HI Guys.
Now admittedly this was a fair while ago but I lived on the airport at YMIA between 1984 and 1990 (across from the BOM building for anyone who knows the airport) and I can tell you there were no shortage of places for roos to enter the airport boundry as the fences were only waist high wire strand fences.
As I said its been a while but I have been back a number of times and each time nothing had changed. Poor old Les the groundsman was forever chasing them away. I was always surprised there were not more problems with roos than there were.
Fly safe
Play hard
Regards Hoss