Woma release

In one of the first releases of captive-bred snakes in Australia, woma pythons are to be introduced into the Arid Recovery Reserve near Roxby Downs in northern South Australia. The release is a collaboration between the Arid Recovery Project and Zoos South Australia. Pythons and boas are a group of snakes that are of particular conservation concern throughout the world. This release of woma pythons is not only important for conservation of Australian wildlife, but the release will be closley monitored, enabling us to learn how best to release other endangered snakes elsewhere in the world.

The woma is a large terrestrial python endemic to Australia’s arid zone.  They grow to 2.5m in length, and live mainly in sandy habitats, including the Simpson Desert and Moomba region of South Australia.  They previously occurred in the Roxby Downs region but have become locally extinct, possibly due to fox and cat predation of juveniles.  There have also been other declines in range and abundance of this animal in the State.   Their reintroduction will hopefully enable the Zoos SA and Arid Recovery team to learn more about their ecology and threats.

These womas were bred at Adelaide Zoo in 2003, as part of a captive breeding programme. They have been through an intensive quarantine period to ensure that they do not carry unwanted diseases into wild reptiles. Radio transmitters have been surgically placed in the snakes to allow monitoring following the release. The release, on September 22, 2007 saw nine of the snakes join the growing list of Australian native animals thriving within the reserve. With five of the snakes undergoing a ‘hard release’ and the other four a ‘soft release’, it provides a perfect opportunity to compare release methods for these pythons. 

Established in 1997, Arid Recovery reserve is centered around a 60km² fenced reserve from which all feral cats, rabbits and foxes have been eradicated. This has provided an area of complete protection into which four species of locally extinct mammals – the greater stick nest rat, burrowing bettong, greater bilby, and western barred bandicoot – have been successfully reintroduced. The Arid Recovery Project is a partnership of BHP Billiton Olympic Dam, the South Australian Department for Environment & Heritage, the University of Adelaide and the community group Friends of Arid Recovery.

The release and monitoring program is a milestone in the history of the Arid Recovery Project because it will be the first time a native predator is reintroduced into the reserve.  Womas are a natural predator of reintroduced greater bilbies Macrotis lagotis sagitta and possibly burrowing bettongs Bettongia lesueur and their introduction to Arid Recovery is aimed to both assist woma conservation and help regulate reintroduced mammal populations to more natural levels. However, unlike foxes and cats, they are unlikely to threaten any of the reintroduced mammals because they only feed occasionally.

The woma release and a community education program around it are co-sponsored by Zoos SA and BHP Billiton Olympic Dam.

Further donations towards in situ reptile conservation are raised through Adelaide Zoo’s Boileau Behind the Scenes Tours. Come and visit our reptiles on the “Rapt in Reptiles” tour, learn more about them directly from their keepers, and personally contribute towards reptile conservation.

This update is from John Read of Arid Zone Recovery, received Monday October 8, 2007.

Approximately twelve people, including Adelaide University students, have been involved with the radio-tracking of the woma pythons since their release on September 23, 2007.

Four of the womas have not emerged from their original holes, three have emerged (left tracks near their burrow) on 1-3 occasions, one has moved twice and one has moved three times (I have seen it active the last two mornings at 9:30-10:45ish). They are using a range of bilby, goanna and mouse holes, and two are sheltering under dune canegrass where no burrows are visible (but presumably exist!). None have moved further than 25m from their release point…”

Jennifer Hayes, a Zoowatch volunteer and member of the Friends of Arid Recovery will be radio-tracking the womas over the next fortnight.

This update is from Adam Bester of Arid Recovery, received Friday October 26, 2007.

“Well I thought I should all make you aware of a recent event regarding the womas. Yesterday I went out tracking and found woma 92 on the move (in the hottest part of the day mind you) and found it approximately 150 m from it’s hole from the night before.  It was located under a half dead horse-mulga.  It moved when I approached so I stood still to take a GPS reading.  Whilst doing this I noticed some other movement under the tree and, low and behold it was a mulga snake.  It would have been the same size as the woma and they were both moving so I backed off for fear that the mulga might strike out at the woma.  I noticed my GPS wasn’t working properly so I went back to the car to get more batteries.  By the time I came back to get a reading, the mulga snake had gone but the woma was still there.” 

“One of our volunteers went out today to track 92, and tracked it straight to the same mulga snake (presume it was the same one as it was under the same tree).  It didn’t move so got Helen to go out and have a look.  After she got the mulga snake to move she noticed that it was quiet large and bulging and appeared to have the tracking device inside it!!!.  A bummer but still quite interesting.  I spoke to Greg Johnston and we agreed that we would track the mulga snake each day as this is interesting stuff and wait until the transmitter comes out the other end!! 92 was one of the males”

This update is from Adam Bester of Arid Recovery, received Friday November 16, 2007.

“Hi all.  Well, well, well - it appears as though the mulga snakes aren’t too happy with a new snake on their turf.  Helen was out yesterday tracking the womas and came across 98 (who escaped from the pen on Tues).  They tracked it to near the burrow it used the previous day and saw the woma 5m from its burrow.  They then saw a 2m mulga right near it, and they were practically on top of each.  The woma moved when first sighted, then the mulga struck 6 or 7 times and attempted to drag it under a bush.  The mulga then attempted to eat it.  It had some trouble doing this so it then dragged it out into the open again and at this time the woma was very much dead (I didn't realise the venom would be this quick - perhaps the mulga had bitten it earlier on?).  The mulga was then beginning to get a bit cranky with Helen and Chris so they decided to leave it be.  Please find attached some cool photos. The other bad news is that 98 was a female.

Additionally Helen and Chris also saw a smaller mulga go down a burrow that 97 was in last week and the woma hasn't moved since.  We will keep you updated with this one.  Lets hope it’s not three to the mulgas!!!!

However, some good news is that all remaining womas have now moved burrows, been sighted or have had tracks in front of their burrows.  Only 96 is left in the pen.”

This update is from John Read of Arid Recovery, received Tuesday January 15, 2008.

“At least three, possibly up to eight of the womas have been killed and either eaten, regurgitated or left to die by mulga snakes (at least two different mulga snakes involved). Three of the womas that have been retrieved, dead or alive, have demonstrated through faeces or weight gains that they fed successfully prior to their demise.

I had assumed (incorrectly!) that the 5-year-old released womas would have some degree of tolerance to mulga snake venom, and indeed may have been predators of these snakes.

It is too early to speculate on lessons learned and I am still finalising details of several records that will help clarify the last movements of the deceased womas.

As of today we have #95 still happily basking outside its hole, and #99 AWOL for over one month, with all others deceased.”

This update has been taken from the media article published in the Roxby Downs Sun, January 17, 2008, entitled Woma python numbers drop.

“Of the nine pythons released last year, most have fallen prey to mulga snakes. Now there is one python remaining and one unaccounted for, a result that has been described as “disappointing but interesting at the same time”.

“It was always a trial release, no-one knew what would happen, now that we do we  know we’re going to have to change tact a little bit and try a different approach” said John Read (spokesperson for Arid Zone Recovery).

“This will lead to more studies of wild womas and looking at the numbers of mulgas within the reserve, and we know there are at least three large mulgas in the area where we released the womas”.

Mr Read said the project has also given researchers the chance to study the movements and habits of mulgas, thanks to the many volunteers who checked on the womas every day.

“Most people assume that womas would be immune to mulga venom, so if nothing else we have proven this is not the case. We even found that one of the mulga snakes was the same size as the woma, which is bizarre because I would have expected a really large woma to eat the mulga”.

Arid Recovery will continue to track the remaining woma and hopes to embark on a new different approach to the research over the next few years.

This update is from John Read of Arid Recovery, received January 24, 2008.

“I have just conducted another brief radio interview about the womas with ABC News-Radio in Sydney. I took the opportunity to explain about Arid Recovery and stressed that this trial release was not a failure but a learning experience (for us not the snakes).”

“For the record, our last survivor, stoic #95, was found dead yesterday, showing symptoms consistent with snake attack. I went flying on Saturday and was unable to locate #99 which has been missing for months. I intend having another scout around on the ground for this beast before concluding the field component of the trial with more questions than when we started.”

It is likely that our experience will lead to studies of venom immunity in womas, and also an evaluation of the relationship between womas and mulga snakes where they occur in sympatry. These are unlikely to be conducted by Arid Recovery; rather NRM, Zoos SA etc. would be the likely proponents. Maybe large wild womas can either defend themselves or avoid mulga attack, and may even lower mulga densities through predation to allow their juveniles to recruit. I would support the ‘re-batterying’ and reuse of our woma transmitters (on a loan basis) for such wild studies, given that they should assist in woma conservation and possibly another reintroduction or relocation plan for Arid Recovery.”