Monday, June 25, 2012

Last of His Kind

Shed a tear, if you will for Lonesome George, age unknown but around a hundred, who passed away yesterday in his home in the Galapagos Islands. George was a Pinta Island tortoise (Chelonoidis nigra abingdoni), the last known specimen of his kind. He was found on Pinta Island in 1971, and relocated for his own safety to a pen in a national park. Attempts to mate him with females of closely related subspecies were, not too unsurprisingly, unsuccessful.

Why should you care about George? After all, he was just a turtle, albeit a famous, well-loved, 200-pound turtle. He wasn’t even particularly handsome, even for a turtle. If I can’t convince you that an obscure subspecies of turtle is important, or that George was a living creature, and as such deserves just a smidgen of respect, perhaps you’ll agree that George can stand as a symbol for a lot of last-of-his-kind animals to whom we’ve bade farewell. In 1914, the last passenger pigeon, called Martha, died in the Cincinnati Zoo (not bad enough that she was the last of her kind, but she also had to spend her waning years in Cincinnati). Benjamin, the last thylacine (a marsupial wolf-like creature) died in the Hobart Zoo in Tasmania in 1936. Saddest (to a grouse researcher like me) was Booming Ben, the last-of-his-kind heath hen, who died in Martha’s Vineyard after spending his last four years calling in vain for a mate. His cause of death is officially unknown, but you and I know that he died of a broken heart.

What happened to these animals? Why did they disappear? Some will suggest that they lost in the big game of evolution, that they were unable to adapt and so vanished, and rightly so. Don’t you believe it. In the 1700s and 1800s, passenger pigeons may have been the most numerous animal on earth. During colonial times, heath hens were so common that people looking for work would bargain with prospective employers to have an upper limit on the number of times per week they could be fed the tasty birds. Other now-extinct animals, such as Carolina parakeets and great auks, leave behind similar stories of their prodigious numbers. These animals, and others like them, had existed for tens or hundreds of thousands of years in immense populations.

What happened to them was us. Human interference, beginning with our first ancestors to stumble out of Africa, changed the habitats where these animals spent uncounted eons evolving. Thylacines were hunted out of existence beginning with the first few people who landed in Australia. Heath hens depended on (wait for it…) heaths; as these were converted to cropland and cities, the birds had no place to do their elaborate mating dances. Passenger pigeons may have been doomed by the destruction of a single large forest where the bulk of the population reproduced. George’s Pinta Island tortoises were condemned when feral goats destroyed the native vegetation on his island.

We have hunted, harassed, poisoned, and shot hundreds of species out of existence. We’ve destroyed innumerable acres of habitat, converting it to croplands, or grazing land, or Wal-Mart parking lots. Where we haven’t outright destroyed habitat, we’ve fragmented it into uselessness, or polluted it with pesticides, or introduced pests, parasites, competitors, or predators that don’t belong where we’ve put them. The coup de grace may well be climate change; as the earth warms animals are forced north, or to higher elevations, and there’s only so far up an animal can go, and he can’t take the plants he needs with him.

Again, what do you care? Aren’t we doing just fine without heath hens and ivory-bills? Doesn’t my car run just fine without any help from Steller’s sea cows? What does a golden toad have to do with me? Honestly, the last Chaco azul pupfish probably died without impacting you negatively. But we can’t really be sure. It turns out that the environment is made up of millions of species all linked together in complex webs of interdependence that ecologists are only beginning to understand. Perhaps you could think of the ecosystem as a huge Jenga game, and we’ve pulled out an awful lot of pieces. And there are a lot of pieces just on the verge of being pulled out. A quarter of the world’s birds are considered threatened or endangered. That doesn’t mean that three-quarters are in good shape, either; for many species of birds, nobody has studied whether or not their populations are stable. Reptiles, mammals, and especially amphibians are in similar straits.

So, this evening, drink a toast to George, the last of his kind. But not the last last-of-his-kind that we’ll hear about.

Wednesday, January 11, 2012

In Which a Bridge Becomes an Obvious Metaphor for Impermanence

On the next to last day, we got into the tiny rented Chevrolet Classic and drove from Mendoza, the third-largest city in Argentina, toward the border with Chile. We wanted to see Aconcogua, the tallest mountain in the Western Hemisphere, the tallest mountain outside the Himalayas. There’s a small visitor center near the base, with a short walking trail that provides views of the peak, and a staging area for people who are going to try to climb to the summit. The mountain was beautiful and the half-day we spent wandering around the little park was splendid, but getting there turned out to be more interesting to me.

The road wasn’t bad—a bit narrow and steep in places—but the view was beyond spectacular. The highway follows the Rio Mendoza, a narrow, fast-moving river that arises in the glaciers near Aconcogua and delivers its muddy water down through the Andes to the deserts below. The Andes were pushed up—are being pushed up—by the subduction of the Nazca Plate, which carries the floor of the southern Pacific beneath the South American Plate. The mountains are young and jagged, and unlike any mountains I’d seen before, nearly naked. Look at Pike’s Peak, or any of the Rockies, and the entire base of the mountain is clothed in a swath of conifers that soften the look and obscure the structure. The Andes are different. Aside from a dusting of tiny bushes near the bottom, and a small cap of snow on the highest peaks, the Andes are geology laid bare.

I rode in the back seat of our car and craned my neck to try to see the mountaintops. The sky was clear and sharp and the sun beamed down. We stopped every so often to take pictures. The air smelled of creosote bush and other desert plants. All of us were biologists who had worked in the North American deserts, and we struggled to match the unfamiliar plants to those we knew from home; some were cactuses and mesquites, but others were completely new to us.

At each stop, I was impressed by how unrelentingly huge and empty the mountains were. There was almost no animal life, and the plants were sparse and small. It vaguely reminded me of the Sierra Madre Occidental in Mexico, except that the mountains were twice as tall. The strata of the rocks were plainly visible, all the way up the mountains, but they weren’t even or laminar. Instead, the layers were twisted and bent by the pushing-up of the mountains; in places it was clear that giant columns of rock had even been inverted in a manner that spoke of incredible violence, but violence that had taken tens of millions of years to accomplish. That was the message of the Andes—time, time, and more time.

The stunted shrubs around the bases of the mountains were probably three or four times older than me. They grow slow, and live long. I stood beside the road and looked up at hundreds (thousands?) of layers of rock, each one of which represented thousands (tens of thousands?) of years of sediment drifting to the ocean bottom. It was on the other flank of the Andes that Darwin found the rocks that supported his friend Lyell’s ideas on the age of the earth, but that’s not what made Darwin a genius. You’d have to be blind or stupid to ride through the Andes and not understand that the earth is an old, old place.

After our day on Aconcogua, we rolled back down Ruta 7 toward Mendoza, alongside the river again. In places, the river had dug deep canyons in solid rock, leaving cliffs a hundred or more feet high. How many eons does that take? Between the road and the mountainside, an abandoned narrow-gauge railroad rusts into ruin, disappearing at places underneath talus rockslides. A steel bridge is covered by rocks, looking as if it has partially melted into the mountain. “The mountain is taking it back,” one of my companions said, and I agreed with her. The earth takes it all back.