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Keeping Backyard Biodiversity Outdoors

By: Victoria Badham, Education & Outreach Manager, Toronto Wildlife Centre

It’s March! Spring is only a few short weeks away and wild animals are already prepping for the next generation of wild babies (and some are already here!).  Building the perfect den or nest is critical to successfully raising young and wild moms often find optimal spaces in human-built structures such as houses. And although many of us appreciate seeing our wild neighbours in our yards, having a wild family move into your home can be less appealing. So, read on to learn more about how to wildlife-proof your home.

1. Check your roof

Raccoons and squirrels will target roofs that are in need of repair. If you find a potential point of entry, it’s important to make sure the den is vacant before you begin sealing it off.  There’s a simple 3-step test you can perform to make sure an animal den is vacant. Before sealing any holes in your home, perform the Paper Test:

  • Block the entry point: If you have not seen or heard any animals inside the space, block the entry point with something that an animal could easily move, such as a thin piece of paper taped loosely over the hole or scrunched up pieces of paper placed inside the hole.
  • Wait it out: Leave the paper in place for 72 hours (since some animals do not leave their dens every day).
  • Seal away! If the paper is unmoved after 72 hours and there is no other reason to believe the den is occupied, it is safe to seal it.

One way doors should never be used if there is a chance that there are babies inside that are not old enough to leave the den site (this can occur as early as late winter). One way doors allow mom to leave but she won’t be able to get back in to retrieve her babies.

2. Cap your chimney

A variety of wild species will make use of your chimney for a den or nest.  TWC’s Wildlife Hotline occasionally receives calls requesting help with a baby bird, squirrel, or raccoon that has fallen down to the bottom. And there is always the risk that someone could use the fireplace, not knowing animals are inside. The best solution is to:

  • Install a chimney cap—pre-fabricated caps are sold at hardware stores
  • Avoid caps that have a gap below the top of the cap as some wild animals can put their paws inside this gap and pull the wire sides down
  • If using a homemade chimney cap, ensure there are no gaps in the mesh and cinch the sides tightly around the chimney so that animals cannot pull the cap off

3. Install vent covers

Like chimneys, vents offer cozy spaces for cavity nesting birds like starlings and sparrows. Vent covers can be purchased at your local hardware store and are easy to install.

Remember that birds only use holes like these when they are nesting, so if you see an adult using a vent during spring and summer, you should always assume that there are babies inside.

The nesting season for songbirds is very short. Most baby birds leave the nest when they are only 14-21 days old! Once they leave the nest, they don’t go back again—birds only use nests to raise their babies in. When the babies leave, the nest can be cleaned up and the entry point sealed up to prevent future nesting.

Since nesting birds don’t usually cause any damage or pose any danger, we recommend waiting the short 2-3 weeks until the babies have left the nest on their own. (Photos:

4. Cover window wells

Open window wells are not only a welcome den site for good climbers, like raccoons, they also pose a hazard for adult animals that can easily become trapped in them, like skunks and opossums. Window well covers are commercially available in a wide range of options.


5. Never trap and relocate

If a wild animal does find its way into your attic, shed or garage this spring or summer, never ever trap and relocate. Contrary to popular belief, this is not a good way to solve the problem. Relocated animals seldom survive the move, and during spring and summer, many trapped animals are mothers with babies tucked away somewhere; once she’s moved to a new location, there’s no way to reunite her with her babies, orphaning them. Humane harassment techniques, which include sight, sound and smell deterrents are effective and humane and keep wild families together.

To learn more about wildlife-proofing your home, please visit our website at

Supporting #backyardbiodiversity in partnership with Local Enhancement & Appreciation of Forests and Ontario Power Generation.