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Snappy New Possum Trap Effective And Humane

The Bulldog trap with one of its inventors, Bruce Warburton of Landcare Research

A scientist and two engineers have joined forces to invent a unique, highly effective possum kill trap, the "Bulldog"!. It is compact, lightweight, robust and suitable for commercial operations. It is very humane, which helps possum trappers make the most of new animal welfare legislation.

Possums damage native forests, spread bovine Tb among cattle and deer, and eat the eggs and chicks of native birds; and for those reasons, possums are trapped nationwide. The Animal Welfare Act 1999 enables trappers to leave kill traps unchecked indefinitely, though leg traps must still be checked daily. Until now, trappers have had to deal with the uneasy trade-off of carrying bulky or heavy kill traps, or carrying a larger number of the more compact leg traps, with the associated cost of having to check them daily.

Landcare Research pest impacts team leader Bruce Warburton, Lincoln University engineering lecturer Ian Domigan and retired engineer John Hewett have created the "Bulldog" kill trap, which looks somewhat like an oversized bulldog clip. Possums are caught when they put their heads into the trap to reach the bait. Like a bulldog clip, the Bulldog trap has strong clamping force which belies its size. At 25 centimetres long and weighing in at about 500 grams, the Bulldog is less than a third of the size of the Timms kill traps (another NZ made kill trap), but the Bulldog's jaws have a clamping force of about 20 kilograms.

Bruce Warburton of Landcare Research says that pen trials of the Bulldog trap have shown that there is no escape. The traps are very humane. "The Bulldog trap easily satisfies the National Animal Welfare Advisory's draft guidelines" says Mr Warburton. "The possums die very quickly".

"Pest control contractors who have tested the Bulldog trap have been very impressed with its performance. Trappers will be able to carry 30 to 40 Bulldog traps at a time, compared with about eight Timms traps".

Mr Warburton has worked with traps for more than 20 years, and says this one is unique. "It is very simple, with very few moving parts. And it's the only trap I know of that is not powered by a coil spring. Instead it works by levering the folded spring steel apart, with the trap snapping shut when a possum investigates the lure".

Mr Warburton says the Bulldog traps pose less risk to non-target species such as kiwi and weka than many other traps. "That's because the Bulldog works just as well above ground in trees, where flightless birds can't get at them".

Mr Warburton says the Bulldog traps could make quite a financial difference to possum trappers. "Their weight and cost are comparable to leg traps. Also, in many areas, ongoing possum control has left quite low possum densities. It makes sense and saves money for trappers in those situations to be able to leave traps for extended periods without checking.

"Because the Bulldog trap is compact, and can be placed in the bush in quite large numbers and checked at the trappers' convenience, it will help trappers to control possums more cost-effectively, and therefore help deal with New Zealand's possum problem".

Landcare Research will be showing the Bulldog trap at the National Agricultural Fieldays at Mystery Creek, 13-16 June. Bruce Warburton will also be presenting seminars on the research that went into developing the Bulldog trap, on Thursday and Friday at the Fieldays.


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