17

The Reality of Giant Geckos

I grew up reading National Geographic, which in those days ran advertisements in the back for international airlines and freighter ships on which one could book passage. I wrote away to them all and received a lot of mail for an eight-year-old. Most were brochures, but some included novelties, like plastic tikis the color of jade from Air New Zealand. Having already decided that I was going to be a herpetologist (a decision cemented in stone by the capture of a Smooth Green Snake at the age of five) I envisioned myself in the tropics catching reptiles; I had not yet reached the stage of considering why I would be catching them or what I would be doing with them. In 10th grade I read Mutiny on the Bounty in class, and this kicked off months of delving into eighteenth- and nineteenth-century literature of exploration in the South Pacific.

Years later, when the time came to pick a project for my doctoral research, I looked for a way to combine my interest in lizards, and geckos in particular, with something that would necessitate travel to the South Pacific. I found what I was looking for in a 1964 paper by the great German herpetologist Robert Mertens. It provided information on the morphology and behavior of captive New Caledonian Giant Geckos (Rhacodactylus leachianus). These lizards—the largest geckos in the world—had distinctive short but prehensile tails, and despite their massive size (for a gecko), they were virtually unknown. I discovered that the most recent extensive herpetological field work in New Caledonia had been undertaken by the Swiss zoologists Jean Roux and Fritz Sarasin in 1911–1912 and that little had been done since. In the year that followed, I immersed myself in what literature there was on Rhacodactylus and its relatives and familiarized myself with Roux’s sepia-toned photos of exotic sounding localities like Oubatche, Bopope, the Ngoï Valley, and the Roches de Hienghène. I also wrote away, largely unsuccessfully, to determine if permission to collect reptiles in this French territory needed to come from Paris or from the territorial capital of Nouméa. In the end, no one responded and, armed only with the name of a potential contact in the largest nickel mining company on the island—a possible source of access to land on which I could collect—I winged my way into the great unknown.

My path to New Caledonia took me the long way around the world. I left California for two months of museum work in Europe and then, after a short stay in Thailand (just long enough to get malaria), I went to Australia. There I visited major museums and carried out fieldwork in South Australia, Western Australia, and the Northern Territory. Although the distance was no greater then than now, in the pre-cell-phone, pre-internet era, home certainly felt much farther away, and one had to consider the implications of working remotely or working alone in the field, or both, when there was no way to call for assistance. Fortunately, I was young and stupid and, like most 22-year-olds, immortal (in my own mind); thus, the lack of communication posed no impediment to my research. I visited spectacular landscapes, made lifelong friends, saw my first agamids, varanids, and elapids and caught my first geckos and pygopods. I also managed to wreck a rental car, necessitating a 20-mi walk to the nearest town, and got lost while collecting at night in the stone country of Kakadu National Park.

After crossing the Coral Sea and the outer reefs of New Caledonia I landed at the international airport in Tontouta, which still had a bit of the feel of a French outpost in the Pacific, complete with patrolling gendarmes. Then, as now, most of the tourist infrastructure was centered on Nouméa, but the capital retained vestiges of its past, like the Place des Cocotiers in the town center and the offices of the South Pacific Commission (now Pacific Community), which at the time occupied a former World War II American military base near the beach at Anse Vata. I paid my respects at the nickel company where my contact, who had never responded to my letters, had apparently long before retired. Thankfully, his replacement, despite knowing nothing about me or my research, arranged a car for me and put me in touch with the permit authorities so I could begin to collect specimens across the island.

Leaving Nouméa, I found the landscape became decidedly more rural going up the west coast, but it was largely agricultural. However, always to the east, the mountains of the Chaîne Centrale beckoned with the promise of forests filled with geckos. Although roads on the west coast were mostly paved, those crossing the mountains were only partly so, and on the east coast, dominated mostly by scattered Kanak (local Melanesian people) villages, even the main road was unpaved outside the few larger towns. In the far northeast of the island the road ran out at the mouth of the wide Ouiaème River, and a small ferry was (and remains) the only means of reaching the foot of the Panié Massif—at 1628 m the highest peak on the island and a well-known site of both floral and faunal endemism.

Driving around the island I soon discovered that my car overheated on any incline, necessitating frequent stops, which provided (or forced) opportunities to collect. I quickly got the knack of catching the terrestrial skinks and the smaller geckos in their daytime retreats. With the reptile fauna nearly entirely endemic, every species was new to me and fascinating in its own right. The skinks, in particular, had not been revised in decades, and most were allocated to one of a few large trash bin genera for convenience, but their real affinities were unknown. With no field guides to the island’s fauna, I worked mostly from Roux’s 1913 monograph and from notes provided by Ross Sadlier at the Australian Museum who, like me, had seen New Caledonia as a fruitful area of study and had traveled there a few years earlier to begin a study on skinks. I had not been successful with the giant geckos, however. Although my headlamp had seemed to work all right in open habitats in Australia, I soon discovered that for night work it was not up to the task of eye-shining in the forest. My nocturnal take was mostly limited to the smaller geckos of the genus Bavayia, which were often active on low perches or tree trunks. After several weeks, as my time in New Caledonia was ticking away, I had yet to find the giant geckos I was after. In the south of the island, I was able to get Gargoyle Geckos (Rhacodactylus auriculatus), now popular in the pet trade, but then a species that few herpetologists had seen alive. These lizards, with their knobbed skull ornamentation, were often active on low perches and, as I was to discover some years later, were unique in that they regularly fed on flowers, tree sap, and other lizards, in addition to the staple gecko diet of arthropods.

Eventually I heard of someone in a tiny village in the Vallée d’Amoa in the northeast of the island who knew the truly giant geckos, which are locally referred to as caméléons and feared because they are wrongly believed to be venomous. I arrived at my contact’s house just as darkness fell, and he told me he had seen them recently on a particular tree. Despite my inadequate headlamp I hoped that knowing precisely where to look would increase my odds. I still could not make out the red eyeshine of these massive geckos, but I was able to make out a body outline at the edge of my light. Although I could see only a bit of the animal, it was enough to confirm its identity. I broke off a long thin branch from a nearby tree and tried to get the end of it above the gecko, which was pointed upward on the tree trunk and had begun to move upward when disturbed by the light. At about 15 ft above my head it was too far for me to reach, so I tried a wrist rocket slingshot that I had with me. After a few misses in the dark I was able to hit the trunk just above the gecko, which stopped its upward climb. By shining the light above the gecko, it was induced to move downward, and when it got within range of my branch I flicked it off the trunk and caught it as it fell. At about 22 cm in head and body length it was nowhere near a record size, but it was larger than any other gecko I have ever seen and, indeed, bigger than any other living species of gecko. Its abdomen was soft and fleshy, but the animal as a whole was very muscular and powerful and it let out a loud, deep guttural distress call typical of the species. I could feel both its huge toepads and small but needle-sharp claws hanging on to me and could see the adhesive pad on the tail that Mertens had written about and that had first piqued my interest. In that instant Rhacodactylus leachianus became real to me.

Although over the years I have worked on species I have not seen or collected in the wild, I feel I never really know an animal unless I have seen it in the field. Even a fleeting glimpse of a species suffices to move it from an almost abstract concept, represented by measurements or characters, to something imbued with a gestalt that renders it more than the sum of its parts. Seeing that first giant gecko moving in the periphery of my light not only fixed a search image in my mind but gave me insight into how this species lives and what its ecology and behavior might be like. I have relived that moment hundreds of times with every new reptile or amphibian species I have encountered in the field. Although I may not have a precise recollection of every locality where I found a given species, I do retain an almost photographic-quality memory of its immediate surroundings, its posture, its movement, and the minutiae of its appearance. For places like New Caledonia or southern Africa, where I have been on dozens of field trips, the sum of these memories has, over a period of decades, contributed to a more comprehensive feel for how entire herpetofaunas function and how they may have evolved.

But that initial impression, of necessity, gave way to the practical need of securing my captive, which I transferred to a cloth bag that I tied with the tightest knot I could. Fresh off my victory, within minutes I found another, though smaller, gecko closer to head height on a trunk. I recognized it as another species of giant gecko, Rhacodactylus (now Mniarogekko) chahoua. If anything, this was even more exciting, as this species had been described in 1869 and not seen again until more than 100 years later. It, and a second specimen collected on an adjacent tree, became the nucleus of my first research paper in which I designated it as the neotype of the species, replacing the original name-bearing holotype, which had gone missing sometime after 1883. Although it had taken me until the end of my stay to finally collect these giant geckos, I returned to Nouméa satisfied with the trip and ready to ship the lizards back to the United States. The night before packing the lizards for their long flight (I still had a month of fieldwork in New Zealand before heading home), I discovered that the bag containing my only Rhacodactylus leachianus was empty. I looked everywhere without success and went to sleep thoroughly defeated, a major aim of my trip unfulfilled due to my carelessness. But, snatching victory from the jaws of defeat, the next morning a final search revealed that the gecko had managed to get into a rolling window shutter, apparently by lifting an impossibly heavy access panel with its head.

Armed with a far better headlamp and the knowledge gained on that first trip, I returned to New Caledonia five more times during my doctoral studies and a dozen more after that. On every trip, lost species were rediscovered or new species were found, and for each of these there is a stored snapshot in my brain of that first view of something new. These images recall that visceral sensation of discovery and fuel my enthusiasm for the next field trip, and the next, and the next.