Wanted: the ideal animal trap

Press, 26 September 1980, Page 13

Wanted: the ideal animal trap

By

GARRY ARTHUR

If.you happen to come up with a better design of opossum trap, 15,000 trappers will beat a 'path to your door. But it will have to be a good one. It will have to be as good as the old-fashioned gin trap (the ordinary rabbit trap) at catching opossums, very poor at catching kiwis and wekas,

cheap to buy, light to carry, small in size, easy to set, incapable of causing suffering, and preferably an instant killer that does no damage to the valuable opossum fur.

The gin trap meets some of these requirements — light, cheap, easily set, and very efficient -—but it does cause pain and suffering because it catches the animal by the leg, and it does catch native ground birds. New designs are coming up all the time, and as they appear, the Forest Research Institute eval-

uates them both in the laboratory and in the field. So far it has found no trap that meets all those requirements, and indeed none that does the job better — from both the fur-trade and . opossum control point of view — than the old fashioned much-maligned gin trap.

Dr Jim Colman, the institute’s scientist in charge of opossum research, says the trap evaluation programme was prompted by the S.P.C.A.’s attempt last year to have a private member’s bill . pissed outlawing gin traps as inhumane, and also the Wild Life Service’s, concern about tire trapping of kiwis and wekas.

Trappers’ requirements are also being taken into account. The opossum fur trade has grown rapidly in

recent years, earning $23 million in export receipts last year. Les Batcheler, the Forest Service’s scientific represenatative on the technical advisory committee on animal pests, is convinced that every trapper would welcome a good kill trap. Opossums would be dead when the trapper returned to empty the traps and could be skinned at once. When he has to kill the trapped opossums, he has to leave the bodies for at least eight hours to get cold before they can be skinned.

“I think most trappers would be prepared to lose 10 per cent of their present catch for the convenience of not havirig to work'their line again,” Mr Batcheler says. The 10 traps being tested by Bruce Warburton of the institute’s staff fall into two categories — leghold traps like the gin trap, and killer traps. Four varieties of leghold trap have steel jaws which snap shut on the opossum’s leg. These gins are favoured by trappers because they are light, cheap, efficient, and damage only the fur around the leg. A trapper can carry up to 40 of the old rabbit traps and even more of the smaller Mont-

gomery and Victor gin traps. All three were found to do similar damage to the opossum’s leg muscle and bone. Another, the Victor Stopless, has an. extra spring lock to hold the leg tight.

Two other leg-hold traps — the Aringa and the Humane - — grab the leg with a noose of cord or wire spring. It was found that opossums could often pull their feet free, or chew through the cord and escape.

Kill traps tested by Mr Warburton include the American Bigelow. It has two steel rings which snap together when the opossum presses the bait holder with his nose. The rings whack him behind the neck.

It was found to catch only one sixth as many opossums as the gin trap, and 30 per cent of those caught were held around the chest or shoulders, with resultant'fur damage. Even some of those caught around the neck were not killed. Mr Les Broadmore’s Banya trap (illustrated in “The Press” on Tuesday) has a spring-operated steel bar which crushes the animal’s heck. The. scientists say they were" told by ’ a user that one in - every seven opossums caught by the trap was not killed by it. Their tests showed it to be able to catch only 6

per cent of the number caught by the gin trap. “But it’s - just as good as the gin at catching wekas,” Bruce Warburton adds. The Conibear 220 is another American trap, originally designed to catch beavers under water. A large pair of pliers has to be carried for setting the spring on the square steel frame, and it was found to take twice as long as the gin trap to set. It caught nearly two-thirds as many opossums as the gin trap, but about 30 per

cent of those were still alive. A tenth trap, the Kaki, has not_been tested yet. It is a 12-inch tube of plastic piping .with another tube inside it. Two holes ■in the side are lined tip, and when the opossum puts . his head through, a trigger releases the inner tube which _ shoots upwards, strangling the animal, It costs $22, and Mr Warbur-

ton says that although it is light it is too bulky for commercial use. So far, Mr Warburton has yet to. find a trap more efficient than the old rabbit trap,- Dr Coleman says. The Victor is equally efficient but it is also a gin-type trap. He has yet to find a trap that will

catch only opossums. All kinds were found to catqh ground birds. - Gin traps with straight jaws were found to cause as many injuries as the old rabbit trap with serrated jaws. “And the socalled humane traps commonly leave the animal in agony — in distress, choking all night,” Dr Coleman says. ?. -;

The gin .trap is banned in Britain because it is considered cruel, but Dr Coleman says that if it is outlawed here it would slow down pest control as' well as commercial "harvesting” of opossum furs* which ate "important export earners. Indeed, if it. were not for the .value- of the fun trade, Mr Batcheler says he would advocate the use of 1080 poison for the ef- ; fective control of the opossum pest. In Tasmania, the. only other place where opossums are wanted for thein skins, rifles are used to hunt them. Mr Batchelen

says this :. is very inefficient. Shooting; oposslims has a very low suecess rate in the bush, where -they are hard to see..:;Thanks largely .. to concern. expressed by the conserration movement* people all over tLe world are experimenting with new animal trap designs. In Britain alone there are

said to be 90 existing designs, and in Christchurch at least two people are working on new designs. One is a plastics manufacturer trying to produce a trap to catch live opossums for opossum farmers.

Mr Batcheler sees great difficulties in the way of a trap 'which will meet all the criteria, especially the high catch rate, ** elimination of suffering, and lack of danger to .- non-target species. - .. -, “On behavioural grounds,” he says, “it is very tricky to design a trap which will 2 do these things.”