First catch your koala! Use of a trap to capture koalas Phascolarctos cinereus for ecological studies
Hasegawa, M & Carrick, FN 1995, Australian Zoologist, vol. 30, no. 1, pp. 68-70.
The trial of a new design of trap to capture koalas was detailed in this article. The trap stops a koala that has descended a tree from re-climbing the tree and keeps the animal in an enclosure until a field worker can recover it. The experiment serves as a proof of concept and efficacy, capturing nine koalas with a mean capture length of 1.9 days.
The trap uses two pieces of galvanized corrugated steel, one as a fence around the base of the tree and the other as a temporary collar around the tree trunk. Once the koala descends the tree, the collar stops it from climbing back up. The fencing stops the koala from leaving the tree base until a field worker can capture it and transfer it to a transport cage. Using the trap, larger trees were more effective at trapping koalas at their base as it was more difficult for koalas to climb over the collar, and females with back young were the easiest group to capture as a result of their decreased mobility. In one instance, two koalas were captured in the same trap as they had been in the same tree.
This method provides several advantages over the current capturing method, which involves a person in safety gear climbing the tree containing the koala, placing a noose around its neck and waving a flag over its head to encourage it to climb down the tree, while another person waits at the bottom of the tree to capture the animal. The new trapping method described eliminates the risk of falling from the tree, requires only one person to set up, possibly stresses the koalas less, and can be used in large, unclimbable trees. The downsides to using the trialled trapping method include its restricted use in isolated trees, as otherwise the koalas could climb across branches to descend the other tree, and taking much longer due to having to wait for the koala to climb down the tree of its own volition rather than encouraging it down. This drawback may also have implications for the welfare of the target koala, as on one occasion the trap had to be removed after a koala remained in the collared tree for seven days in a potentially stressed state.
The use of the trialled trap has immense practical benefit for the easy and safe capturing of koalas. This is useful for both research and relocation purposes, both of which are important for the species’ conservation.
Summarised by Laura Wait
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