Shirley Wong

Kangaroo, oh.

I'm back in Jindawi in the eastern state of Queensland, and I'm walking along the dingo fence with Doug Henning.

The fence is maintained by a team of patrolmen who divvy up the length and each take care of a section.

Doug pointed to a hole that had been patched over.

Yeah.

Okay, I see that, yeah.

Okay, yeah.

What kind of animal would have made that hole?

Or echidna?

All along the fence, there are large dents where the wire has been caved in.

So what are the dents that we see in the fence?

From running into it?

They run into it hard enough that it dents it?

The animals of the outback damage the dingo fence all the time, but that's nothing compared to the damage the fence does to them.

But one of the biggest effects the fence has had on the environment was just removing the dingo from a massive chunk of the continent.

As Australia's apex predator, the dingo kept other animal populations in check.

And when the dingo went away, it set off a cascade of ecological consequences.

That's ecologist Thomas Newsome again.

He says that because there are no dingoes eating them, there are actually too many kangaroos in Australia.

Yes.