My kid and I heard a call that was definitely not one of our usual neighbourhood birds. Then we saw a small brown-ish hawk fly away from a branch above us, leaving a second one behind. We could see the narrow tail as it sat on the branch. While I ran inside to get binoculars, the second one flew off, showing a very dark back with the white flash on the rump. The obvious choice is Northern Harrier, which do pass thru Ontario in late fall. I couldn't find any local sightings since Sept, but that is an unusual time for them, this is a common one.The normal call is somewhat different, but on ebird I heard a version similar to what we heard - a rusty rumbly threepeat like "ehh - ehh- ehh". I am always pleased to have someone else confirm a sighting or share it.