Sadly under the law, rabbits living in the wild whether they be abandoned or not are by definition "wildlife" however as soon as they are contained they are considered "domestic".

The SPCA doesn't have jurisdiction over wildlife unless granted a specific government permit so they can only advise or suggest to the Provincial government agents on such matters as the most humane way to euthanize wild animals.

Once again it's the fuzzy grey area for the buns.