This isn’t the only solution, but it is one way to help. When adding or replacing plants in a yard or garden, make an effort to use as many native species as possible. Native birds need native plants to survive. The plants need to be native to a particular habitat. A Colorado spruce is not native to southern Ontario.
In southern Ontario, there is a narrow strip of Carolinian forest zone, which stretches from Niagara Region and Windsor right down into the southern United States. People living in this unique ecological niche can grow a wide variety of plants, but this has a negative effect by enabling people to grow many exotic plants. Instead, people should increase biodiversity by using native species.
Here are a few examples of Carolinian trees and shrubs that would be much better for this area’s ecology: pawpaw (Asimina triloba), sassafras (Sassafras albidum), tulip tree (Liriodendron tulipifera), Kentucky coffee tree (Gymnocladus dioicus), spicebush (Lindera benzoin), eastern hemlock (Tsuga canadensis), witch-hazel, flowering dogwood and eastern redbud. There are many more.
Among the hundreds of native Carolinian Zone flowers are jewelweed (Impatiens pallida), trillium (Trillium grandifolium), Dutchman’s breeches, jack-in-the-pulpit, blazing star, wild bergamot, bee balm and black-eyed Susan. Many, like the wildlife that depend on them, are endangered. (Be careful planting some in an area frequented by pets, because some are toxic.)
Check with a local conservation organization for names of plants for specific ecological zones. You will be surprised by the variety of plants available.
Another way to help is by being very careful with the use of chemicals on your farm, lawn or garden, especially herbicides and insecticides. Look for natural controls whenever possible to avoid poisoning birds.