Ever since that time long, long ago when humans first set off in flimsy boats to explore the Seven Seas, island species have been at risk. Many of these animals, insects, and plants evolved over millions of years, perfectly adapting to the environment in which they lived—an environment without competition from terrestrial predators or trampling herbivores. Some birds, like the well-known species on the Galápagos, never needed to develop flight-or-fight behaviors, never learned to fear.
And so, from the start, seafaring humans—whether they stayed and colonized an island, or merely paused in passing to stock up on water and food during long sea journeys—found island birds easy prey. The flightless dodo was eaten to extinction; the flightless kakapo nearly was.
Settlers brought their livestock with them, mainly goats and pigs. Rabbits were introduced to provide food and quickly multiplied. Stoats, imported to hunt the rabbits when their populations got out of hand, found island fauna easy prey. Cats initially provided pest control services when rats disembarked from visiting ships but soon, adapting to a feral lifestyle, began to hunt the unsuspecting birds. Many alien species of plants were introduced, some of which adapted quickly to the new conditions and spread. The native animals and plants simply could not cope with such unexpected invasions. The delicate balance of nature was interrupted, again and again, with disastrous results. Countless island species disappeared along with the dodo; countless others were brought to the brink of extinction.
While doing the research for this book, I met and spoke to some extraordinary and dedicated people who have been fighting to turn back the clock on these islands. I have been learning about the Herculean efforts required of them as they struggle to save unique and very precious life-forms, both animal and plant, from extinction. It cannot be done without hard work, absolute commitment, and a willingness to face hardship and sometimes danger. And one of the most difficult, challenging—and often controversial—aspects of their work is, of course, the task of removing alien species from island habitats.
In other words, these biologists have been forced over the years, and around the world, to poison, trap, or shoot thousands and thousands of innocent creatures. They must not relax. The work is intensive, and usually very expensive. The same techniques cannot be used on all. The larger ones, like goats and pigs, can be hunted. Cats can be shot initially, but as their numbers are reduced they have to be trapped. Rats are even more difficult, mainly because of their sheer numbers—only poisoning has so far been effective. And there is always the possibility, with both trapping and poisoning, that the wrong animals will be killed, especially native rodents. On one island in the Pacific, the bait was taken by land crabs—it did not harm them, but hundreds of rats escaped. On Canna Island in the Hebrides, biologists evacuated 150 endangered canna mice (a distinct subspecies) before successfully exterminating the approximately ten thousand brown rats that had invaded this small island. (The mice will soon be reintroduced.)
It is not surprising that the large-scale eradication of so many luckless creatures has led to opposition from many of those concerned for animal rights. They argue, with justification, that the welfare of the “pest” animals is not adequately addressed. The biologists are accused of cruelty and indifference to the suffering of living beings who also have a right to exist. After all, none of them chose to invade the islands where, when given free range, they set about living off the land. Unfortunately, this was very destructive. Goats are particularly skilled in this respect. They are intelligent and adaptive. They need little water and can eat almost anything. When they have finished off all the ground foliage, they even climb trees. Rabbits, while smaller in size, are far superior in their ability to multiply. And think how even a well-fed domestic cat can inflict severe damage on local bird and rodent populations. On an island, the impact of feral cats can be devastating.
My friend Don Merton, who has been involved with restoring islands for decades, told me how, in the late nineteenth century, the lighthouse keeper’s cat on Stephen’s Island, New Zealand, killed all eighteen of the last Stephen’s Island wrens known to science, and laid them at its owner’s doorstep. This wren was just one of the countless endemic species exterminated by animals unwittingly taken to islands by humans.
But, let me repeat, none of the introduced species went voluntarily to the islands. They had no more choice than the early cargoes of prisoners off-loaded at Botany Bay. We put them there. Just as we put mongooses in the Virgin Islands to kill snakes. We put arctic foxes on the Aleutian Islands where, safe from their predators, they could breed and provide skins for the fur trade—while at the same time decimating some of the island fauna and damaging the whole ecosystem. We took European red foxes to Australia so that people could hunt them with horses and hounds—and the foxes hunted the smaller indigenous marsupials and birds. The only crime of these so-called pest species is that they have been—just like Homo sapiens—too successful.
It comes down to a conflict between concern for the individual and concern for the future of a species. Even the needs of individuals within the population being saved are sometimes subsumed for the good of the species. Animals raised in captivity may be released into the wild in the certain knowledge that 30 percent or more will not make it. I have always been an advocate for the individual. But after learning how some of the efforts to save the very last members of an amazing and unique species—such as the kakapo or the Zino’s petrel—almost failed because of cat predation, and looked at the utter destruction caused by goats and rabbits, I had to rethink my position.
If only there were really humane ways of removing the alien species. But sterilization, as sometimes practiced with stray dogs and cats, simply wouldn’t work, and even if you could live-trap all the predators—where would you put them? What could you do with shiploads of pigs and goats that had been corralled? If only the unfortunate invaders had never been introduced, if only there was an ethical way of removing them. But they were, and there isn’t—and they have to go. After all, as Don said to me, alien predatory animals in order to survive must kill hundreds if not thousands of native birds and other wildlife each year—so causing suffering that is unseen and ongoing.
And even though I grieve for the slaughter of the invaders, I am filled with admiration for the persistence of those who work so hard to remove them from the islands. Don Merton, who first succeeded in eradicating rats from islands in the early 1960s, was a true pioneer in techniques for removing alien species. He developed methods for removing invasive species that have been modified for eradication projects around the world. No one wants to devote themselves to killing—yet as we have seen, to protect the birds and their defenseless young it must be done.
All of these island birds exist only because of the determination and ingenuity of those who refused to let them die. I have attempted to do justice to the extraordinary men and women who have saved these island birds from joining the dodo in the void from which there is no return. They have endured many setbacks. They must be patient, persistent, and resilient, as well as tough and courageous—and possibly a little crazy. And as you will see, they are.