If you hit a kangaroo (I have only ever had a side on collision where the kangaroo jumped into the side of my car and bounced off) you need to get out and check if it has a live joey (baby kangaroo) in its pouch. You are not allowed to keep the joeys, but there are organisations that will take them in and raise them enforce release back into the wild.
Note: If you see a kangaroo (or any marsupial) dead on the side of the road, if it has a pink squiggle spray-painted on its side, someone has already checked it for a joey - so you don't have to try stick your hand into a gooey mess.
