Feral livestock, not feral cats, main cause of small native mammal decline in Top End, Australia

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The native black-footed tree-rat

There is a fascinating write-up of a study about the declining numbers of small native mammal species, weighing up to 5 kg, in an area called Top End in Australia. Top End, as the name implies, is at the top of Australia, dead centre. It is the top half of the Northern Territories, of which the capital is Darwin. It looks like an idyllic place to me. A beautiful landscape and wonderful reserves or national parks, e.g. Kakadu NP.

The native black-footed tree-rat

The native black-footed tree-rat has suffered major declines in the Northern Territories. Photo: Hugh Davies

It is a great place to study wildlife conservation in Australia. To an outsider, it seems to me that the Australian authorities have consistently, across Australia, blamed the feral cat as the number one culprit for the gradual demise of small native Australian species. This is been highly concerning to the authorities. They have devised all manner of means to exterminate the feral cat all of which I would argue are very cruel and ultimately ineffective.

Therefore, it was very pleasing to me to read the write-up of this study on the website, theconversation.com. Without trying to oversimplify matters, because I know this is a complex area, the scientists decided that the main reason why small native mammals have mysteriously vanished across this region is because of a degradation of habitat by feral livestock such as buffaloes, cattle, donkeys and horses. I find that very interesting and surprising.

Top End Australia

Top End Australia. Image in public domain.

One important aspect of this study is that they decided that they have to prioritise by tackling the main causes of the threats to population numbers of the species. They have to do this because budgets are limited; you naturally go to the best method first. They feel that they have achieved a breakthrough. They used 1,500 camera traps and 7,500 animal traps across 300 sites in the national parks, private conservation reserve and indigenous lands of the Top End.

Where the small mammal population was doing well they found good quality habitat and a wide variety of plant species and dense shrubs. Comment: for me this is a recurring story. It is the destruction of the habitat even if it is just grass which has the greatest impact upon the survival of wild species. The habitat is the home of wild animals and when it is degraded there is less food and less shelter for them. They are exposed to predators. Habitat desctruction can nearly always be traced back to human activity of some sort, usually of a commercial nature.

They decided that the negative impacts of feral livestock on native mammals had been underestimated.

Even at relatively low densities, feral livestock are detrimental to small mammals. Through overgrazing and trampling, they degrade habitat and reduce the availability of food and shelter for native mammals.

There are other factors of course such as intense fires which are a very big negative factor. Comment: I expect these fires to become worse in the future due to global warming. This is also a human-made issue. Theoretically or even practically fires can be managed because global warming can be managed.

The research did mention the ubiquitous feral cat of Australia. They argue that the best way to deal with this predator is not to kill them en masse which is the current modus operandi but to manage habitat better with the intention of altering the balance between predator and native mammals to make it more favourable for these prey items.

It suggested that (1) “prescribed burning to protect food and shelter resources” and (2) “culling feral livestock” may be the best way forward to protect native small mammals.

As for dingoes, they suggested that they should be left alone because introducing them in bigger numbers did not reduce feral cat numbers. They preferred the idea of controlling herbivores not the predators.

Above all else habitat needed to be protected. Comment: I just feel a sense of relief that the feral cat is no longer being maligned, denigrated and its killing en masse promoted. As they say, is impractical to try and kill all the feral cats. The authorities don’t even know how many there are or where they are. I hope the authorities digest this research and act on it. I don’t know if this study can be extrapolated to other areas of Australia.