Georgian Bay Islands National Park of Canada
MAJOR HABITATS FOUND IN GEORGIAN BAY
OPEN EXPOSED AREAS
Smooth rock shoreline of Georgian Bay Islands National Park of Canada© Parks Canada/ W. Waterton/ Collection GBINP
The exposed rock outcrops, so characteristic of Georgian Bay, are home to a limited group of plants and animals. Because of exposure to winds and desert-like conditions, the plants which grow here are often low-growing and adapted to drought conditions.
A key life form here are lichens which cling to the bare rock, resembling patches of mould on bread. Each different colour and texture usually represents another of the dozens of species present. A unique combination of algae and fungi, lichens do not need soil to grow, and thus are some of the first plants to colonize an area. They produce weak acids which gradually break off small fragments of rock which are washed by rain into cracks and crevices where they become the beginnings of soil. Carpets of reindeer moss (actually a kind of lichen) grow vigorously in the spring, or after a rain, and then curl and shrink against the rock during the summer heat. Rock tripe or bat's ear is a conspicuous brown ear-shaped lichen which often grows on the sides of huge rocks.
Despite the desert-like environment created by the sun's heat radiating off the rock, other plants will grow here once a little soil has accumulated in the crevices and depressions. Next to colonize after the lichens are mosses, grasses and other small, hardy plants. These plants include rock spurge and rock cres, and in places where people have lived - mossy stonecrop. The yellow and pink blooms of pale corydalis or the nodding red flowers of columbine, a member of the buttercup family, are welcome sights in the spring and early summer. Bristly sarsaparilla (pronounced sasparilla), named for its thorny perennial stems is an example of a plant found on both rock outcrops and on the dry sandy soils of disturbed areas.
Serviceberry (saskatoon), lowbush blueberry and meadowsweet are shrubs commonly found in the shallow soil pockets. As adaptation to the strong winds, a creeping variety of common juniper is also found here.
One usually doesn't associate ferns with dry, almost soilless conditions, but there are two ferns typical of the Shield which are found here: marginal shield fern and polypody. Polypody is one of the first ferns to invade an area. While it is more hardy than most ferns it is usually found growing on rock faces where water seepage occurs.
Of the trees that can stand these rigorous conditions, the most characteristic are white pine and scrub red oak. We also find red juniper, a tree which is often misnamed red cedar because of its resemblance to the latter. It is immediately recognized as a juniper, however, by its strong smelling bluish "berries." More commonly found further south, red juniper is another of the anomalies of Georgian Bay.
Atop the exposed outcrops, plant growth is stunted by the lack of soil and by exposure to the winds. The effects of the prevailing northwesterly winds upon vegetation is so pronounced that the windswept silhouettes of the white pine have become a symbol for the islands. Often these small, gnarled pines and their deciduous counterparts, the red oak, are hundreds of years old - quite a contrast to their tall, straight sisters which grow where soil is adequate.
Although the rock outcrops themselves do not shelter many animals, the borders between forest and rock are alive with bird life. The prairie warbler, a southern bird relatively rare here in Canada, nests in junipers which grow in these areas. The common nighthawk also uses the open rock to nest. Although this bird has adapted readily to city life where it uses rooftops, its natural nesting grounds are rocks such as are found all over the Bay. Pine warblers, which nest only in pines, and the rufous-sided towhee are two other birds associated with this habitat.
The fox snake, a constrictor which emits a fox-smelling musk when bothered, is among the animals who prefer this habitat. It feeds on mice and chipmunks and is associated with the vegetation pockets found between the outcrops. The rare five-lined skink, our only lizard, and the diminutive ring-necked snake just about complete the list of cold-blooded inhabitants. Contrary to our usual image of snakes, the ring-necked snake is a small and delicate animal coloured a beautiful cobalt blue with a thin yellow ring around its neck. Like the fox snake, this snake is associated with the hardwood pockets found in the "valleys" between some of the outcrops. Both snakes, however, can be found sunning out on the rocks.
Beaches and Disturbed Areas
Despite the thousands of kilometres of shoreline along Georgian Bay and its more than 90 000 islands, beaches are relatively rare. Sandy beaches are restricted to the east sides of larger islands such as Beausoleil or Giant's Tomb. Rounded cobblestone beaches are found along the west exposed sides of some islands, but are also uncommon.
Of the birds that nest here, the most noticeable and abundant is the noisy killdeer. Most of the other birds found here are associated with spring and autumn migrations: sanderlings, dunlins, horned larks, water pipits and snow buntings.
Most turtles lay their eggs in the sand, although they do not remain here. The rare hognose snake has a special adaptation which equips it to catch American toads, which it feeds on almost exclusively. When the toad puffs itself up to discourage its predators, the hognose deflates it with a special tooth.
In the small pools of water commonly found along the beaches, cattails, sedges, boneset, horsetails and blue lobelia thrive. Many frog species, including the eastern gray treefrog, use these pools for breeding so it is important not to fill them in.
Along beach fringes, leopard frogs, meadow jumping mice and meadow voles, the most common rodent in southern Ontario, find cover in the long grass. Further up in the aspens, balsam poplars, sumacs, chokecherries and hawthorns nesting birds such as catbirds, robins, brown thrashers, song sparrows and kingbirds can be found.
Because many of the existing beaches have been intensively used for recreation, it is common to find introduced species (i.e. weeds) here as well. There are the same species which thrive in vacant lots and along roadsides: mossy stonecrop, St. John's Wort, milkweed, dandelion and hawkweed. Poison ivy is an example of a native plant which thrives in disturbed areas.