Taxonomy
Common name :
Le Gecko rayé du Mt Taom
Mt Taom Striped Gecko Red List Status -
Critically Endangered (CR) , assessed in 11/12/2017Protected species -
in Southern Province , in Northern Province
Description
Description:
A small relatively stout species of gecko growing to a body length of 45mm with a short tail 102% that of the body. It has moderately broad toes. The colour pattern on the body is highly variable, but typically brown above with vague narrow beige and brown longitudinal stripes from the top of the eye to above the hindlimb, and darker on the side of the body – some individuals nearly a uniform yellowish brown overall.
Natural distribution:
Known only from Mt Toam in the northwest ranges.
Distribution within Province Nord: see above.
Habitat:
Mid to high elevation maquis shrubland.
Threats:
-
potentially high level of threat to mid and high elevation maquis shrubland in access and mined areas of Mt Toam through activities associated with mining.
-
moderate to high level of threat to mid and high elevation maquis shrubland on Mt Toam from spread of fire from adjacent low elevation farm land.
-
moderate to high level of threat at low elevation sites from predation by introduced rats and cats.
Conservation Status: Critically Endangered.
Dierogekko thomaswhitei has an extremely restricted distribution (<100km2). Current mining activities are concentrated at 800-880 metres elevation on the western end of the massif though an access road to the mine traverses this end of the massif from about 340 metres elevation. A network of old exploration tracks extends along the summit region of the remainder of the massif. Mining activity on the western end of the massif (including the access road) impacts directly on the species preferred habitat and results in both a decline in extent and quality of the of the maquis shrubland from which this species is known, for this reason it has been placed at a high level of threat (Bauer et al., 2006) and considered to meet the criteria to be categorised as Critically Endangered.
*Species occurring in localised areas of maquis shrubland are highly susceptible to catastrophic impact wildfires, and require pro-active conservation management to deal with this potential threat.
Dierogekko thomaswhitei is listed as Critically Endangered because it has a very restricted distribution, is present in only one location, and there is continuing decline in its extent of occurrence, area of occupancy the extent and quality of its habitat and the number of subpopulations and mature individuals. There are ongoing threats from mining, invasive species, and wildfires.
Geographical area
Dierogekko thomaswhitei is endemic to Province Nord, New Caledonia. It is known only from the Ouazangou-Taom massif, north-western Grande Terre (confirmed only from Mont Taom). It occurs at elevations between 300 and 1,000 m. The extent of occurrence and the area of occupancy are estimated to be 8 km2.
Population
There is no information on present population density or trends although this species can be locally abundant in favourable habitat. It is presumed to have suffered a significant reduction in population size and extent with habitat loss and degradation resulting from wildfires and past mining activities.
Habitat
Dierogekko thomaswhitei inhabits rocky maquis shrublands at mid- to high elevation and low closed montane forest. It is nocturnal and arboreal, sheltering beneath stones by day, and climbing into the vegetation at night.
Threats
There is an active nickel mine within the range of Dierogekko thomaswhitei and it is expected that its area of operation will be extended, threatening a significant part of the gecko habitat. Wildfires are a recurrent threat, particularly at lower elevations. Rodents and feral cats are abundant on the Ouazangou-Taom massif and are expected to exert a predation pressure (Palmas 2017, Thibault 2017). The presence of Wasmannia auropunctata on Taom is expected to have also a consequent detrimental impact on the geckos (Jourdan et al. 2000, 2001).
Conservation
Protected in Province Nord under Code de l'environnement de la Province Nord (Délibération No. 306-2008/APN, 24 October 2008) and in Province Sud under Code de l'environnement de la Province Sud (Délibération No. 25-2009/APS, 20 March 2009). This species is not present in any reserve and no conservation management is currently being undertaken.
Bibliography
Bauer, A.M., Jackman, T., Sadlier, R.A., Whitaker, A.H. 2006. A revision of the Bavayia validiclavis group (Squamata: Gekkota: Diplodactylidae), a clade of New Caledonian geckos exhibiting microendemism. Proceedings of the California Academy of Sciences(57) , p.503–547.
Jourdan, H., Sadlier, R.A. and Bauer, A.M. 2000. Premières observations sur les conséquences de l’invasion de Wasmannia auropunctata 1863 (Roger) sur les prédateurs supérieurs dans les écosystèmes Néo-calédoniens. Actes des collectes insectes sociaux(13) , p.121-126.
Jourdan, H., Sadlier, R.A. and Bauer, A.M. 2001. Little Fire Ant Invasion (Wasmannia auropunctata) as a threat to New Caledonian lizards: Evidences from a sclerophyll forest (Hymenoptera: Formicidae). Sociobiology(38) , p.283-301.
Palmas, P., Jourdan, H., Rigault, F., Debar, L., De Meringo, H., Bourguet, E., Mathivet, M., Lee, M., Adjouhgniope, R., Papillon, Y. and Bonnaud, E. 2017. Feral cats threaten the outstanding endemic fauna of the New Caledonia biodiversity hotspot. Biological Conservation(214) , p.250-259.
Uetz, P. (ed.) 2017. The Reptile Database.
Thibault, M., Brescia, F., Vidal, E. and Jourdan, H. 2017. Invasive rodents, an overlooked threat for skinks in a tropical island hotspot of biodiversity. New Zealand Ecological Society(41) , p.74-83.
IUCN 2021. The IUCN Red List of Threatened Species. Version 2021-2.
Experts
Assessor(s): Sadlier, R., Bauer, A., Jourdan, H., Astrongatt, S., Deuss, M., Duval, T., Bourguet, E., McCoy, S., Bouteiller, A., Lagrange, A.
Reviewer(s): Cox, N.
Contributor(s): Whitaker, A.
Facilitator(s): Warimavute, G., Tanguy, V., Lietar, J.