- I live on the Morington Peninsula. On the clifftops overlooking the beaches and on my property there are lots of places where there are extensive networks of tunnels. They are small, 60 mm round, just under the ground cover or just under the soil by 0.5 to 1cm. I see what I think are black rats occasionally come out of these. But I have never read of them making such networks of tunnels. And they are extensive. Ranging over 20 metres. Can you tell me anything about these tunnels and what may be making them?