Galapagos Conservation Trust,
18 Curzon Street, London, WIY 7AD
Tel: 0171-629 5049 Fax: 0171-629 4149
Presented at the BCG Symposium at the University of Bristol, 19 April 1997
The Galapagos Islands - land of the tortoise, for that is how the archipelago was named "Galapago", the old Spanish name for "saddleback" served as reference to the saddle-like shape of the carapace of the giant tortoises that were found in these distant islands.
The galapagoes first met man in 1535 when the Bishop of Panama stumbled upon the islands located 600 miles west of Ecuador, in the eastern Pacific Ocean I first met the galapagoes in 1983, my first attempts at communing with these placid chelonians ending in havoc as my tent collapsed upon me in the middle of the night, accompanied by a sharp, alien hiss and the sound of a heavy object making contact with my nose Welcome to tortoise-ville!p Galapagoes paradise!p I was in the most wonderful place, camped on the rim of a volcano called Alcedo on the largest island, Isabela The inner slopes gave onto a flat caldera several miles wide with evidence of recent volcanic activity in the form of dark tongues of lava spread across the caldera floor.
A fumarole smoked silently about a mile away The rim resembled a strange golfcourse with carefully trimmed greens interspersed by small shrubs and ferns overhanging 'bunkers' Some of these 'bunkers' were full of water which had dripped off the lichens and mosses which hung off the trees and shrubs Dotted here and there, some on their own, others huddled together these giant reptiles enjoyed a peaceful existence.
On a short trip around the rim, I had earlier counted some 200 tortoises Most were adult, one or two truly gigantic creatures In this wilderness, I believed I could have travelled back in time some thousands of years and the scene would have been little different Alas, that world is no more.
Anyway, back to the first encounter Tortoises have poor eye-sight and one had discovered the opening of a tent flap bang in the middle of his traditional path He'd entered, had a nibble at the green canvas, and then proceeded to try to walk through this minor impediment - (that's the way galapagoes usually negotiate minor obstacles) He awoke me; I tried to look out of the tent and my nose met his shell Tortoise meets Man.
The galapagoes have occurred with uncanny regularity amongst the historical literature recalling expeditions to far away places; and usually for two reasons .... their size and their taste, or perhaps I should say their 'edibility'.
Ambrose Cowley, in 1684, wrote about these islands "Here being great plenty of provisions as Fish, Sea and Land Tortoises, some of which weighed at least 200 pound weight, which are excellent good Food".
William Dampier was on the same ship as Cowley, ( incidentally only the second British vessel to visit Tahiti after its discovery, 5 years earlier by James Cook) He wrote "I do believe there is no place in the world that is so plentifully stored with these animals..so numerous that flve or six hundred men might subsist on them alone for several months, without any other sort of provision They are extraordinary large and fat and so sweet, that no pullet eats more pleasantly "
What enormous luck for those early sailors Not only were they edible, they were also big.
Sailors commented on their size at every opportunity Woodes Rogers, in 1708 wrote that "Some of the largest land- turtles are about 300 pounds weight. (Some tortoises have since been weighed at 450 lbs plus! - that's over 200 kilos for Europeans) Rogers didn't like the look of them, that's for sure, painting a picture of monstrous appearance "The creatures are the ugliest in nature, the shell not unlike the top of an old hackney coach, as black as jet, and so is the outside skin, but shrivelled and very rough The legs and necks are very long, and about the bigness of a man's wrist; and they have clubfeet, as big as one's flst, shaped much like those of an elephant with 5 thick nails on the fore-foot and but four behind, and the head little, and visage small like snakes, and look very old and bleak Two of the men were mounted on the back of one of them which, with its usual slow pace, carried them and never regarded the weight"
Rogers was puzzled though "It is strange how the latter (giant tortoises) got here, because they cannot come of themselves and none of that sort are found on the main, " His answer would come some 130 years later and, though he wouldn't have been around to meet the father of evolution, it is likely that some of the tortoises did - those that weren't eaten!
Though their longevity is a source of wonder, and perhaps jealousy, mankind has had a good go at preventing them from reaching old age.
The tortoises provided a food stop for buccaneers and passing sailors during the 17th and 18th centuries It is likely that many hundreds, if not thousands, were taken during this time for food, but word got round of another useful quality for these harmless creatures Tortoises proved to be an ideal source of shipboard provender in those early days of no refrigeration, living for months without food or water and providing fresh meat and fat which was widely praised Townsend reports that after keeping the animals on deck for a few days whilst they "emptied their bowels", "the animals were frequently stored below decks like so many casks, being brought up for slaughter" Some were known to have survived storage upside down, stacked one upon the other, for up to a year with no perceptible loss of edible quality.
During the 18th and 19th centuries whaling vessels regularly used the Galapagos Islands as a hunting ground and a site to stock up on tortoise meat The tortoises were exploited as a food source, for their meat and oil It is difficult to assess the scale of 3 centuries of plunder, but the total number of animals removed from the islands must have exceeded 100,000 Even more devastating were the introductions of goats and pigs to act as a supplementary food source when the tortoises ran out!
Captain Porter in 1813 stated that "no animal can possibly afford a more wholesome, luscious and delicate food than they do; the finest green turtle is no more to be compared to them in point of excellence than the coarsest beef is to the finest veal " 22 years later, Charles Darwin was not so enamored by their taste In fact, by Darwin's time consumption had declined.
Since tortoises were now largely restricted to the inland and highland regions, they were harder to find and carry back to the ships Large tortoises were checked for their fattiness As Darwin wrote - "When a tortoise is caught, the man makes a slit in the skin near its tail, so as to see inside its body, whether the fat under the dorsal plate is thick If it is not the animal is liberated and it is said to recover from this strange operation "
It saddens me to realise that man's relationship with the galapagoes for 300 years, from their discovery until Charles Darwin's arrival, focused almost exclusively on exploitation Though certain individuals must have wondered, even questioned the existence of such giant reptiles on such an isolated archipelago, it took the unique blend of qualities in one man at the right time and place to begin to put answers to the whys and hows and wherefores of the species.
It is likely that over the passage of hundreds of thousands of years, a raft of vegetation washed out from the Guayas River on the west coast of Ecuador during the rainy season and drifted over to the Galapagos archipelago with pregnant tortoises on board Remote though this possibility is, it is the likeliest theory for the arrival of tortoises in the Galapagos Even more incredulous though, is the ability those odd arrivals had to survive and reproduce in the hostile terrain of these volcanic islands.
Every few years, a climatic upheaval occurs in the southern hemisphere known as 'El Nino' A movement of the intertropical convergence zone (ITCZ) creates warm waters in the eastern equatorial Pacific producing a lot of rain So much rain, that streams and rivers and even waterfalls are created in Galapagos where none would have occurred during the previous one or two hundred years It's probable that the odd tortoise would have been washed out to sea in these deluges.
Now tortoises can swim, of a fashion enough to keep them afloat until they reached an island in the archipelago down current from their home island In 1924 William Beebe recorded how a giant tortoise was thrown overboard from their ship the Noma, in order to observe its fate. "Not only did it float upright with no attempt at balancing, but considerable of the anterior part of the shell was exposed, making it possible for the head to be lowered under water, held easily clear of the surface or raised high above it But the most surprising thing was the ease and excellence of its swimming ability The Reptile would swim toward the rowboat which / occupied, and flnding it too high would turn and swim over to the Noma, stretching its head high along the waterline Then it steered its way to the companionway This was with, across, and against the very appreciable current at will. I could see the throatvibrate in breathing, without any detectable lowering or elevation of the body So for a time at least these creatures have perfect control over themselves in the water-".
Darwin's keen observations are recorded in other learned books, and useful material evidence these creatures were to his nascent theories and proposals on natural selection as the powerhouse of evolutionary change.
I do not wish to delve into taxonomic mine-fields; simply acknowledge that 15 separate sub-species have been recorded from the archipelago.
Ten of these sub-species were found on different islands and another five occurring on different volcanoes of the largest island Isabela.
The developing relationship between man and galapagoes hasn't benefited the galapagoes at all Of the 15 sub-species, 4 are extinct Quite possibly, the last individual of the Fernandina island sub-species was removed as a specimen by the Californian Academy of Science in 1905 Whenever I've visited Fernandina, I have felt there was something missing from the fauna complement.
The Pinta island subspecies is virtually extinct, there being only one old male tortoise known as Lonesome George I'm not sure if there is a word which could aptly describe the state of this subspecies Lonesome George is kept at the Charles Darwin Research Station (CDRS) where much of the work has been done to entice George to reproduce Sadly no man, woman or tortoise can quite match the foreplay of the female galapagoes of Pinta island, and he is destined to die with his kind Of the remaining ten subspecies, perhaps 13-15,000 survive, some 5% of the estimated original population.
Exploitation continued into the 20th century as settlement of the islands developed in earnest Salt-mine workers collected tortoises on James Island in the late 1920's; ranch hands eliminated tortoises from the lower south-western slopes of Cerro Azul volcano on Isabela Island, and as late as 1959 convicts from a penal colony in southern Isabela were exploiting tortoises on Sierra Negra volcano for their oil.
1959 was notable in the history of man's relationship with the galapagoes for it was in that year that the Galapagos National Park was formed, covering 97&#deg; of the land area of the islands and virtually all the tortoise habitats.
In 1960, Robert Bowman edited a collection of contributions to science from Galapagos studies In the chapter on tortoises, the following statement is to be found.
"Unless strong action is taken to reverse present trends, the 300-year history of human contact with the galapagos tortoises seems certain to end with the extinction of the species, probably in this century Despite improved protective laws and increased enforcement by the Government of Ecuador, the species last chance for survival probably revolves about the recently established Charles Darwin Research Station (CDRS) on Indefatigable Island. Principally from this station must come the research which can hopefully result in the management of the remnant populations so that they can survive and increase".
In the first Charles Darwin Foundation publication Noticias de Galapagos, a status report was published Being of international repute, scientists from around the world were involved in the initial research work (as indeed they still are today) This is reflected in the items in Noticias at that time.
"Espaces menac6es directement par I'homme - Les Tortues Terrestres des Galapagos"
It seems as though they are totally extinct on Hood, San Cristobal and Floreana A few individuals survive in the craters of Duncan and Marchena islands "The report goes on to reprimand local fishermen for the continued slaughter of tortoises around the coasts - ironically most galapagoes found in coastal regions were female, migrating down to nest on the lower slopes of the volcanoes As a result of the coastal collections, the sex ratio of many subspecies became skewed against females, i.e. males outnumber females, hampering natural reproduction chances even further.
The 1960's were characterised by the first detailed surveys of surviving populations The task of saving what was left began in earnest during these years The best success story involved the Hood Island tortoise or Espaniola tortoise - a small saddle-back variety Successive expeditions to search for galapagoes managed to collect 13 individuals Four more were donated to the CDRS from the mainland where they had been kept as pets Of the 17, 15 were female and the two males were exasperatingly reluctant to get down to the business of saving their race Eventually, a 'handsome' (my interpretation) stud from San Diego Zoo in California was added to the group, and "hey presto", nature took its course, and before too long the Station's investment in the captive breeding programme was producing dividends.
The galapagoes nest building behaviour is fascinating.
Digging the nest hole is an elaborate task and may take more than one or two days to finish The tortoise works blind, rotating and using each hind leg in turn until a neat cavity about 18" deep is made behind her Whilst digging the female urinates frequently to soften and bind the loosened soil The eggs are dropped in a matter of minutes - usually a clutch holds about I0 eggs laid in 2 or 3 layers with about an inch of soil between layers.
The hole is filled and then the female moulds and presses the moistened earth over the completed nest, repeatedly dropping the plastron suddenly on it and sliding about over the area to compact the top layers into a firm mass The female then departs The baking sun then heats the surface soil causing it to rise, much like the pastry of a pie, and the space below this crust develops its own humidity and temperature regime ideal for egg incubation For the next 4 - 8 months, the eggs are incubated by the sun, during which time the temperature in the centre of the clutch may vary between 24° and 32° centigrade.
The exact temperature at a certain stage in the development of the embryo is crucial in determining the sex of the eventual hatchling.
This elaborate process has been researched by scientists at the CDRS and attempts to artificially replicate the process established with the help of Park Service personnel Using the best Heath Robinson techniques a hair-dryer has been found to be the most reliable piece of equipment for maintaining the correct temperature and humidity regimes necessary for the incubation of these invaluable eggs.
Between 1970 and 1976, 79 young tortoises were hatched, reared and released, no mean feat considering the basic resources available to Station and Park Service staff at the time Those tortoises that were repatriated in the early 1970's are now 25 years old Attempted mating has been observed though no nesting has been recorded The adults back at the Station are still producing offspring which are regularly returned, or repatriated to their native island Who knows when the first visitor on the Hood Island visitor site at Punta Suarez will be able to marvel at the sight of a big chelonian standing next to a big Waved Albatross in the wild Indeed that will be a historic moment for us all to savour.
Direct human slaughter of galapagoes has all but been extinguished Today, a more insidious legacy of man's presence in these islands has taken over the mantle of grim chelonid reaper The most devastating effects of all have been caused by the introduction of non-native mammals Pigs dig up and destroy the eggs and kill young animals up to 10 - 15 years of age (particularly on James Island where pigs have also been observed feeding on eggs being laid by the green turtle literally as they were being laid into the nest hole on Espumilia Beach) Dogs also dig up eggs and kill young under I0 years of age (Southern Isabela, Santa Cruz and San Cristobal islands suffer in this respect) Black rats kill and eat the newly-hatched young (This is a major threat on relatively dry islands like Duncan, almost halting reproduction in its tracks) Donkeys trample tortoise-nesting areas, crushing eggs and changing forested areas into open, grassy pampas creating dust-bowl conditions However, the greatest villain I have kept till last - the goat!
Goats are direct food competitors, "grazers par excellence" On small arid islands they can eat everything, as they have done on Hood and Pinta islands They have been eliminated from Hood Island, enabling the tortoise repatriation to go ahead successfully as I have already mentioned On Pinta, the home of Lonesome George, the Park Service informed the CDRS that goats had been eliminated around 1990 However, they had misjudged and now the goats are back Pinta is 2 to 3 miles wide with a rugged highland area full of nooks and crannies where goats can hide It only took I pregnant goat to hide whilst the search party were surveying the island, for the population to resurrect itself And once again, Lonesome George's island is goat-ridden.
The wonderful world on top of Alcedo volcano - verdant lush vegetation festooned with lichens, mosses and orchids, "Galapagos Eden", has changed drastically Goats had always been running wild in southern Isabela, but the northern part of the island where Alcedo volcano is found, is separated from the southern part by a thin isthmus of lava so rugged and impenetrable that it was thought to provide a most effective barrier to animal migration However, goats got across sometime during the 1980's, possibly along the coast, drinking sea-water to survive Once across, the population established themselves in low numbers until the early 1990's, when scientists and park wardens, naturalist guides and visitors began noticing their presence In the humid highlands of Alcedo, the goats found their Eden The population estimates rose alarmingly and exponentially to the point where an estimated 100,000 goats have been recorded as laying waste the northern part of Isabela island, containing the last 3 tortoise subspecies with notable populations By their presence goats actively compete with the tortoises for food.
They also destroy any canopy vegetation, depriving the galapagoes of shade from the equatorial sun The drier conditions create further problems such as soil erosion and dustbowling It's a worthy reminder to say that goats alter the fragile habitats of these islands, causing extinction of more than just chelonians.
Back on Santa Cruz island, Station and Park Service personnel continue to improve their ability to captive-rear giant tortoises Over the years it has been refined to a state of the art level Using the resources available, tortoise reproduction is maintained at maximum output - the young hatchlings kept until they are old enough to fight off attacks by predators such as cats, rats and dogs which may still remain uneliminated from their native island And, of course, the galapagoes in their enclosures at the Station act as mascots of their kind, allowing visitors a better chance to see them, learn about them and the work of the Station and Park.
Occasionally, they receive postcards from afar There is for example, Harriet at the Queensland Reptile and Fauna Park in Australia Only a couple of years ago did her history come to light She's an attractive old girl and here's her age... Chronology in reverse order thanks to the research work of Scott Thompson, Stephen and Terri Irwin.
|1987||Harriet moves to the Queensland Reptile Park|
|1952||Harriet moves to Fleay's Fauna Sanctuary, Australia.|
|1929||Tom (Harriet's chelonid companion) dies.|
|1870||Earliest written account of Harriet in Australia. (She's obviously a centenarian)|
|1860(circa)||Probably placed in the Brisbane Botanical Gardens by John Wickham, First Government Resident of Moreton Bay, Australia.|
|1841||John Wickham retires from the Royal Navy having been captain of HMS Beagle following Fitzroy. Wickham moves to Australia bringing 3 tortoises with him.|
|1836||41 During this time, Wickham was First Lieutenant on HMS Beagle and, following the expedition, is given a present of 3 young tortoises by the naturalist on board the vessel.|
|1835||The naturalist collects Harriet from James Island as he visits the islands in September of that year.|
|1830-32||Harriet hatches on James Island, unaware of what lies in store for her.|
This makes Harriet 165 years young!
The longevity of galapagoes is legend and, from this story alone, I can begin to believe that the tortoise that crashed into my tent all those years ago may well have seen HMS Beagle under sail in Galapagos waters.
During the last 2 or 3 years, the relationship between man and the giant tortoises of Galapagos has been punctuated by threats, discoveries and acts of conservation Fires, poaching, disease and the activities of the hordes of goats and one or two petty politicians have threatened the surviving populations The discovery of Harriet and the results that come from the constant scientific research conducted by both staff at the CDRS and visiting scientists help us all in the task of conserving these fascinating reptiles for generations to come.
In conclusion I would like to thank the British Chelonia Group for the kind donation of £1200 towards the purchase of a centrifuge, a vital piece of equipment necessary in trying to determine the cause of the recent tortoise fatalities on Santa Cruz island I must thank my fellow trustees, members and volunteers of the Galapagos Conservation Trust whose support gives me hope that we in Britain can play our part in helping to conserve the islands of the galapagoes And last but not least, to my crazy eccentric fellow naturalist guide, David Day, whose relationship with these innocent creatures gives a whole new meaning to "togetherness".
Beebe, W. 1924 Galapagos, World's End - An account published under the auspices of the New York Zoological Society Published by G. Puttnam's & Sons (New York and London).
Perry, R. 1984 Key Environments GALAPAGOS Pergamon Press Ltd Photographs by Jon Tee-Van Taken from Galapagos, World's End.
Testudo Volume Four Number Four 1997