Giant bronze gecko (Ailuronyx trachygaster)
Classified as Vulnerable (VU) on the IUCN Red List (1).
Like all geckos of the Ailuronyx genus, the giant bronze gecko is endemic to the Seychelles islands (2). This enigmatic species is rarely seen due to its preference for remaining high above the ground, and also because of its sandy-bronze colouration, which camouflages it against the stems and branches of its preferred tree, the coco-de-mer palm (Lodoicea maldivica) (3).
Confined to the Seychelles islands of Silhouette and Praslin (1).
This arboreal, canopy-dwelling gecko is found in tropical forest with a canopy over 15 m (1).
Only limited information is available on the ecology of the giant bronze gecko, but comparison with its two close relatives, the bronze gecko (A. seychellensis) and the dwarf bronze gecko (A. trachyscopaeus), provides some further insight (2).
A pattern of vertical stratification is believed to exist, in which the giant bronze gecko, the largest of the three species, dominates the canopy, forcing the smaller sized animals into lower vegetation and tree trunks. This pattern has been observed in other gecko species (Phelsuma day geckos), and correlates with the pattern of distribution found between these three bronze gecko species. Although the bronze gecko may occur in the canopy, it will tend to be forced out where the giant bronze gecko is present. By dominating the canopy, the giant bronze gecko feeds on the most nutritional food sources that, at least on Praslin, comprise the flowers of the coco-de-mer palm. During the day, this species feeds exclusively on the nectar and pollen of the male flowers, biting them to stimulate nectar flow and sometimes consuming the flower. Insects, which supplement the diet of the bronze gecko, may also be eaten by the giant bronze gecko at night, but there is no direct evidence of this (2).
This species’ reproductive biology is unknown (1).
Although there is no evidence of a decline, the giant bronze gecko is considered vulnerable to extinction due to the small and restricted nature of its range, with populations known from just two small islands. Thus, any habitat degradation within this restricted range, such as through the spread of invasive plant species, could have a dramatic impact on the gecko (1).
The giant bronze gecko and its habitat are protected within Praslin National Park (1), and alien plant control is being undertaken on the island (4). Habitat restoration programmes are also being conducted to help this species on Silhouette (5), where it has been suggested that forest habitats on the island could benefit further by being included in a new protected area (1).
Authenticated (20/11/2006) by Justin Gerlach, Scientific Co-ordinator, The Nature Protection Trust of Seychelles.
- Arboreal: living in trees.
- Endemic: a species or taxonomic group that is only found in one particular country or geographic area.
- Nocturnal: active at night.
- Stratification: division into groups, such as division of a forest, or any ecosystem, into distinct layers (or strata) of vegetation, such as canopy, herbaceous vegetation and understorey.
IUCN Red List (December, 2008)
- Gerlach, J. (2004) The Enigmatic Giant Bronze Gecko Ailuronyx trachygaster - Part 2: Ecology. Gekko, 4(1): 8 - 14.
- Gerlach, J. (2005) Ailuronyx trachygaster – the Best View Yet!. Gekko, 4: 31 - .
Seychelles Islands Foundation (December, 2008)
The Nature Protection Trust of Seychelles (December, 2008)