But ... but ... but ... soooo many species are introduced. Some of them were even introduced by humans centuries ago. Or introduced themselves without human interference. How far back do we go in removing introduced/non indigenous species? Are we willing to do without steak, sausage, milk, coffee, tea, and eggs? Are we willing to give up the companionship of dogs and cats?
Europeans brought so many non native species with them like ... horses. But they also introduced donkeys, mules, cows, pigs, sheep, goats, chicken, large dogs, cats, and honey bees, as well as wheat, barley, grapes, coffee, and sugar cane to the Americas. Actually, I'm rather surprised chicken, sheep, goats, and honey bees are introduced species. In reverse, the Europeans introduced the potato, maize/corn, tomato, and tobacco to the rest of the world.
Before the Europeans, the ancient Polynesians brought dogs, pigs, chickens and rats, as well as plants like taro, yam, banana, and breadfruit throughout the Pacific. Again ... bananas surprises me. The Polynesians and the animals they brought with them wiped out about 40 species of birds just in Hawaii. Europeans wiped out another 25 species of birds.
Interestingly enough, the Dingo is an introduced species to Australia. Who knew!?! Granted, they did arrive about 5,000 years ago. Apparently, they came courtesy of ancient seafarers from Asia. Other species introduced to Australia include cattle, sheep, pig, horse, cats, dogs, goat, rabbit, camel, buffalo, banteng, red fox, rats and fleas (of course), house mouse, European honey bee, rainbow trout, mallard duck, spotted dove, European wasp, house sparrow, monarch butterfly, house gecko, the dung beetle, cane toad, myna bird, and red fire ant ... all of which were apparently introduced after the arrival of Europeans in 1788. Whew! That's some list!
In some cases, it isn't just the introduced species that cause the threat to indigenous species ... or are maybe even the greatest threat. How are indigenous species supposed to survive habitat changes by humans so we can raise domesticated animals or plants or build homes. Far easier to blame introduced species (by humans) when the threat IS humans. Surely it can't be the massive banana, coffee, tea, or palm tree plantations. How much land has been made inhospitable to indigenous species so we can eat steak? Do we really need to divert water, dam rivers, or drain wetlands so we can spread out into deserts, onto floodplains, or into swamps or marshes or bogs.