Suchergebnisse

Context The deliberate accumulation of faeces or scats in one location is a common behaviour used for social signalling. The endangered pygmy bluetongue lizard, Tiliqua adelaidensis, is a solitary-living species that appears to use scats as social signals. Previous studies have found that these lizards approach burrows more cautiously if there is a conspecific scat present and behave differently to scats from male and female conspecifics, indicating that these lizards can recognise scat-based conspecific cues. For endangered species, understanding how an animal uses and responds to chemical cues has the potential to become a powerful tool in conservation management. Aims To investigate whether these solitary lizards might be using scats as social signals by testing whether scats were being deposited in a non-random pattern designed to maximise their exposure to the nearest neighbour conspecifics. Method In the present study, we investigated the spatial pattern of scatting behaviour by pygmy bluetongue lizards in the field. Results Scats were consistently deposited in one direction that was significantly aligned with the nearest occupied burrow of a neighbouring lizard. The same deposition sites were used when previous scats were either destroyed by rain, or experimentally moved to a different location. Male lizards deposited scats significantly closer to their own burrows when neighbours were closer. Key conclusions The results were consistent with the lizards using scats to advertise their presence and status. The scat-deposition patterns observed in the present study suggest that scats are used as an olfactory signal associated with social organisation of pygmy bluetongue lizards. Implications Current plans for the conservation management of this endangered species include translocations. By understanding how these lizards respond to, and use chemical cues, we may be able to use this knowledge to aid in translocation programs, e.g. by pre-establishing territories for individuals before they are introduced into the population.

Context
The use of artificial refuges is a common strategy for the conservation management of endangered species. However, artificial refuges may alter an animal's natural behaviour that in turn may be detrimental to the species. The endangered pygmy bluetongue lizard from Australia is one species that will accept artificial burrows.

Aims
The aim of the present research was to determine whether the normal behaviour of the pygmy bluetongue lizards differed between artificial and natural burrows, so as to determine whether the existing artificial burrow is an optimal design for this species.

Methods
In the present study, we filmed the behaviour of lizards as they entered artificial and natural burrows. We compared the number of times a lizard entered a burrow, the time that lizards spent inspecting burrows, and the behaviours that lizards used when entering artificial and natural burrows.

Key results
We found that in natural burrows, lizards always entered head first, and then usually reversed direction inside, using an enlarged basal chamber, to sit with their head uppermost in the entrance. In artificial burrows, however, lizards had to enter head first, then reverse tail-first back out, and then reverse tail-first back into the burrow (so as to have their head facing upwards) We called this behaviour reversing from outside.

Key conclusion
The stereotyped reversing-from-outside behaviour when entering artificial burrows, and its occasional occurrence in natural burrows, suggest that it has evolved to allow lizards to use narrow burrows as well as those with a chamber, even though it can increase lizard's surface activity and exposure to predation.

Implication
The reversing behaviour from outside the artificial burrow increases exposure to potential predators, and our observations suggest that a re-design of artificial burrows to incorporate internal space for turning around may improve their effectiveness in conservation management interventions.

Understanding the potential threats of predation can play a crucial role in conservation management of threatened species. We investigated the frequency of sublethal injuries to live individuals of the endangered pygmy bluetongue lizard (Tiliqua adelaidensis). We found that there was no significant difference in the frequency of injury between males and females. However, there was a significant difference in injury frequency between adults and subadult animals and also between two close, but isolated, populations of pygmy bluetongue lizards. These data can be used, with caution, to understand the predation risks in natural populations of this species. They also suggest that predation would be a significant hazard that must be considered in any translocation program that is considered for this species.

Context
Translocation has become an increasingly common tool in the conservation of species. Understanding the movement patterns of some species can be important to minimise loss of individuals from the translocation release site.

Aims
To describe seasonal and sex-biased movements within populations of an endangered Australian lizard.

Methods
We monitored seasonal movement in the endangered pygmy bluetongue lizard (Tiliqua adelaidensis) by using pitfall trapping, with a total of 49 440 trap-nights from three sites over 2 years. Other studies have shown that individual pygmy bluetongue lizards normally remained closely associated with their spider burrow refuges, with very little movement. Thus, we interpreted any captures detected through pitfall trapping as out of burrow movements. We investigated whether there was any seasonal, age or sex bias in moving individuals.

Key results
We found that male pygmy bluetongue lizards were more likely to move than were females. After adults, neonates were the second-most captured age class. Spring was the peak movement time for adults, whereas movement of neonates occurred in autumn.

Key conclusions
The majority of movement can be attributed to males in the breeding season, whereas females move very little.

Implications
The present study provides some baseline data that would allow more informed decisions about the most appropriate individuals in a population to choose for a translocation program and the times to conduct translocations to allow the maximum chance for establishment.

Habitat fragmentation can have several adverse genetic impacts on populations. Assessing the extent of these threatening processes is essential in conservation management. In the present study, we investigated the genetic population structure of the endangered pygmy bluetongue lizard, Tiliqua adelaidensis, which is now restricted to a few small fragments of its previously more extensive grassland habitat. The aim of our study was to investigate genetic diversity and gene flow both among and within sample sites. The information will assist in making recommendations for habitat conservation and translocation programs. We collected DNA from 229 individuals from six isolated sample sites and genotyped them for 16 polymorphic microsatellite loci. Across all six sample sites, observed heterozygosity ranged from 0.75 to 0.82. There was no evidence of population bottlenecks and little evidence of inbreeding due to consanguineous mating. Genetic differentiation was low to moderate although significant for all pairs of sample sites (FST = 0.021–0.091). Results from Bayesian clustering analyses revealed distinct clusters in the overall sample and suggested restricted gene flow between sample sites separated by distances ranging from 1.7 to 71.6 km. By using spatial autocorrelation, we also found a significant genetic structure within sample sites at distances up to 30 m, suggesting restricted gene flow even in small patches of continuous habitat. It will be important to preserve this finely clustered population structure in captive breeding and translocation programs. Increasing opportunities for gene flow through habitat corridors or population augmentation may help maintain genetic diversity and prevent an increase in differentiation. Although endangered species do not always present model systems for studying fragmentation, our approach shows how important genetic information can be acquired to aid conservation in highly fragmented ecosystems.