THE GECKOS OF NEW CALEDONIA

Image 1: The Balancing Hunter. Gargoyle gecko, Rhacodactylus auriculatus. The gargoyle gecko, Rhacodactylus auriculatus is an accomplished predator that is capable of killing other lizards (Bauer, 2013:89). Their mouths are lined with long, sharp teeth that pierce the skin of their prey (Bauer and Sadlier, 1994; Bauer, 2013:53). Despite this, they will often favour fruits, flowers, and insects, resulting in one of the broadest diets of any gecko (Bauer, 2013:89). Although they live within the trees of New Caledonia's subtropical rainforests, they descend to the foliage on the ground to search for food (Bauer and Sadlier,1994). Here, they regularly face unfamiliar and challenging terrain. To help them balance, they tread cautiously with slow, small steps and position their body as low as possible. Adhesive toe pads provide extra grip and even allow them to climb vertically (Saraf, 2016). This mastery of movement makes it almost impossible for their victims to escape, playing a crucial role in gargoyle geckos success as predators. Image 2: The Colour Changer. New Caledonia giant gecko, Rhacodactylus leachianus. The Earth's largest living gecko is appropriately named the New Caledonia giant gecko, Rhacodactylus leachianus. Adults can grow to over 10 inches long and live within the trees of the island's subtropical rainforests (Bauer, 2013:18). As a nocturnal species, they spend the day resting and only become active after the evening's vibrant orange sun has set (Sound et al., 2018). Because of this, they rely on a range of techniques to keep them hidden from predators like wild cats and rodents (Sadlier et al., 2017; Palmas et al., 2017). Creases of excess skin merge seamlessly with the surface beneath them to hide their profile (Bauer, 2013:32). Like other geckos (Vroonen et al., 2012), their skin is also able to change colour to match surrounding levels of light (Rutland et al., 2019). Although very little is known about how they produce this colour changing response, further scientific research will allow us to understand exactly how these enormous creatures remain out of sight. Image 3: The Aerial Escapist. Crested gecko, Correlophus ciliatus. Historically, very little was known about crested geckos, Correlophus ciliates. So much so, they were even considered to be extinct until the early 1990s, when they were rediscovered (Bauer, 2013:109). Since then, scientists have started to understand their astonishing behaviours in greater detail. Navigating the dense subtropical rainforests of New Caledonia (Kubiak, 2020:243) isn't easy for crested geckos. They have developed a powerful leap, thought to allow them to escape from predators. After propelling themselves away from danger, they curve their bodies to increase the time they make contact with the landing surface. Because of this, as they plummet towards the ground, lower impact forces and a cushioned fall lessen the chances of injury (Higham et al., 2021). To ensure the perfect landing, they use their tail to alter the angle of their body mid-flight (Grabar, Gilman and Irschick, 2016). This discovery is just the beginning. Imagine the countless behaviours of other species that are yet to be uncovered.

References: Bauer, A.M. 2013. Geckos: The Animal Answer Guide. Baltimore: Johns Hopkins University Press.

Bauer, A.M. and Sadlier, R.A. 1994. 'DIET OFTHE NEWCALEDONIAN GECKO Rhacodactylus auriculatus (SQUAMATA, GEKKONIDAE). Russian Journal of Herpeloral, M. 2016. Analysis Of The Crested And Gargoyle Geckos Locomotion And Toepad Activity On Horizontal And Vertical Poles Of Varying Thickness, BA(hons) Thesis. Mount Holyoke College. Grabar, R.D., Gilman, C.A. and Irschick, D.J. 2016. 'Effects of Surface Diameter on Jumping Kinematics and Performance in Two Arboreal Gecko Species (Correlophus ciliatus and Rhacodactylus auriculatus). Herpetologica, 72(1), pр.32-39. Higham, I.E., Hotmann, M.N.S., Modert, M., Thielen, M. and Speck, T. 2021. 'Jumping with adhesion: landing surface incline alters impact force and body kinematics in crested geckos. Scientific Reports, 11(23043). pp. 1-13. Kubiak, M. (ed.) 2020. Handbook of Exotic Pet Medicine. New Jersey: John Wiley & Sons. Palmas, Pet al,. 2017. 'Feral cats threaten the outstanding endemic fauna of the New Caledonia biodiversity hotspot. Biological Conservation, 214, pр.250-259. Rutland, C.S. et al,. 2019. 'Reptilian Skin and Its Special Histological Structures. Veterinary Anatomy and Physiology. IntechOpen.

Sadlier, R.A. et al, 2017. New Caledonia Giant Gecko, Rhacodactylus leachianus. [online] IUCN Red List of Threatened Species. Available at: https:// www.iucnredlist.org/species/176166/123252801.

Sound, P. et al, 2018. Thermal ecology and habitat utilization of Rhacodactylus leachianus from New Caledonia

Vroonen, J. et al, 2012. 'Physiological colour change in the Moorish gecko, Tarentola mauritanica (Squamata:

Gekkonidae): effects of background, light, and temperature. Biological Journal of the Linnean Society, 107 (1). pp. 182-191.