This study arose from a conservation dilemma between the need to
conserve a population of the endangered pink tailed legless lizard, Aprasia
parapulchella and crucial upgrading of Canberra's sewerage treatment plant.
The study focused on conservation biology and how it could be applied to the
management of A. parapulchella. As little biological information was available
on A. parapulchella, research was focused on obtaining data that would be
beneficial in the conservation management of the species. This included the
dietary and habitat requirements, population status and structure and population
relocation and habitat restoration.
A. parapulchella was found to occur in low relative densities at all sites
(maximum 9.1 lizards per 1000 rocks turned, Mt Taylor). Populations of the
species appear to be larger than has been considered previously, however
numbers are still below 500 individuals per site. Sexual dimorphism is present in
the species with females achieving longer snout-vent lengths than males. Sex
ratios were equal in all sites, however average size of lizards was different at the
four main study sites, indicating differences in population structure. The life
history of A. parapulchella can be summarised as long-lived, late maturing (3rd or
4lh year of life) with a low reproductive rate (single clutch of two eggs per year).
A. parapulchella is a dietary specialist feeding on about 11 different
species of ants. Interestingly, the lizards also live with the same species that they
feed upon. By far the most important species in the diet and homesite
requirements of A. parapulchella is the ant Iridomyrmex rufoniger. A.
parapulchella shows positive selection towards the species in homesite choice, is
found most commonly in the nests of this ant, and selects its brood over the
brood of other ant species in diet experiments. In addition this ant was
represented in the diet of A. parapulchella more commonly than any other ant.
The relationship between ants and A. parapulchella appears to be unique and the
mechanisms of this specialisation require further investigation.
The vegetation associations where A. parapulchella occur are different
across the range of the species. Sites at Bendigo and West Wyalong support
mallee communities, while in the ACT region, Bathurst and Tarcutta, A.
parapulchella appears to be a habitat specialist, being found most commonly in
sites dominated by grass species, both native and introduced. A. parapulchella
lives beneath rocks in grassland sites. Rocks that the species uses for homesites
are commonly between 100 and 150 mm wide, 120-220 mm long and 50 and 150
mm thick. There were significant differences between the sizes of rocks used at
different sites and between different seasons. Rocks used by females were
significantly larger than rocks used by juvenile lizards. Twelve other species of
reptile were found to use rocks in grassland sites, with rocks partitioned within
the community on the basis of size and shape.
An experimental relocation of A. parapulchella was conducted to try to
determine ideal habitat conditions for the survival of relocated individuals.
Unfortunately of the 114 lizards released, only 15 were recaptured. Although
recaptures were low, trends indicated that treatments of Themeda triandra and
very high rock densities had the highest survival rates. Key habitat variables
were reinstated at the Lower Molonglo Dam site however restoration is
preliminary with more time needed for the habitat to be suitable for occupation
by A. parapulchella.
What started as a situation that was likely to have a deleterious impact on
A. parapulchella has been turned into a conservation success story. Without the
involvement of ACT Electricity and Water, much of the basic biology of A.
parapulchella would still be unknown. The findings will now form a solid basis
from which to effectively conserve A. parapulchella. The project provides an
example of the conservation success that can be achieved between industry and
conservation partnerships.
| Identifer | oai:union.ndltd.org:ADTP/219070 |
| Date | January 1999 |
| Creators | Jones, Sandra Raelene, n/a |
| Publisher | University of Canberra. Applied Science |
| Source Sets | Australiasian Digital Theses Program |
| Language | English |
| Detected Language | English |
| Rights | ), Copyright Sandra Raelene Jones |
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