Reptiles in dry landscapes

Melissa Bruton, School of Geography, Planning and Environmental Management, University of Queensland

Melissa Bruton with a woma python
Photo © Richard Jackson

Reptile-ecosystem interactions in the sparsely inhabited arid and semi-arid regions of the world are not well understood and one area where reptile ecological research is needed right now is in the southern Brigalow Belt region of Queensland and New South Wales. The Brigalow Belt is a well-known reptile diversity hotspot and there are a large number of species present, including some that are endemic to the region. However, this region has suffered extensive clearing in the past, a practice that continues today though with tighter government regulation. Fortunately suckering of Acacia species allows passive ecosystem recovery in many areas that have been cleared, but it is important to understand how different ecosystem types at different stages of recovery (i.e. cleared, regrowth, uncleared) influence the reptile communities so recovery efforts and future clearing legislation can be guided by accurate information. How do different habitats affect reptile diversity and abundance out here? Why have some species declined and others increased in numbers in altered habitats? What is the cause?

Mulga snake Pseudechis australis
Photo © Melissa Bruton

I suspect that in dry ecosystems, the physical structure and the surrounding landscape are most likely to determine which reptile species are present, how abundant they are, and the condition of individuals but this is yet to be proven. The main goal of my project is to work out how reptile communities differ between areas that vary in ecosystem type, recovery stage, surrounding land use, and physical structure. To do this I have 220 pit fall traps with semi-permanent drift fence lines set up in different ecosystems (Acacia-dominated and Eucalyptus-dominated) at different stages of recovery (cleared, regrowth, uncleared). In November 2010, I started sampling some of the sites using both pit and funnel traps and this summer I will continue pit trapping as well as doing habitat assessments. I am yet to see any trends at this point as this is very early days with trapping expected to take place over both this summer and next summer.

Because pit trapping only samples smaller reptiles, I am also documenting sightings of all the larger species of reptiles within the study area and the habitats they are found in. Detailed research into the habitat use of larger reptile species is lacking because, being top predators, they often have very small sample sizes in reptile research, so they are often excluded from analyses.

A few highlights of the trapping and sightings so far include

• death adders Acanthophis antarcticus (rare in the region)
• pale-headed snakes Hoplocephalus bitorquatus (not often seen)
• Brigalow scaley-foot Paradelma orientalis (Brigalow belt endemic)
• freckled monitors Varanus tristis (shy and elusive)
• narrow-banded sand swimmers Eramiascincus fasciolatus (eastern limit of their range).

It is also promising to see plentiful

• bandy-bandies Vermicella annulata
• coral snakes Brachyurophis australis
• sand goannas Varanus gouldii
• mulga snakes Pseudechis australis
• western brown snakes Pseudonaja nuchalis.

There are also many geckoes (Diplodactylus, Strophurus, Oedura and Rhynchoedura species) and smaller skinks (Ctenotus and Morethia species) currently being trapped and sighted.

Juvenile death adder - Acanthophis antarcticus
Photo © Melissa Bruton

The woma python Aspidites ramsayi is present in the southern Brigalow Belt but rarely seen, however it has been sighted in the study area several times previously. At this point it is unclear if the woma python is rare or cryptic in the region because previous studies in the far western parts of their range indicate that woma pythons spend most of their time sheltering in burrows. It is important to determine if this is also the case with this eastern population of womas. As far as habitat use is concerned, we have anecdotal records but not an extensive understanding of the habitats that woma pythons use and how they use them in dry forested regions. Records of habitat use do exist for other woma python populations but these are in areas with very minimal vegetation. The Brigalow woma python is found in dry forest in an area that is sparsely populated with people so few records exist for the region.

So the second aim of my project is to work out how often and how far woma pythons move and the habitats they use. To do this, I will be implanting radio-transmitters into the body cavity of several larger pythons and radio-tracking them for one year each. With funding from the Wildlife Preservation Society of Queensland and the expertise of Australia Zoo and the Australian Wildlife Hospital we have already implanted a transmitter into one woma python and I have been following him for the last month. Womas are not known to be active at this time of year (spring), therefore we were lucky to find one, and he has proven to be quite a nomad using a range of shelter sites over the spring. As these pythons are rarely seen, we hope to analyse the movements and habitat use of this first snake to best predict where and when to find several more woma pythons to radio-track when they start moving during the breeding season.

Brigalow scaley-foot Paradelma orientalis
Photo © Melissa Bruton

The conservation goals of this project are to understand the influence of ecosystem type, quality and structure on reptile communities and make the information available for informed decision making about land management and clearing legislation within the Southern Brigalow Belt. The decision makers will also have access to detailed habitat use and movement information about the rarely seen and little understood Brigalow woma python, A. ramsayi.