This is a young field mouse, either White-footed mouse or Deer mouse (they are very similar and both occur in the Ottawa area) found at the Fletcher Wildlife Garden.

That wee bit heap o' leaves an stibble,
Has cost thee mony a weary nibble!
Now thou's turn'd out, for a' thy trouble,
But house or hald,
To thole the winter's sleety dribble,
An' cranreuch cauld! Robbie Burns, "To a Mouse".