Research
Survey of the lizard fauna in Sclerophyll forest at Tia
Study area
Remnant Schlerophyll forest along the creek edge in Pouembout Valley.
Gaeac shrubland adjacent to Schlerophyll forest.
The survey of reptile species at the Tia Sclerophyll Forest was undertaken as part of the IRD (Institut de recherche pour le dèveloppement, Nouvelle-Calèdonie) biodiversity assessment of forest aimed at making an inventory several faunal groups that could later be used to monitor future changes in species abundance and composition.
The study site is located on grazing land in the Pouembout Valley . It is a remnant forest of approximately 40 ha, and includes a gallery forest along the creek. The area adjacent to the forest consists of a transition zone of gaeac shrubland (a typically dense acacia woodland of the species Acacia spirorbis) or cleared grazing pasture.
The sampling program took place at the end of the summer wet season in April 2000. Two quantitative sampling methods were used: sticky traps on trees to sample arboreal lizards and pitfall traps to sample ground dwelling lizards. Timed visual search periods were also conducted along transects to complement the trapping program.
The lizard fauna
Nine species of reptiles in total were recorded during the course of the survey from pitfall trap captures and during timed transects. This included:
- four species of skink; the Speckled Litter Skink, Caledoniscincus atropunctatus; the Strand Litter Skink, Caledoniscincus haplorhinus; the Golden Litter Skink, Caledoniscincus auratus; and the Green-bellied Tree Skink, Lioscincus nigrofasciolatum.
- four species of gecko; the Sclerophyll Bavayia, Bavayia exsuccida; the Forest Bavayia, Bavayia cyclura; the Fox Gecko, Hemidactylus garnoti; and the Pacific House Gecko, Hemidactylus frenatus
- the typhlopid snake, the Flower Pot Snake, Ramphotyphlops braminus.
The three species of Caledoniscincus were all recorded in the forest, but only Caledoniscincus haplorhinus was recorded from adjacent pasture and gaeac shrubland. The arboreal skink Lioscincus nigrofasciolatum was recorded at both trapping sites in the forest and was observed in other parts of the forest during the course of transect surveys.
Two species of geckos, Bavayia excussida and Hemidactylus garnoti, were recorded only from the trap site in which fire ants were not present. Bavayia cyclura was recorded from both trap sites and was also encountered during the course of opportunistic day searching of shelter sites and at certain points around the perimeter of the forest during the course of night searches. Hemidactylus frenatus was recorded opportunistically from gaeac shrubland around the perimeter of the forest, but not from trap sites within the forest.
The Speckled Litter Skink Caledoniscincus auratus.
Two species of lizard, Bavayia exsuccida and Caledoniscincus auratus, have restricted distributions and are of particular conservation concern. Both species are only known from a few locations in lowland forests of the north west coast. The distribution of both species is constantly being revised as survey work in this part of the island improves our understanding of the species ranges.
The gecko Bavayia cyclura almost certainly consists of several cryptic species and the affinities of the population at Tia are currently being investigated. It is very abundant in sclerophyll forest habitat and the remaining habitat could be of particular importance for the conservation of the species in this part of the island.
Results – impact of the Little Fire Ant
The impact of the invasive Little Fire Ant, Wasmannia auropunctata, was more difficult to assess in the Tia forest. Most of the pitfall trap captures were the ground dwelling species Caledoniscincus haplorhinus and Caledoniscincus auratus, with almost 2.5 times as many more individuals recorded for each species in the uninvaded site. Differences in abundance between invaded and uninvaded forest for the dominant arboreal species, Bavayia cyclura, were confused by an exceptional event in which 10 individuals were recorded on a single trap one night.
The results of our research in the Tia forest has several implications important for conservation of the lizard fauna of sclerophyll forests. Firstly, different patches of sclerophyll forest, even in close geographical proximity, can have different components to the lizard fauna. The Pindaû and Tia forests are only 25 km apart but Caledoniscincus auratus is clearly absent from the Pindaû forest and genetic studies in progress also indicate significant differences between the populations of Bavayia cyclura at each location.
The impact of the invasive Little Fire Ant on the lizard fauna at Tia is less clear, although there appears to be a clear difference in abundance of the common terrestrial skinks in the invaded and uninvaded areas studied. There is less conformity of structure of the forest at Tia and the distribution of the ant at this location is more difficult to assess and may require more intensive sampling to establish a pattern of impact by ants.
Copyright © Australian Museum, 2002
