Dingoes May Not Be the Answer to Australia’s Cat Problem
Diet of dingoes and cats in Central Australia: does trophic competition underpin a rare mammal refuge? (2018) McDonald et al., Journal of Mammalogy, DOI:10.1093/jmammal/gyy083
Feral cats are a huge problem for wildlife in plenty of continents. However, there’s nowhere they have had quite so severe an effect as in Australia. Mammals between 50g and five kilos have seen huge reductions in numbers, and many species have gone extinct. Yet there are some areas in Australia which appear to present refuges for native mammals, so it’s crucial to understand the mechanisms behind these areas.
The MacDonnell Ranges in South Australia are home to large dingo populations, which prey on the local kangaroo species. Dingoes can also suppress cat populations through direct predation. The purpose of this paper was to investigate to what degree dingo and cat diets overlap, to see whether the presence of dingoes contributes to the formation of a refugee for native mammals.
What They Did
The MacDonnell Ranges is a rugged mountainous area which supports several species that are no longer present elsewhere in Australia. Scats from both species were collected throughout the Ranges, and then examined for contents. The researchers were able to break the diets of both dingoes and cats down into mammals, birds, arthropods, reptiles or frogs, vegetation, or rubbish, with mammals further classified into small (less than 500g), medium (500g – 7kg), or large (more than 7kg). The researchers than analysed dietary overlap between dogs and cats.
Did You Know: Exploitation vs. Interference
Competition can take many forms, and in this experiment two of those forms were considered likely. Exploitation competition occurs when one species consumes the resources that another species also needs, so there doesn’t necessarily need to be interaction between the two species. Interference competition occurs when one species directly changes the behaviour of the other species. In this situation, that would include the predation of dingoes on cats, forcing cats to avoid certain areas.
What They Found
The diets of dingoes and cats appeared to be quite distinct, with dingoes mainly consuming large to medium mammals and cats going more for small mammals, birds and insects. There was some predation of cats by dingoes, but all in all the results here seem to indicate that it’s not dingoes that are stopping cats from wiping out smaller to medium sized marsupials.
The point of the paper was to see whether or not exploitation competition starts to become a factor when resources are scarce. The impression that the paper gives is that dingoes don’t have too much trouble acquiring prey in the area, and the results don’t seem to give a strong indication of changes in prey species with resource fluctuation.
Dingoes don’t seem to need to go after the prey that cats rely on in this part of Australia. Additionally, cat diets don’t seem to shift much here either from their normal preferences. So ecologists in this part of the world will have to investigate further to understand why areas like this provide a refuge for native mammals species. The authors suggest that it is simply habitat complexity which is reducing the efficiency of the cats hunting behaviour. Either way, this paper is a good reminder that even if scientists don’t get what they want when they carry out a project, the findings are still important.