Many areas have that restriction. I forget where that info is available though.
For Ontario; You find it in hunting regulations.
For small game, It goes not by WMUs but by townships.
A person hunting small game may not carry or use a rifle
of greater calibre than a .275-calibre rifle, except a muzzleloading
gun, in the geographic areas of Brant, Chatham-Kent,
Quote: "Durham, Elgin, Essex, Haldimand, Halton, Hamilton, Huron,
Lambton, Middlesex, Niagara, Norfolk, Northumberland,
Oxford, Peel, Perth, Toronto, Waterloo, Wellington or York."
For N.S. I don't know but, I'd check N.S. hunting regulations.
Edit.
Have a look at
http://novascotia.ca/natr/hunt/pdf/HuntingSummary_2014.pdf page 93 and on
I glanced at it and; I think that any centerfire is a no go for small game in NS.