Earth Week: Interlopers In Paradise

Guam EPA Earth Week 2006 - Logo from CJ Santiago of GW High School

I recently read a very good book on invasive species, Out of Eden by Alan Burdick, which begins with a lengthy exploration of Guam’s own infamous ophidian, the brown tree snake. It’s a fascinating book, especially the portion about invasive species in coastal waters around the world.

One thing struck me from the book though; ecologists have realized there is no such thing as a pristine environment. Environments are always changing and dynamic. Species come and go, and while humanity has helped spread many organisms around the world, it is really impossible to untangle the web of life and extricate unpopular species. The brown tree snake is here on Guam; live with it. In the long run birds will return, just not the original birds but new species will develop that can adapt to predatory pressure from the snakes. It might take a million years, but that is a drop in the bucket of evolutionary time scales.

Salon has another interesting story about invasive species, this time in North America. The taming of the American wilderness proved a boon for one cunning canine; coyotes are booming across the entire continent. I mentioned a couple months ago how coyotes are thriving in Chicago. Well they’re doing quite well in New York City too. This is an unprecedented success story, an inadvertent effect of the taming of the American landscape.

In the early nineteenth century the coyote, Canis latrans, roamed the prairies and deserts of the American West, hemmed in by cougars and the wolf packs in the eastern forests. As the old growth forests fell to the axe and plow, the wolves and mountain lions were extirpated and the lowly coyote suddenly found itself the top predator across most of the continent. Coyotes pushed north and east into the farmlands and the Eastern seaboard, getting bigger and smarter all the time.

Today’s coyote is twice the size of his ancestors in 1850 and instead of lone scavengers, they now hunt in packs, colonizing the suburban and urban landscapes of man with aplomb. They’ve learned to negotiate traffic, hunt at night, listen for voices and scavenge from garbage cans. The coyote, like the brown tree snake, has taken an opportunity afforded by mankind and run with it, becoming one of the most successful colonizers of the last century.

Perhaps they are invaders, or maybe they are just filling an ecological niche. Like I said, the environment is ever changing and dynamic, it is only our hubris that demands a static and unchanging nature separate from civilization.