what looks like culverts that go underneath the highway, “froggy tunnels”.
So why would we need frog fences on the inland Island Highway? I was fortunate enough last summer to witness first hand the annual migration of the frogs and the spectacle was really something; I could not remove the smile off my face for quite a few days afterwards and I still smile when I think of it. Our group missed the adult migration but we did observe the baby frogs returning from the swamps to make their way back into the tree line. WOW.
Every spring the adult tree frogs that live in the forest lands from the base of Mt. Washington all along the east side of the most easterly range of mountains, migrate up to 30 kilometers, to the swamps and peat bogs of the MacAulay Road and York Road highlands to lay their eggs. Millions of these 6 to 10 centimeter long green and brown frogs make up the exodus every season. The Inland Island Highway transects the migration path, hence the fences were erected to protect the frogs from being run over and to prevent humans from car accidents due to the slick and slimy hazard thousands of squished frogs would create on the highway.
The implicit volume of frogs migrating is staggering to the mind, with the estimates in the millions. Our observation party included; two dogs, 7 kids and 6 adults, three cameras, a bunch of pairs of gum boots, a few catch buckets and a picnic blanket. We selected a spot that we might be able to just sit and relax with the kids, but it was difficult to lay the blanket down in the fear that we were sitting on the frogs. There were so many of them we had to take great care where we placed our feet, the ground was literally alive with movement.
We spent the better part of four hours with the kids that day, catching and releasing these babies and just watching them make their way through the grass into the forest, taking some really bad pictures (the frogs just don’t stay still) and generally enjoying this most unusual exhibition in Mother Nature’s Amphitheatre. The kids did take a small number of the baby’s home to study but we made a point of releasing them in local forests a few days later. This activity is highly recommended, particularly for the little ones, mid July is the best time to observe the babies with about a two week window.
It is also a great opportunity to learn and teach a little about the natural wonders that make up our island, as in all our excursions we insert an educational component to the day. In this case we brought along written descriptions for identifying the frogs, we measured them to determine age (that turned out to be very difficult) we drew the migration paths on maps and made a point of discussing habitat and protection issues with the kids. A great day was had by all. I think the Adults in the group actually had more fun than the kids. Vancouver Island’s Most Prominent Frog Species
The general form is delicate; length about 3 to 5 centimeters, with a flat head and prominent eyes, ear membranes are about one-half diameter of the eyes, parotaoid gland is absent. A fold of skin exists across the breast between the attachment of front legs, fore and hind legs are of moderate length; fingers and toes end in round disks, toes of the hind legs are webbed for half their length, the skin moist and covered with minute tubercles.
The coloration is highly variable; the ground color can be brown, bronze, green or grey. A dark band is underlined by a lighter stripe usually from the nostril backward through the eye and ear to shoulder. Dark, elongated blotches usually present on the back and limbs and a Y-shaped blotch is often found on top of the head, the two arms extend over the eyes, with the stem pointing backward. The eye has a bronze iridescence. Under parts are whitish and occasionally salmon colored. Some specimens lack the darker pattern except the dark bank through the eye; all are capable of changing color to some extent.
The Pacific Tree Frog is readily recognized by the conspicuous disks on the toes and by the dark bands on the cheeks.
In British Columbia it is found chiefly in the south-central and south-western part of the Province, including Vancouver Island and adjacent islands.
Habitat and Habits:
One of our best known amphibians, it congregates in large numbers each spring in almost every pond and swamp and begins a chorus of loud croaking which may be heard a great distance. Only the males croak. In spite of their small size the sound is extremely loud, being amplified by a resonating sac which, when fully expanded, swells the throat to a size three times as large as the head. The individual call appears to consist of two notes, sounding much like the phrase “wreck it”. The croak is repeated at intervals of two or three seconds and may continue through the night and part of the day during the spawning season.
The eggs are laid in February, March, and April on the islands. They usually number twenty to fifty per adult and are enclosed in small clusters of jelly attached to grass stems or other similar supports, often below the waterline. The tadpoles develop rapidly so that on the coast young tree frogs are ready to leave the water by mid-July.
After leaving the water tree-frogs spend most of their life in shrubs and trees. Here they climb with ease, leaping from place to place and clinging to smooth surfaces, such as shiny leaves, by means of the adhesive pads on the toes. Their main food preferences are various insects which they catch with great skill by means of their sticky tongues. The male’s croak at this time is a grating sound not unlike the noise produced by dragging the finger-nail over a few inches of fly screening.
Adult Pacific Tree Frogs eat spiders and a wide variety of insects, which they hunt while climbing about on plants. Tadpoles graze on algae and detritus. In turn, tree frogs are preyed on by snakes, bullfrogs, and many birds and mammals, and tadpoles are eaten by larger frogs and fish.
The general form moderately slender, length 5 to 7 centimeters, the head is broader than it is long. The eyes are moderate with a horizontal pupil, the ear membrane is small, about one-half the diameter of the eye. No parotoid gland, and the dorsolateral fold not prominent. The front and hind legs are long and slender. The heel of hind leg when extended forward extends beyond the snout. The hind toes are fully webbed; the skin is smooth, sometimes displaying small tubercles, particularly on thighs.
The colour on top is light brown, sometimes with reddish tinge and usually with small, irregularly shaped dark spots on the head and body, a dark patch from eye to the corner of the jaw, and a light line along the upper jaw from a point below the eye to skin-fold behind the angle of the jaw. The hind legs may be speckled or barred with dark brown, the under-parts are light with dark mottling, a conspicuous red coloration displays on the side of the body and under-surfaces of fore and hind legs.
The Red-legged Frog may be recognized by its slender form, smooth skin, dark patch behind the eye and red colour on the sides of the body and under-surfaces of the legs.
Along the Pacific Coast from British Columbia to extreme north-western California, In British Columbia the Red-legged Frog is known only from the south coastal region, west of the Coast Mountains, including Vancouver Island.
Habitat and Habits:
The Red-legged frog is an inhabitant of woods, banks, streams, and shorelines of lakes. In these surroundings it is usually seen only when it is disturbed, at which time it may leap a considerable distance into the water and swim rapidly to the bottom. After a time, if the observer is patient, the frog may be seen floating to the surface and may be easily taken in a net.
The eggs are laid in masses during March and April in backwaters of lakes and streams. Tadpoles transform in mid to late July. Life span can be up to thirteen years.
Adult Red-legged Frogs feed happily on insects and other small invertebrates, which they hunt along the edges of streams and ponds. Tadpoles graze on algae.