Niles Eldredge - The Darwin Blogs

The Darwin Blogs – January 23, 2007.

Galapagos Blog # 2

January 21, 2007

My Dear Eldredge:

I hasten to reply to your report of January 18, in which you raise some points of interest in regard to my stay in the Galapagos—and also regarding the experiences you and your fellow travelers are now having.

When I recall how cramped were the conditions of my quarters on the Beagle, and how Spartan the nature of our existence on that old, small ship, I am astonished at your description of the luxurious surroundings that you apparently enjoy while making your present visit. That your vessel is somehow connected to the internet is particularly poignant, when I recall the months—nay, even years—required for my letters to reach my father and sisters at home—and for theirs to reach me. You have communication home at the touch of a button!

And your comment on the rain is most arresting. I of course spent my brief time in the Galapagos –in the Fall of 1835, recall—at a time when the climate was quite dry. Only close inspection showed my initial supposition to be wrong—i.e. that the dry brown appearance (downright dead-looking!) of the plants when first I saw them, was revealed on closer inspection not to be utter dormancy as our English plants show in wintertime; rather, they were indeed in leaf, and some even in bloom—but the leaves and flowers were all quite small. Thus I am anxious to hear more about the state of the vegetation now there is rain whilst you make your way about the Islands.

It is not surprising that I failed to observe some of even the more obvious inhabitants of those Islands during my brief stay. After all, I had the opportunity to visit but four of the Islands of this Archipelago. Indeed, I had heard scattered reports about these productions over the ensuing years after my return to England in 1836. I must say, however, that the juxtaposition of penguins with flamingoes, nearly cheek by jowl as it were, as you report, is most surprising testimony to the effects of these various currents about which we knew little so long ago. But I must correct you on one point: I had in fact observed and collected some flamingoes whilst there.

And it is reassuring—though not utterly surprising—to find that the phenomenon of variation—of varieties and species—from island to island has now been found in species other than the mockingbirds and tortoises upon which I remarked in my "Ornithological Notes" whilst still aboard ship; and in the finches studied by Mr. Gould, and in the many different plants studied (after much delay!) by my dear friend Joseph Hooker. One makes generalizations, sometimes, on but a few examples—expecting (I believe you would now say "predicting") other examples to present themselves should the phenomenon prove to be of a general nature.

But, my dear Eldredge, I find in your last report no comment on the actual state of the wildlife of the Galapagos as they now exist. I do hope to hear some comments on these matters when next you write whilst on your journey!

With anticipation of an early reply,

I remain most truly yours,

Ch. Darwin

January 23, 2007

Dear Charles Darwin:

I'm really happy to get your prompt response, which in turn inspires me to reply right away. There's lots of news, for as you know, much can and does routinely happen both on shore and on shipboard in exotic places.

I'll start by picking up the strands of our previous discussions of climate, flora and fauna of the Galapagos. I apologize at the outset: after rereading my previous note to you, I see that I said that modern ornithologists recognize 5 species of mockingbirds in the Galapagos—when in fact the number is actually four: you had the divisions nearly right—but had missed the Hood mockingbird, for the good and sufficient reason that you did not visit that island! Everyone who has looked at these birds agrees that the mockingbirds of Hood Island are more strikingly distinct than any of the others—among other things having a larger, more powerful beak. Once again, the phenomenon (I would call it the "pattern") of inter-island variation is maintained—this time by strengthening the data pertaining to the original example that brought you to the pattern in the first place!

Hood is the oldest of the islands (I have no way of knowing how much you have learned, via the internet, about plate tectonics, "hot spots, and the like). Suffice it to say that new ocean crust is constantly being both generated and swallowed ("subducted" is the technical term for the latter) at margins between adjacent "plates" –which are the major subdivisions of the earth's outer crust. Earthquakes and volcanoes are tell-tale signs of such activities—concentrated as they are along the boundaries between plates. The Galapagos lie just inside the so-called "Nazca" Plate, very near the boundaries of the vast "Pacific" plate and the smaller "Cocos" plate. "Hot spots" are where plumes of deep-seated ("mantle") material are constantly welling upwards to form oceanic volcanoes; as the plates move over a hot spot, volcanoes are gradually shifted away from the source of the lava and become dormant—while new volcanoes spring up over the hot spot. This is how the Hawaiian Island chain has been formed—and is certainly what is happening now in the Galapagos. The enormous volcano forming the island of Fernandina—westernmost of the Galapagos—is the newest, freshest and most violent of this entire cluster of volcanic islands. Hood, far to the southeast (and the first island you spotted when the Beagle arrived in September 1835), is the oldest island still above the waves, though its low, flat aspect plainly shows that it is marked for oblivion.

The Galapagos mockingbird is distributed among most of the islands. The other three are on Hood, Chatham (modern-day San Cristobal) and Charles (nowadays called Floreana—you saw that one as well). The Charles mockingbird is already extinct on the mainland, with remnant populations surviving only on two small islands offshore. Thus there is more to your pattern than you originally expected, as the oldest islands in many cases have the most distinctly diversified elements of the fauna and flora. Not surprising, of course, given the relationship between time, geography and evolution!

Apologies of course are also due to my mistakenly saying that you had not observed flamingoes while in the Galapagos!

The rain has been remarkable in its direct, virtually instantaneous effect on the vegetation. One of our naturalists remarked that our itinerary has taken us to islands where it had been raining before we arrived; or during our visit; or in some cases where the rain has yet to fall this year. So we have seen the entire gamut, ranging from the dry, brown lifeless-seeming vista that met your eye in the Fall of 1835; to situations where small shoots are poking up from the lava fields and sandy soils seemingly as the rain just begins to fall; to entire flanks of volcanoes blanketed in a light yellow green—where the Palo Santo and other trees and bushes have erupted into full leaf and flower, on islands where substantial rain had already fallen before our arrival. Ah water—the very essence of life!

You ask about the current state of the flora and fauna. The Galapagos are strictly protected these days—most of it off limits except to scientists with permits. We on tours must stick closely to the demarcated trails, cannot bring food to most of the islands, and in general must minimize the "footprint" of our visit. Nonetheless the future appears bleak: The Galapagos is the wealthiest part of Ecuador—and the human population continues to expand. The fisheries are severely depleted—and life on land, despite all efforts, remains under severe threat. And we must remember that these islands—even Isabela, the largest of all—are not in any sense huge—meaning that populations are small and vulnerable. I have no idea what has caused the disappearance of the Charles mockingbird on mainland Floreana, but natural fluctuations in climate are often enough to reduce the size of an already-small population below the critical mass from which it cannot recover.

Yet, in general, there is no doubt that it is human agency that has caused the degradation seen on many islands—and the consequent loss of native species on those islands. The most striking example that we have seen so far of the drastic effects humans have had on the wildlife of these islands came yesterday, in our brief visit to James Island (or Santiago). I understand that you had camped on this island for some 15 days—obviously a far longer and much more intense visit than ours. Yet we learned much from our naturalist guide—and through the evidence of our own eyes. When I return home, I intend to post a series of photos documenting the highlights of our trip; I was delighted to capture some good shots of the small Galapagos flycatcher on James—more than friendly, as he saw our small gaggle of sweaty humans as a potential magnet for flies. I was struck by this beautiful little bird because it appears to demonstrate only the first of your Galapagos double pattern: tyrannid flycatchers are restricted to the New World, and the closest relative to this Galapagos species is on the South American mainland (your Galapagos pattern # 1)—but shows no obvious variation from island to island.

But I digress. The availability of fresh water is the magnet that has long drawn human visitors to James. Our visit took us to the area around the old salt works that you visited. (I read in your "Diary" and also in the "Voyage of the Beagle" that you saw a human skull lying in the bushes there. You said the skull belonged to an American ship captain, murdered by his crew. (I can report that people still talk of this—and wonder how reliable that story really was?). But the most striking thing at our landing site was the lighthouse—and a caretaker's cottage left over from the days when the Ecuadorian government placed a lone individual there to make sure no one returned to obtain salt once the works were finally closed.

You will of course recall how sailors in your time routinely took tortoises for food. You yourself consumed tortoises, along with your shipmates—including during your stay on James—and we were told yesterday that you also ate land iguanas while you were camped on James. No need to rub it in, or cause you any undue conscious-stricken guilt, but the fact of the matter is that there are no land iguanas or tortoises to be found any longer on James Island. It is ironic that you may have contributed in some small way to the demise of both land iguanas and tortoises on this particular island.

Yet clearly the main reason for the extinction of these species on James is the introduction of both pigs and goats—put there to serve as handy sources of food for passing ships, especially in view of the dwindling numbers of tortoises. Both are hardy domestic species, quite capable of surviving—thriving, really—on this island, which, with its water, must not seem so very harsh to a pig or a goat. Their numbers exploded. The pigs gorged on tortoise and iguana eggs, and the goats outcompeted the iguanas and tortoises for food. It must not have taken so very long for the native species—the land iguana and the giant tortoise—to succumb on James, victims of competition and predation from these introduced domestic species.

The pigs and goats have since been eradicated—the latter only after GPS technology allowed satellite tracking of "Judas" goats outfitted with transmitters. They would find the company of other goats, and government hunters would then swoop in and shoot all but the Judas goat—who would then lope off to find other friends, and the cycle would repeat itself. That's what it took to eliminate the 20,000 or so goats on the island.

But the effects remain. The vegetation is of course recovering—but in many places remains sparse—the effect of both over-grazing and no doubt the direct impact of human habitation.

The Galapagos are fragile—and remain under pressure—not least from people like ourselves—"ecotourists" who bring economic wealth to the islands (some of which is earmarked for conservationist causes), but also inevitably negatively impact the very ecosystems we have come to witness and hope to see preserved.

I close with some news that helps me link our current voyage with your own on the Beagle those many years ago. A few days ago, news of a death in the family unfortunately forced two of our passengers to leave us and fly home. Later that night, shockingly, one of the crew members (our very personable, popular barman) unexpectedly died in his sleep. He was not an old man. His loss affected us all—but especially his fellow crew members, as he had long been a member of the ship's company's family, liked, admired and respected by all.

These two deaths reminded me of your own experiences at sea. Indeed, if I remember correctly, a seaman fell off the ship and was drowned before the Beagle had even set sail from England! But most of all I remember your pathetic story about "poor Musters"—the youngest boy on shipboard. Along with several other crewman with whom he traveled up the reaches of one of the South American rivers, Musters succumbed to some form or other of tropical fever. You felt touched and deeply saddened—and reflected especially on the fact that that poor young man had just learned about the death of his mother only a few days before he himself died.

Life is fragile—and sometimes cruel. We continue our journey despite this double loss we have suffered, heartened by the sure knowledge that we are privileged to be here—and that one should remain involved as thoroughly as possible in the very act of living each day that we are fortunate enough to still (as you yourself might say) draw breath.

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