Green snags and ‘grunts’ to reduce pig population

A University of Queensland (UQ) PhD student is using green snags and simulated pig noises to keep feral pigs from tearing up the rainforest and recently spent a few days staying at the ARF’s Daintree Community Conservation office to further his research with fruitful results.

Andrew Bengsen, from Mossman, is part of a UQ team working on a four-year-project to control pigs in tropical rainforests and his green, sausage-shaped baits target wild pigs but are not eaten by most of the other 300 odd animals that inhabit the rainforest.

“We are trying to make poisoning an option for feral pig control as trapping only has a limited, localised effect due to the pigs rapid reproduction,” Mr Bengsen said.

”The baits are green cylinders that weigh about 250 grams, are 10 cms long and made of fishmeal and grains. Having animal and vegetable products in it, deters specialist feeders such as wallabies and other strict herbivores. Pigs are happy to eat anything,” he said.

The baits are coloured green to deter animals that use colours to identify food and are buried 10 centimetres below the forest floor so only pigs can smell and dig them up, while most other animals don't.

“Small animals like rodents will have a nibble on the outside of the bait and they'll be full, but the toxic core would be put inside the centre of the bait so the animal has to eat the whole bait or tunnel right into it in order to be poisonous.”

Mr Bengsen said there were still eight species that ate the baits but was considering adding chemical repellents for birds and other animals and using sounds of pigs feeding to deter rodents and bandicoots. “There is anecdotal evidence that some of these animals will avoid areas where pigs are actively feeding. Pigs also use information from other pigs to locate food so they'll follow trails and sounds from other pigs. We're hoping that these sounds of happy pigs feeding will draw other pigs into the area and enhance their bait encounter rate.”

Mr Bengsen has now completed the fieldwork for this stage of research, and is analysing the results. The next stage research will investigate seasonal patterns of nutritional stress in pigs and non-target animals, and the influences this may have on bait consumption. It is hoped that this information can be used with knowledge of feral pig movements and population dynamics to identify optimal seasonal conditions for baiting.

Mr Bengsen is based with the Davies laboratory in CSIRO's Townsville office. His project group is led by Iain Gordon for UQ, the IACRC and CSIRO's Division of Sustainable Ecosystems.

 Invasive Animals CRC newsletter Nov 2007 (PDF - 434kb)