Lessons of the Galapagos
The Galapagos Islands, unique because they were formed by volcanic eruptions in the middle of thePacific Ocean where two tectonic plates interact along a restive “seam,” periodically erupted over millions of years. The plates, slowly moving along the seam, generate cones formed by eruptions separated by several thousands or millions of years. Although several islands are separated by a few miles most are many miles apart. Some islands are marred by recent volcanic lava flows which obliterated emerging life forms in their paths. Most landscapes are harsh and seemingly unsupportive of terrestrial and avian life. One wonders where a bird or lizard might find a simple drink of water.
The youngest cone-islands support little life; maybe a few cacti and a shrub or two. Others feature actual ecosystems, although often sparse ones. In contrast, Santa Cruz Island, containing uplands which actually trap significant rainfall, has mature soils supporting robust agriculture and fruit trees. Dense tree stands on Santa Cruz remind one of Midwestern U.S. deciduous forests.
Each island is different, distinct in that it was never part of another island. Most importantly, none of these islands were ever part of a continent.
Seabirds, trading freely among the islands, are the same species no matter where they are found, although some limit their haunts to only one or two islands. The penguins, flightless cormorants and marine iguanas, similarly cosmopolitan, are found to be the same creatures among the islands.
The finches and mockingbirds, on the other hand, colonized individual islands, thence to adapt to the unique conditions of each. This adaptation, of course, is what makes the Galapagos Islands uniquely valuable among students of evolution and biology.
If the Galapagos Islands had been part of South America at one time before breaking away, they would be populated with creatures which were part of the South American biological community prior to separation. But they were not. They emerged in the Pacific long after the Pangaean continental fragments had found their present homes on the planet.
The Galapagos Islands were colonized by a few species which found their way to the islands on driftwood or mats of floating debris, or swam there, or were blown off course during migrations. The finches arrived to find ecosystems barren of grosbeaks, woodpeckers, sparrows, warblers, tanagers, wrens and thrushes, so the finches gradually differentiated over time to fill the niches occupied by those species on the continents.
An Asian ornithologist would substitute laughing-thrushes, bulbuls, babblers, drongos and starlings for the absent niche-occupants.
The finches, challenged by desert conditions on some islands, turned to vampirism for survival. [Oh golly, say readers, this isn’t the Disney Channel any more. Yes, you have that right.] We watched a half-hour video on finches on board our vessel which came close to turning my stomach.
Mockingbirds evolved into different habitat-specific forms as well. And we were warned that the mockingbirds on one island had learned to recognize water bottles and pierce them for water. New evolutionary adaptation?
The short-eared owl, light colored in the American West, has developed dark plumage to hide in the dark volcanic formations in the Galapagos, there to prey relentlessly upon seabird nests. It’s an easy living.
Lava makes an interesting substitute for coral under the sea, providing plentiful hollows and hidey-holes for eels, anemones, urchins and a spectacular array of colorful fish. The snorkeling was a new mind-blower for me, and also for my expensive allegedly waterproof camera, which is now a chromed paperweight.
A mystery I have not had time to investigate is this; how in the world did the giant Galapagos tortoises get to Santa Cruz Island? We saw sea turtles all over, mostly in the sea but occasionally hauling out to dig a nest in the sand. They do not much resemble the tortoises. Perhaps readers will enlighten us.
On the bleak lava islands the sea lions and seabirds bring their lunches harvested from the salt water onto shore, there to share the leavings with the crabs, finches, mockingbirds and the ever-present raiding frigatebirds. The harvest from the sea sustains a whole community
Unless one is a scuba fanatic, one trip to the Galapagos Islands is probably sufficient. But the one trip must be a high priority on your bucket list. Actually, since I forgot why someone coined the phrase “bucket list”, let’s just say that a Galapagos cruise needs to be on your absolute To Do list, soon.
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