Sometimes things just don’t work out as planned

A couple of years ago, Terrestrial Ecosystems undertook a fauna relocation job south-east of Port Hedland. It was large project area and our task was to catch all the Mulgara (Dasycerus blythi) that were present and relocate them to an area specified by the client before the vegetation was cleared.

Four staff worked hard each morning clearing up to 1,600 aluminium box traps of fauna within 4hrs of sunrise. Traps were either rebaited or collected and moved into other areas scheduled for vegetation clearing. Traps were spaced in grids 25-30m apart. We caught more than 1,500 animals including Mulgara, who at that stage were listed as a threatened species under the EPBC and the WA Wildlife Conservation Acts. Radio-transmitter collars were fitted to the Mulgara and they were released into suitable habitat at the client specified location. The next day they were located and had not moved very far, so we thought they may stay in the general area.

The intervals for radio-tracking the Mulgara were determined by the client, however, we used every opportunity we were in the area to find their location as we anticipated the Mulgara may move outside of the range of the radio-transmitter quite quickly.

Two weeks later we returned to locate our Mulgara. They had not moved very far and were relatively easy to locate. As it was during the day when we were locating animals all Mulgara were in burrows. If we were working in the area and planned to check the location again the next day we would mark the burrow entrances to ascertain if the Mulgara had left the burrow that night and returned. In most circumstances there was evidence that the animals were moving in an out of the burrows, however, we couldn’t always check as we weren’t always there the next morning.

On a return trip approximately four weeks later, we arrived at the site we had relocated more than 1,500 animals to discover that the area had been cleared of all vegetation and topsoil by a contractor who was not working for our client, and our client had no knowledge that the area was to be cleared.

Plate 1 and 2: Single aluminium box trap and line of traps in the spinifex

One of our tracked Mulgara was moving around quite a lot but we managed to find it every couple of weeks and it eventually settled into a burrow under some shrubs and spinifex and stayed there for about six weeks. Each time we checked the signal was coming from the same hole but in a different location within the hole so we were reasonably confident that the Mulgara wasn’t dead. After about six weeks of being found in the same locality we decided to dig it out to confirm that the transmitter was attached to the Mulgara, and the animal was alive. We slowly and progressively excavated the burrow making sure that we would not harm the Mulgara or any other animal in the burrow. To our surprise, there was no Mulgara, but a Woma Python (Aspidites ramsayi) present with a bulge in the abdominal area. The beeping of the transmitter was coming from the woma, so it seemed that the woma had caught and eaten the Mulgara, possibly while it was in the burrow.

Although it might be expected that womas would eat Mulgara if the opportunity arose, this is the first record we can find of it actually occurring.

It seems like these relocated fauna were never destined to survive with a combination of land clearing, habitat fragmentation and predation impacting on them.

When doing fauna relocation programs, one has to wonder how often fauna are relocated to an area that has subsequently been cleared and the relocation program has been thwarted. In addition to this Pilbara example, we have seen this in the Perth metropolitan area where we relocated Southern Brown Bandicoots to a specified area, only to catch them two years later and move them again due to more vegetation clearing for a housing development (Thompson and Thompson 2016).

Our experiences with failed relocation programs are not isolated events. It is our belief that industry and environmental consultants would welcome clear fauna relocation guidelines that are based on good science for before and during vegetation-clearing programs. Of utmost importance, and as discussed more thoroughly by Menkhorst et al. (2016) and Thompson and Thompson (2016), is the need to monitor and assess the overall outcomes of these programs to determine whether they are a success or not.

Do you have any experiences of fauna relocation programs that have been a resounding success or miserable failure?

References (can be supplied on request)

Menkhorst, P., N. Clemann, and J. Sumner. 2016. Fauna rescue programs highlight unresolved scientific, ethical and animal welfare issues. Pacific Conservation Biology. DOI: http://dx.doi.org/10.1071/PC16007

Thompson, S. A., and G. G. Thompson. 2016. Response to ‘Fauna-rescue programs highlight unresolved scientific, ethical and animal welfare issues’ by Menkhorst et al. Pacific Conservation Biology. DOI: http://dx.doi.org/10.1071/PC16015

Images – top: Mulgara with radio-transmitter collar being released (Edward Swinhoe); bottom: Woma Python that ate the Mulgara