We live on the southern edge of the Canadian Shield where the spectacular scenery of our hills, valleys, and lakes is the result of the undulating nature of the Precambrian rock lying under us. An abundance of exposed rock surrounds us, not just on our windswept shorelines, but also on the tops of inland rocky domes and in flat areas called barrens. It can appear windswept, dry, baking hot in the summer and seemingly devoid of life. A close look, however, reveals little oases of life near rock crevices, flat stone slabs, and depressions. These provide shade, hold moisture, and let organic debris collect, allowing life forms to get a foothold.
The little pockets of life are the first stages of primary forest succession, the change over thousands of years from bare rock to forest. The first living forms to colonize bare rock are lichens appearing as variously coloured crust-like growths. These primitive plants are comprised of algae cells and fungus living closely together, providing each other with essentials for life. The algae, through the chemical process of photosynthesis, uses carbon dioxide from the air, and water held by the fungus to store the sun’s energy in a fundamental building block of life, glucose. Lichen anchored to the rock and natural weathering contributes to the erosion of the rock into smaller particles necessary for soil building. Next, mosses and grasses get a foothold, and as more soil forms, herbaceous plants appear, followed by shrubs and eventually trees. On the shield we can find all these stages of plant succession.
The White Pine is an example of a tree adapted to life on the rocks. It can grow in a very thin soil layer and some seem to grow right out of the rock, The roots can get nutrients, moisture, and physical support from even the smallest of cracks, resulting sometimes in an amazingly large tree.
A wildflower associated with flat rock outcrops near forest edges, often growing from small pockets of moss, is the Pale Corydalis. The rather delicate leaves are a pale grayish green. The flowers are a particularly attractive combination of pink and yellow, an unusual colour mix for wildflowers. Even a seasoned naturalist will stop to admire them and point them out to others. They are fairly common, easy to find, and one of the most spectacular of our June flowers. Some very interesting and uncommon animals can be found on our rocks.
With its high heat capacity, rock is warmer than the surroundings in the fall. On cool fall days the Eastern Hognose Snake may be found sunning itself on rock surfaces. The Hognose, named for its upturned snout, is a robust snake usually pale brown with darker patches, although it can be quite variable in appearance. Usually it has a dark patch on each side of the head behind the eye. It is totally harmless to humans, has no fangs, and lives mainly on a diet of toads. When it feels threatened it tries to scare a potential attacker by flattening its head like a cobra and hissing and feigning strikes. This will usually scare off dogs and other curious animals. If the puffing doesn’t work, as a last resort the snake will roll over and play dead and, if flipped upright, it may roll over again and resume playing dead, a comical behaviour. In spite of its harmless nature, the hissing and puffing can look very threatening to persons unaware of this behaviour and as a result, many are killed. Human persecution and road kills has led to this snake, and other Ontario snake species for that matter, being listed as Threatened Species by the Ontario Ministry of Natural Resources (the MNR). If you see an Eastern Hognose Snake, you are very lucky. Take pictures, and then let it be. If necessary, coax it off any roadway, and please report your sighting to the MNR in Parry Sound.
On larger rocky outcrops with lots of small flat rocks laying on it, look for the five-lined skink. This reptile is Ontario’s only species of lizard and most of the Canadian population is in the Parry Sound/Muskoka area. Juveniles are most striking with five white or yellowish stripes running lengthwise along the body and a bright blue tail. As they mature the stripes fade and become less obvious and the colours turn beige or grey in adults. An adult male has a bright orange chin and jaws in breeding season, during the spring. They usually feed on invertebrates, including crickets, grasshoppers, and spiders. It is not uncommon to see them sunning themselves on warm days, but if approached they will dart for cover, with lightening speed, under the flat rocks or into crevices. You get the best looks at them in cooler weather when they move much more slowly and may even remain motionless, but in cool weather they remain under cover and to find one it is necessary to lift up and check under many rocks. It is best not to try to catch them because the tail is easily broken off. This characteristic allows them to escape predators who may be left with only a wriggling tail for their efforts. They eventually grow a new tail. Fairly common in our area, but rare elsewhere in Ontario, the fi ve-lined skink is listed as a species of Special Concern by the MNR.
Ontario has just seen the completion a second Breeding Bird Atlas. Volunteers canvassed the province each spring and early summer over a five year period to record which bird species were present and breeding. Because this is the second atlas, the first being 20 years ago, certain trends have been discovered. There has been a significant decline in aerial foragers, birds that catch flying insects, such as the common nighthawk. Nighthawks roost during the day on the ground in open areas such as rock outcrops. They are most apparent at dusk when they start to feed and make a loud nasal “peent” call as they dart about in the sky, mouths agape, catching insects.
They are voracious feeders and a single nighthawk was found to have 500 mosquitoes in its stomach. In the past, the call of the nighthawk was an expected sound on warm summer nights. Now it is rarely heard. They nest naturally in open areas like rock barrens, and have also adapted to flat gravel covered roofs of buildings in towns and cities.
The accompanying photos are of a female common nighthawk and the eggs she was sitting on. From the photo of the eggs you can see that nest construction is minimal. The bird’s plumage blends in with the surrounding rock and, when settled on the eggs, she is practically invisible. On a Parry Sound Nature Club outing we accidentally fl ushed her from the nest and she fl ew only a few feet before alighting close by. We took a few photos and then left her to return to the eggs. Hopefully, studies are under way to determine why nighthawks are declining. They are considered a threatened species in Canada.
