"We do not have solitary beings. Every creature is in some way connected to and dependent on the rest."
— Lewis Thomas
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Take a deep breath. The oxygen in your lungs comes from plants and trees all over the Earth. At the same time, you share that oxygen with countless creatures on the planet. Now, pour yourself a nice, cold glass of water from the tap and think about where it comes from: rivers, lakes, subterranean streams, marshes, plants, and clouds. Now peek inside your lunch bag. Everything you see — fruit, cheese, bread, cookies, baloney, couscous, you name it — comes from other living things. You not only take up nutrients; you also release wastes. Your life is inseparable from the ecosystem you live in. Every species interacts with the air, water, sun, soil, and living things that sustain it in a huge web of interdependency.
The cities and highways we build are just as much part of the ecosphere as wildflowers and butterflies. And though we create amazing things, we are still just one of the millions of species sharing the Earth.
A World of Interdependency
Interrelationships are best illustrated by food webs — for instance, a boreal forest food web. In this vast, coniferous forest, which covers over 30 percent of Canada, wildlife exist in a complicated balancing act of interdependency.
Even if that balance is upset, it soon bounces back. For example, if a meadow vole population produces too many young, its food will disappear and many voles will starve to death. But as the population declines, wild grasses grow back. Eventually, voles and the plants they eat regain balance.
Luckily, vole populations are largely kept in check by predators like the great gray owl: the largest and rarest owl in Canada. This vulnerable raptor inhabits the deepest, darkest bogs of the boreal forest. As more meadow voles populate these bogs, the great gray owls can reproduce more. However, if there are too many owls and not enough voles, some great gray owls will die or go searching for happier hunting grounds. Then, the number of voles will go up again. Gray owls also eat shrews. Shrews eat larch sawfly larvae, which disfigure larch trees. Meanwhile, the owls occupy the abandoned nests of ravens, crows, and hawks, many of which, by the way, are built in disfigured larches.
Improve Conditions for Keystone Species
Some creatures, like prairie dogs, arctic cod, songbirds, flying squirrels, and snakes, hold more vital positions in their ecosystems than others. Just as the loss of a keystone from an arch can cause a bridge to tumble down, the loss of a keystone species can cause a whole ecosystem to collapse.
- Prairie dogs not only are a food source for many predators, they also provide homes for species like the endangered burrowing owl by digging tunnels.
- In its dual role as predator and prey, the arctic cod transfers food energy from a lower point in the food web — from algae-grazing crustaceans called amphipods — to marine mammals above.
- Without songbirds to devour multitudes of destructive insects, forests could not exist.
- Through their feces, flying squirrels spread mycorrhizal fungi, vital for the growth and reproduction of trees, throughout forests.
- As an important link in many food webs, snakes eat grubs, slugs, and mice, among other creatures, while providing food for predators.
You can make life easier for keystone species like prairie dogs and arctic cod by raising public awareness to their importance in your area. The projects that follow are designed to help songbirds, northern flying squirrels, and snakes.
Give Owls a Squatting Spot: Great gray owls are squatters. They raise their young in the vacant stick nests of other birds. But nests within suitable habitat are scarce. If you’d like to help out these forest "phantoms," provide them and their cousins — long-eared, barred, and great horned owls — with nesting structures.
Adopt a woodlot for songbirds: The scarlet tanagers and black capped chickadees you see flitting around wooded areas are very important to the forest ecosystem. Without birds to feed on leaf munching insects, trees can perish. In return, birds get food sources and nesting sites. Sadly, songbird numbers are plummeting — largely because of habitat loss in Canada and in the songbirds' wintering grounds down south. Do a good turn for birds and trees, and the web of life they support: adopt a woodlot. But, be sure to seek permission from your municipality or a landowner first.
Save snags: Snags provide crucial nesting and perching sites for everything from flying squirrels to ospreys. They're most desirable near water, forest edges, and brush piles. Post signs on snags to alert people to retain them for the benefit of wildlife.
Carve me, not a tree: Never harm a living tree by removing its bark or carving marks into it. Instead, protect the trees by putting up a "carving post" in your woodlot for the use of passers-by hankering to leave their mark.
Enhance a forest edge: Forest edges give animals access to two habitats. For example, the boundary between a woodlot and meadow gives deer the cover of trees and grasses to eat. Enhance forest edges by increasing their thickness thro ugh succession — the natural growth of an ecosystem — or increase the diversity of foods by planting fruit- and nut-bearing trees, shrubs, and vines. Hickory, Saskatoon-berry, and grape are among the most beneficial species you can plant for wildlife on sunny woodlot edges.
Protect northern flying squirrels: These sprightly gliders are crazy about mycorrhizal fungi. And since their droppings contain fungal spores, flying squirrels play an important role in spreading mycorrhizas around the forest. That's good news for fungi and for trees. Many trees are interdependent with mycorrhizas, which grow on their roots, boosting their growth and reproduction.
Both the northern flying squirrel and its imperilled cousin, the southern flying squirrel, readily move into artificial structures built for other species (like chickadees and nuthatches), especially where snags are in short supply. Place nesting boxes 3.5 to 4 metres above the ground, in a heavily wooded area to avoid competition from house sparrows. Entrance holes should be 3 centimetres in diameter.
Put up Nesting Shelves: Although birds such as robins, phoebes, and barn swallows won't nest in boxes, they'll gladly accept nesting shelves tucked under eaves.
- Use 2-centimetre (3/4-inch) untreated softwood or any wood that resists weathering. This structure can be made easily out of leftover lumber. Never use pressure-treated wood; it can be toxic to nestlings.
- Follow the construction plan laid out below. Cut the roof, bottom, sides, back, and front for the nesting shelf.
- Assemble the pieces according to the construction plan, using 4-centimetre (1.5-inch) coated flat-head screws. The structure will last longer if you hold the pieces together with bond-fast glue.
- Either leave the nesting shelf unpainted or treat it with waterproof varnish. If you paint the structure, use brown, tan, or grey, as birds will more likely be attracted to such colours.
- Mount the nesting shelf beneath the eaves of your school, at least 4 or 5 metres away from a doorway.
- Remove nests as soon as the young can fly. Robins, for example, build nests each year and often twice in summer. Removing the nests keeps them from building another one on top of it.
- Provide nesting materials by hanging from a tree a mesh onion bag stuffed with dried grass, cotton, wool, feathers, twigs, and so on.
- Check on a regular basis that the nesting shelf is mounted securely and is in good repair.
Give Snakes a Winter Home: Snakes are an important link in many food webs. They eat grubs, slugs, mice, and birds, while providing food for owls, hawks, and predatory mammals. As land is covered with buildings and parking lots, snakes lose their habitat, including the subterranean dens in which they over winter. A terrific project to undertake in partnership with your community is to provide a hibernation den for these fascinating and beneficial animals.
- Dig a hole 2 metres deep and 1.5 metres square in a moist, sunny clearing next to a woodlot.
- Loosely fill the pit with stumps, branches, brush, and boards, mixed with soil and leaves.
- Cover the pit with a 1-metre mound of brush, soil, and leaves to provide insulation as well as protection from predators.
- Some snakes hibernate in rock mounds and cavities. You can accommodate them by filling a pit, as described above, exclusively with large rocks.
© Canadian Wildlife Federation
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