Day geckos (Phelsuma astriata and Phelsuma sundbergi)…

Visitors to Denis will all notice the bright green geckos that can be seen on the trunks of coconut trees and at night on the columns in the restaurant – where they lie in wait by a light to capture the insects it attracts.

There are in fact two species of day gecko to be found on the island the Lesser day gecko (Phelsuma astriata) and the Day gecko (Phelsuma sundbergi). Both species are endemic to the granitic Seychelles but are believed to have both been introduced (presumably inadvertently) to Denis. Gerlach (2007) states that P. sunbergi was first recorded on Denis in 1908 whilst P. astriata was introduced as recently as 1981. Of course lizards can and are known to colonise distant islands via floating vegetation so such matters are never entirely clear cut but the apparent recent nature of these colonisations does very much suggest a human vector. Regardless both of these species are now well established on the island and as species endemic to the central archipelago are more than welcome.

P. sundbergi is the much larger and heavier set species (getting up to about 20cm long including its tail) when mature and tend to be territorial. Typically one will be evident per coconut trunk or column on a boat shed or verandah and when two occur they will often be seen to fight. They are particularly noticeable to visitors as it is this species that populates the columns around the restaurant. They are typically bright green with on closer inspection, a light red freckling on the back of some individuals.

P. striata is significantly smaller (10 -12 cm including tail) and much less sturdy in build than P. sunbergi and can be seen on vegetation, tree branches, palm leaves and also on walls. It has visible pale belly and interesting red patterning on the bright green of its back and head. The adult has a distinctive red chevron on its head typically followed by two transverse bars on its neck (see photo in sidebar – this specimen has dots rather than the bars but it was a juvenile and the bars may form later). They typically have a spinal red line with patterns of red dots. On Denis these dots often merge to form a herringbone pattern (see sidebar). Occasionally a black P. striata can be seen this colour change is a reversible defensive stress response.