Guest IMHO has a point. When does a non-native plant or animal become so much a part of the local biosphere that it becomes essentially native?

White tailed deer are not native to Nova Scotia, but have been here hundreds of years. No one suggests getting rid of them. Coyotes (or Brush Wolves - these are not your tiny Western coyotes) are relative newcomers, and it looks like they may turn out to be the predator the deer need to remain a healthy population. Yet many people are up in arms about coyotes and want to see them eradicated.

The salt rose is a beautiful big bush, a favourite of birds, a good erosion controller, a scent of summer. It isn't native, but has been here a couple hundred years.

Our beautiful hardwood stands, mostly of maples, birch, poplar and ash, are a modern forest. Long ago, Nova Scotia was covered in expansive forests of Beech.

There likely isn't a cubic metre of decent soil in North America that doesn't have your ordinary earthworm tunnelling through. They aren't native, and in fact are a scourge of people trying to rescue prairie grasslands. But your average eco-warrior is enthusiastic about earthworms.

Encouraging fragile natives in your gardens is most likely a great idea. Being dogmatic about it could lead to some questionable decisions.