Robyn Williams: Dogs. The Science Show is very fond of dogs, and we've always wondered when they and therefore dingoes first came to Australia. Euan Ritchie, who has been studying the role of dingoes in the modern Australian environment, agrees dogs came to us at least 4,000 years ago from the north.

Euan Ritchie: Yes, there has been an interesting kind of update on the story about human arrival in Australia and potentially the role that people from India may have had, this has been going backwards and forwards quite a bit and so people have been looking at that. And the dingo is implicated in that of course because the dingo came from somewhere in Asia probably roughly 3,500 to 5,000 years ago.

Robyn Williams: And the idea might be that they brought the dingo or dogs with them?

Euan Ritchie: Exactly, yes. So the dingo is thought to derive from the Asian wolf, a semi-domesticated dog in Asia, and that it came to Australia, and that it became wild again, if you like.

Robyn Williams: The images of actually bringing a dog with you on a canoe or some other boat…of course the legend has it that they used them if the sharks got too close and you could turf the…or else eat the bloody thing. Why would they carry dogs with them, do you think?

Euan Ritchie: Dogs are obviously very efficient hunters but dogs are also companions. We know that humans and dogs have had a relationship for many thousands of years, so they have multiple uses to humans.

Robyn Williams: Your own studies looking at the place of the dingo in our Australian landscape, is it a different kind of role at the moment?

Euan Ritchie: Yes, so what we're looking at now is whether they actually have a positive benefit for biodiversity, and I guess to give some context, Australia really has a huge problem with its biodiversity, we've lost more than 24 mammal species since Europeans arrived. And you may know as well in northern Australia right now there's a whole range of mammal species that are in decline and we think it's for a whole range of reasons but including feral cats. And many scientists are really concerned that we're about to see the next wave of mammal extinctions, which are already on top of quite bad ones in the past.

Robyn Williams: Yes, the cats have been shown quite recently to have a gigantic effect really, killing native birds and suchlike.

Euan Ritchie: Yes. There was an estimate done just in the US recently where they estimated that cats kill several billion mammals per year, not to mention many, many billions of birds as well, and it's something that's probably quite similar in Australia. We know that there are many millions of cats in Australia and one cat can kill more than 10 animals per night quite easily. So they don't just kill to eat of course, they kill in surplus.

Robyn Williams: So would the dingoes make it worse or make it better?

Euan Ritchie: Well, it's a strange situation I guess to use one predator to fix a problem that of course is with another predator, but what we know from around the world is that top predators or apex predators as some people call them are quite useful in controlling other species. And so dingoes actually don't like cats very much, and of course you can think about your neighbour's cat, if you've got a dog they're not going to visit your yard very much. And so dingoes do a very good job of both killing cats, but of course cats, being scared of dingoes, then actually do their best to avoid them.

An interesting piece of work by one of my PhD students has found that where dingoes are present and abundant, cats are much less active, and they are active in a smaller part of the night. And what that means is I guess it gives a leg-up to the native mammals. Cats are still there but they are much less active than they otherwise would be.

Robyn Williams: Where was this study done, which part of the landscape?

Euan Ritchie: This was done in northern Australia, right across the top. So we had study sites in south-west Queensland, Central Australia, Western Australia, so the Great Sandy Desert, right across the top. So we've got sites from a range of environments. We're seeing a consistent pattern that where dingoes are present, cat activity is much lower.

Robyn Williams: How do you measure that though?

Euan Ritchie: That's one of the great inventions that has come on recently to science is the invention of camera traps. Previously it was very hard to survey predators, they are very cryptic by nature and very low abundance. But using remote camera traps we can put these cameras out in the field for two months or more, and as animals walk past we can see how many there are and what they're getting up to. So we are now getting really good information about what cats and dingoes are doing.

Robyn Williams: So the dingoes are keeping the cats away or are they in fact attacking them or what?

Euan Ritchie: They do both. We know that they kill them. We've seen cat in dingo diet, so we know that dingoes do actually kill and eat cats, but what we also know is if you look at activity through these cameras over a 24-hour period, where dingoes are present cats only come out much later in the night, so at one, two, three in the morning when dingoes are less active. What happens is when you get rid of dingoes through poison baiting and shooting, cats become much more active just post dusk which is when a lot of your small mammals and your reptiles are most active, which means it's kind of like a double-whammy effect for those small animals. Cats are there but there are also more active at the worst time for them.

Robyn Williams: Which are the native animals are most in danger in that regard?

Euan Ritchie: Well, not surprisingly I guess it's very similar to the past. A lot of our small marsupials…so phascogales which is kind of a small insectivorous mammal, a lot of our rodents, a lot of the same species that have been heavily affected in the past, but also things like geckos and things like that as well.

Robyn Williams: Okay, so what would you say in terms of policy should be done? Because, you know, in America they are bringing back the wolf, with mixed success because some people are still prejudiced, they are worried about the fact that their stock is going to be attacked by wolves. Is there the same kind of dicey business regarding the dingo?

Euan Ritchie: Look, it's an excellent question, and there's no doubt that dingoes have negative effects as well. They can certainly cause huge stock loss. I guess the problem at the moment is we've been doing the same thing for a long time and biodiversity is going backwards. So instead of, say, shooting dingoes, how about potentially using things like guardian animals to help graziers protect their flock, but at the same time we can still keep predators in the landscape. And the great thing about that is that predators essentially are doing the work of pest control for free. So they are going around killing foxes and cats and keeping kangaroo numbers low, all for free, 24 hours a day, seven days a week, where at the moment we're spending huge amounts of money, millions of dollars a year controlling pest species, things like rabbits, cats, kangaroos, where dingoes could essentially do that for free. So if we can use things like guardian animals to our benefit to help the graziers and at the same time have dingoes, we've obviously got a win-win situation there.

Robyn Williams: I know you go out into the field, but have you actually been up close and familiar with dingoes?

Euan Ritchie: Yes, I've actually been very close. In a lot of the areas where dingoes are not being heavily persecuted they are actually not that shy and they will actually walk very close to the car, and they are stunning animals, beautiful animals. I'm not sure if you've ever had the experience yourself of seeing one in the wild but it's quite a stunning image to see a dingo in the wild.

Robyn Williams: Sure, but the thing with dogs is they've been bred to be kind of glorified puppies. That's the sort of juvenile stage, it's kind of built-in, whereas in dingoes I would imagine they would be going back to the wolf stage where they are adult and distant?

Euan Ritchie: Yes, dingoes are indeed much more wolf-like than, say, like you said, a dog, so that's very true. But they still actually are quite inquisitive animals by nature. Having said that of course, the ones that tend to be less inquisitive are the older ones, and that's probably why they've survived for so long because they've managed to avoid humans. Often the ones that do come up to you to say hello are the pups.

Robyn Williams: Yes, delightful creatures, as my late colleague Alan Saunders always felt. That was Euan Ritchie who lectures in ecology at Deakin University in Victoria.