I live in Ottawa, Canada. I moved into my house a year ago. I've noticed on
my lawn that there are a bunch of little mounds of dirt, around 2-3 inches
in diameter, and only about 1-2 inches high, but enough for the lawn to
feel very rough. There are probably one of these mounds every 2-3 feet.

I'm trying to figure out why these are here. I don't see ants coming in or
out of them so I don't think they are anthills.

Any ideas?

Rene