"It is our decision, ours today, whether Earth continues to be a marvelously living, diverse oasis in the blackness of space, or whether the 'charismatic megafauna' of the future will consist of Norway rats and cockroaches."
- Dave Foreman, Confessions of an Eco-Warrior
In the first chapter of his book Sailing with Noah, Saint Louis Zoo President Jeffrey Bonner stands outside of his office, watching drama unfolding at his bird feeder. House sparrows, starlings, and rock doves (pigeons) bickered and squabbled, with one unfortunate sparrow getting the worst end of the deal. Bonner was mulling his options, deciding whether or not to intervene. However, "before I could move, I had a... thought. Not a single one of those birds were supposed to be there in the first place. All three species - house sparrows, starlings, and pigeons - are interlopers."
If the brown tree snake's spread across the islands of the Pacific could be likened to a blitzkreig raid, then the pigeon, starling, and sparrow would be more like a march of world domination. From their native lands they have now spread across the globe in the wake of human activity... and they haven't traveled alone. Besides our domestic animals (many of which have gone feral in new lands), a host of other animals have followed humans across the world and established themselves around the globe.
If European birds have invaded North America, then at least the North Americans can take comfort in knowing that gray squirrels and Canada geese have invaded Europe. Brown rats, cane toads, raccoons... these animals belong to a select group of species which I call the "wildlife weeds."
Weed wildlife, like weed plants, are tough, adaptable, and tend to be generalists. Some are invasive to the areas where they are found now, some have been native, but have changed their behavior dramatically. They breed readily and thrive in a variety of habitats. Most importantly, they do not seem troubled by the presence of humans, and many have adapted to take advantage of humans as a provider of habitat and food. As a result, they tend to out-compete more sensitive species, eventually supplanting them.
There's a beautiful creek in the park near by home, one where I go bird-watching on my days off. Incredibly, despite its seeming perfection for waterfowl, I almost always see only two species - Canada geese and mallards. On the rare occasions when I do see something else, the bird in question usually takes off in a panic as soon as it notices me, even if I'm far away. Mallards and geese are comfortable around people - they don't waste energy flying away from me, and some even approach me looking for food (doubtlessly spoiled by picnickers elsewhere in the park). For many island birds, a lack of fear of man proved disastrous to their survival. For many weed species, lack of fear of man (or at least general indifference) is a winning strategy.
I'm afraid that we may be moving towards a world where most species are either extinct or found only in the last remnants of wild habitat away from humans. Instead, the world will be filled with a cadre of weed species, which will be the same all over the planet. It won't matter if you are in New York, Nairobi, or New Delhi, the animals in the park, the birds in the trees, will all be the same.
We'll have created new, blended, simplified ecosystems, far less unique and magical than the ones that used to exist. And the world will be a much drabber, sadder place.