The strange case of cats and dingo dogs
When predators wipe out native populations, then the hounds of hell might have to be unleashed, as many islanders know. The world's biggest island, Australia, has long battled the rats, cats, rabbit, fox and dog predation on their native fauna and flora.
The wild dingo (Canis lupus dingo) is another kettle of fish. Being resident for as long as native peoples, as a species, it seems more at ecological peace with its environment, being particularly good at disposing of alien sheep! This new paper from Leila A. Brook, Christopher N. Johnson and Euan G. Ritchie of James Cook University, Deakin University and the University of Tasmania, all in Australia, proposes that the wild dingo is well able to control the predations of cats in the evening, when it is most likely to be active itself. Fox control is also likely.
It's called the top-down control of meso-predators, but it certainly gets on the cats' nerves. When dingoes are exterminated, the cats come out at night, according to the carefully set-up nine camera surveys carried out in Northern Australian rangeland properties. Leila Brook explained, "This design allowed us to measure the effects of predator control on dingoes, and test how reduced dingo numbers might affect feral cats."
The dingo was a dawn and dusk animal when uncontrolled, catching larger animals which were abundant at those times. When these dogs were shot or killed by 1080 poison baiting, they gave up the evening shift and only came out at dawn normally. This gave the cats the opportunity and they certainly had the inclination. On cam, the cats avoided areas where dingoes were locally common.
This means the smaller prey survived better there, as dingoes were not interested in them. The native biodiversity would certainly be affected and we need now to know how much? The authors put forward the point that predator control might be doing much more than simply reducing numbers. It was adjusting the dingoes' behaviour to make it less effective as the top predator. To put it as plain as a pikestaff:
"Dingoes and feral cats both eat nocturnal mammals that come out at dusk. Where dingoes were left alone, they were mainly active in the evening and at dawn when they hunt wallabies and kangaroos. But dingo activity was much lower in the evening where dingoes were baited. Feral cats on the other hand, had higher activity levels in the evening in the baited areas, filling the time gap when dingo activity was low. This suggests they can take advantage of the reduced risk of dingo encounter, to hunt at an ideal time for finding and killing small mammals and nocturnal reptiles such as geckos."
Leila finishes her summary by saying that the "Top End," has suffered terrible declines in small mammals recently. These cats can be an obvious cause if many farmers are busily killing off another predator. The Journal of Applied Ecology published the paper. Thanks to the authors for such an instructive paper.
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