January 3rd 2006
Reptile may be unique to Magnetic
When Magnetic Island scientists published Magnetic Island's World Heritage Values: A preliminary assessment, last year, it was pointed out that, although much of Magnetic Island is protected National Park, this land does not include very much of the populated and rapidly being-developed lowlands. Lowlands support plants and animals not found in the mountainous National Park-protected interior. But, as if to underline the significance of the lowlands, a rediscovery, by Island zoologist, Eric Vanderduys, of a tiny skink - which may be the only animal truly unique to Magnetic- and yet to be found anywhere else than on Magnetic's lowlands, occurred in a leafy back yard in the very heart of suburban Nelly Bay. Following is a article Eric wrote about Magnetic's dwarf skink, Menetia sadlieri and his rediscovery of it.
Magnetic Island Dwarf Skink, Menetia sadlieri
By Eric Vanderduys
As far as excitement per centimetre goes, the tiny Magnetic Island skink, Menetia sadlieri for me, pretty much takes the cake. This diminutive skink measures about 63 mm fully grown. It's not much to look at either - basically shades of brown with some gold flecking and an oily bluish sheen over some of the scales. However, the excitement it afforded was not because of its appearance, but rather its lack thereof.
M. sadlieri was scientifically described in 1991, but this was from a single specimen which had sat preserved in a jar in a museum since 1974. Since then it went unnoticed until 1999 when Dr Alex Kutt of the Environmental Protection Agency found two specimens while conducting fauna surveys for private Nature Conservation blocks on the island. However, these were not collected and no photographs existed.
A tiny juvenile M. sadlieri
I began searching for M. sadlieri in 2003 and did lots of searching in the areas where Alex had found them, even employing pit traps - a favourite of herpetologists - to try and find these shy reptiles. All to no avail. Then one day a slight movement in a leafy suburban back yard caught my eye. With no real effort I had found a juvenile M. sadlieri. If the adults are small, then this was miniscule - measuring just 17 mm from tip of snout to base of tail, and 40 mm total length. Another problem existed - how could I be sure this was M. sadlieri? That 1991 scientific description said that the scales that make this skink different from its nearest relatives are a pair just behind the eye and a single one above the eye. On this juvenile, these scales measured about 0.3 mm for the pair and 0.1 mm for the other, so confirming identity was not easy with the wriggling skink. This skink did prove to be the elusive M. sadlieri, and subsequent searches turned up more than 20 individuals of the species.
However, M. sadlieri remains poorly known. It is currently listed as rare under the Qld Nature Conservation Act and unlisted under the EPBC. It has only been found in lowland parts of Magnetic Island, and it is not known whether it occurs on the granite boulder hills that dominate the island. Within the lowlands, it seems to prefer seasonally dry Melaleuca swamps and areas with thick leaf litter. M. sadlieri may even occur on parts of the nearby mainland, but no targeted surveys have been conducted to clarify this.
Virtually nothing is known of M.sadlieri
Possible threats to M. sadlieri include continued expansion of urban development in Magnetic Island lowlands. Although approximately half of the island is National Park, and the whole island is part of the Great Barrier Reef World Heritage area, little of the coastal lowlands on the island is protected. If these lowlands are the skink's stronghold, then its situation may be dire. It may also be under threat from household cats - despite intensive searching, M. sadlieri has not been located in nearby back yards which have household cats patrolling them regularly.
As for the daily life of M. sadlieri, virtually nothing is known. We do know that one female laid two eggs, each about 7 X 3.1 mm and weighing just 0.05 g, but these failed to hatch in captivity. They do not appear to "sun" themselves like many other reptiles but probably warm up underneath sun-warmed leaf litter, in this way reducing their exposure to potential predators. When they are disturbed they are quick to vanish under leaf litter and even into friable soil.
M. sadlieri is in some ways typical of many Australian reptiles in that its most basic habitat requirements are poorly understood. Generally a perceived lack of charisma means that research dollars go to larger, more exciting, animals, particularly mammals and birds. However, reptiles are critical to the Australian ecology, and gaining a better understanding of their ecology is critical to many species' continued survival. And, for me at least, you get most excitement per millimetre when looking at something tiny like Menetia sadlieri.
Photos: (of Eric Vanderduys) George Hirst
(of Menetia sadlieri) Eric vanderduys