Have some vets give em a shot.

Beyond the cost to capture 14,000 horses, the stress alone is cruel and potentially lethal in itself.

Requiring capture and chemical euthanasia would guarantee not nearly enough horses are removed to protect the ecosystem, which is then cruel to the native Australian species they're pushing to extinction.

A bullet is quick enough.

"a threat to local ecological systems due to their grazing and trampling of the ground and native plant species," What do you think your sheep are doing?

Sounds like the machinations of big cattle ranchers in the American west who promote the same lies.

I've posted articles on the subject a number of times previously.

I even acknowledged that in my OP, thinking of you and those previous interactions.

This is Australia. These horses are utterly alien to these ecosystems, and are now encroaching on protected areas that have been kept free of sheep and cattle.

There is absolutely no reason to protect these horses other than an appeal to emotion. Tell me one ecological reason to keep these horses in an ecosystem that has never seen hooved placental mammals before.

as wild horse populations in the western U.S. The two should not be conflated.

in a somewhat 'academic' sense. The horse species that resided here died out 10-12 thousand years ago - along with the disappearance of most other mega-fauna. The modern horse is clearly a reintroduction - and not quite the same species as those that came before. The argument that anything that was here between 10-15 thousand years ago would have to also allow for giant varieties of bears, sloths, wolves, mammoths and sabertooth cats (among others). And, just to be argumentative - would also have to advocate the removal of most variety of domestic animals, with strong emphasis on all dogs (virtually all European) and every breed of domestic cat - and to get down to the real nitty gritty, homo sapiens, (by far the most 'invasive' and ecologically destructive interloper of the bunch).

We obviously are not going back to 'the way things were' (short of another extinction event - in which case it will no longer be our problem to solve) - so (to my mind) that means we are stuck with our feeble, and sometimes shortsighted and errant, efforts at management. To that end - while nobody is a particular fan of 'culling' events - one has to concede that they are generally the better alternative over ecological devastation, starvation and disease.