Noxious Animal Control Debated

Press, Volume CIII, Issue 30390, 14 March 1964, Page 6

Noxious Animal Control Debated

With present techniques it was possible to get deer down to low levels where there was a good recovery of vegetation, Mr J. T. Holloway, officer in charge of the forest and range experiment station of the Forest Service in North Canterbury, said during a panel discussion this week on the subject of whether noxious animals in New Zealand should be exterminated or tolerated.

The discussion, organised by the Canterbury section of the New Zealand Institute of Agricultural Science, was limited to deer, thar and chamois.

But with better conditions for browsing if the pressure on the animals was taken off at this stage their numbers would increase again, said Mr Holloway. “We do not know how to keep them down once we get them down. Mr Holloway cited the case of an area where numbers had been reduced to the point where good hunters were taking only one a week. Hunting had then been stopped for three years. For the first two years nothing had happened then the animals had appeared all over the place again. ■ He suggested that the introduction of such unacceptable diseases as foot-and-mouth and scab would get rid of these animals, but he said that it was possible to use a combination of 1080, the most humane poison that there was in spite of what was said about it, and shooting, so that animals were driven into areas and planes could then drop poison over these areas. The speaker agreed with Dr. B. Stonehouse, reader in zoology at Canterbury University, that there was a need for trained biologists in the field but the difficulty he suggested was to get people who could work in this country. There was at present one for about every five million acres and not yet one for every species. Dr. Stonehouse felt it was not practicably possible to achieve extermination of an animal, particularly in a country like New Zealand, a lot of which was as yet untrodden by man and would remain so for a long time to come. Since 1961, he said that one million animals had been shot, yet, as Mr Holloway had noted, every species was in danger of spreading or moving into a new area. A terrific effort had gone into keeping animals where they were and it underlined the problem. “I think that we can conclude that present methods are no more than holding the fort,” he added. Research Looking to what further could be done. Dr, Stonehouse, referring to Russian and American work, said that techniques of control could be improved if trained biologists were put into the field alongside the shooters to obtain information such as the reproductive capacity of species, the distances that they travelled and the degree of uniformity in a population. This was an approach that Dr. Stonehouse said he pinned faith on otherwise they would be “knee deep” in noxious animals before they knew where they were. Mr L. W. McCaskill, director of the Tussock Grasslands and Mountain Lands Institute, who is well-known for his strong views on the noxious animal problem, said that in the pest no animal ecology

had been available in the university and most of the animal ecologists had come from overseas and New Zealand conditions were so different from the environment in which they had been trained that they had made ghastly mistakes.

He wondered whether enough “tough guys” would take the course in animal ecology in the university but be suggested that through the forest and range experiment station and work of the Forest Service they were on the road to obtaining some of the answers needed to achieve economical and efficient control of noxious animals. Dr Stonehouse said that he was trying to get down on paper a programme to train about 20 research students in the next five years to provide the men that Mr Holloway needed. Noxious Defining a noxious animal, Mr McCaskill said the basic aim of national parks and scenic reserves was to preserve these areas as near as possible to their natural state and if the park concept was accepted it meant that every animal in the park must be considered noxious. In relation to production he suggested animate must be considered noxious where they interfered with timber production in native or exotic forests, with sheep and cattle production and where they interfered with establishment of shelter and induced erosion. Mr A. S. D. Evans, an engineer with the South Canterbury Catchment Board who is president of the South Canterbury branch of the New Zealand Deerstalkers’ Association but who was talking as a private shooter, suggested that animate being discussed were not noxious if they were kept below the level where they interfered, and Mr Holloway agreed with this view saying that they were not noxious until they interfered with a human interest, but they could be noxious to people with one sort of interest yet not noxious to others. Mr Holloway said the red deer was probably the greatest problem because it was more widespread, in greater numbers and had had a longer impact on the country. The Virginian deer was in two small areas. In one of these, the head of Lake Wakatipu, it had started to spead in the last 10 years apparently because the red deer had opened up the forest. There was a worry here about disease as the Vigtinaan deer was lousy with such diseases as false hydatids and lung worm and it intermingled with sheep and cattle and it was not known whether

these diseases were transferable. Fallow deer were a worry to some farmers with their close grazing habit® and in the southern part of the island were responsible for doubling the cost of new forest establishment. Mr Holloway suggested that the spread of the fallow deer out of the Wakatipu area might have been prevented by a barrier of badly depleted country, but with' run plans and improvement schemes he had a horrible feeling that the plug might be taken out In the last 10 years the thar had started to move fast and was now in the headwaters of the Hokitika and male animals were on the fringes of Molesworth. The female thar ate as much as a ewe, he said, and the bull thar which was three times as big ate about three times as much as a Merino ram. It was bad from a vegetation point of view in that it concentrated on one area of grass or shrub before moving on to another. Chamois now extended from Fiordland to Blenheim and they were where vegetation was most vulnerable and at the highest altitudes. They were in area® where the rank and file shooter would not penetrate. Mr Halloway said that top priority areas in the South Island for Forest Service noxious animal control programmes were in the Waimakariri and Wairau rivers where there was a lot of class 8 country and ratepayers were paying for protection works lower down. Discussing the role of the private shooter, Mr Evans agreed that his penetration was limited by access and limited time at the week-ends but . suggested that he was taking some of the burden off the Forest Service men and he thought that the day would come when private shooters would be able to control a certain animal in a certain area.

Mr Evans said that he felt it would be the worst possible thing if vension was devalued. He said that the red deer had been increasing in the Landsborough, but with high prices of vension, shooters had gone in by jet boat and aeroplanes. If this had not happened the Forest Service would have had to go in and thereby split its forces. Uncertain Mr Holloway expressed som e uncertainty about the value of the work of the private and professional meat shooter. He said that studies in one area suggested that deer, like human beings, went downhill as they got older and that professional deer meat killing operations might be cleaning out the older deer and making it better for the younger deer further up. He also feared that if the trade in vension became too entrenched there might be strong pressures to keep it going.

Mr McCaskill said that he was right behind devaluation; Shooting of deer in tough country wag dependent on skilled men but today it was too easy for a man to shoot five or six deer and dear £5O a week.

He also expressed concern at the conditions under which deer meat for export was being produced. He said that to keep flies off the meat shooters had been spraying it with the same sort of containers that were used round the home to control flies and it frightened him lest D.D.T. residues should be found in New Zealand vension overseas. He knew that the Mini-

ster of Agriculture was also concerned and from the Haast to Jackson Bay new buildings with fly screen doors had sprung up to hold the meat pending its dispatch. He felt that the risks involved in the export of vension for the relatively small income earned were too great. To Dr. Stonehouse Mr Holloway said he believed in time in certain areas it might be possible to leave control to private shooters and to treat the game as a natural resource, but this would be in populous areas and he suggested that this might be a long way off in the South Island with its smaller population and greater proportion of higher country. He said that quite a lot of money had been spent in extending the access of the private shooter and he suggested that from conservative calculations he had made the cost of a game management policy would be of the order of £5 an animal. Mr Evans suggested that the danger might be that the game resources would be under the control of the runholder for export. It had been reported that the net profit from a red deer was

greater than from a prime bullock. The answer to this was devaluation, said Mr McCaskill. To a suggestion from the chairman. Dr. M. M. Burns, that these animals should be run on the higher country rather than sheep and cattle, Mr McCaskill said that there might be some case for this from a production angle only, but he would be concerned at the effect on the country as they could not be controlled and therefore the vegetation could not be controlled. Mr McCaskill maintained that no control of deer had been achieved in New Zealand by private shooters. Control was a reduction of numbers to the extent that vegetation was able to recover and it did not seem to be realised what small numbers of animals could prevent this recovery. There could only be control when the original palatables were able to grow and the forest was restored to its original condition. Unless this concept was realised vast areas of New Zealand forest would die out.

Mr Holloway said that he knew of no major forest areas

in the South Island or any major area of the back country where control had been achieved by private shooters. Answering Dr. Bums who hinted that there were better poisons than 1080 and asked why should they not be used, Mr McCaskill said that he was a strong adovocate of the use of tetramine under strict control because it had frightening mammalian toxicity. He said that by putting a pellet of the material close to the new plantings it would save the Forest Service the doubling of cost of plantings in the southern part of the island, for the young tree would take up the poison and animals that came along to browse on them would die. Placing of pellets alongside palatables in natural forests would have a similar effect and in no time they would be on the way to extermination, he said. [Lincoln College is the only-institution in New Zealand where there is a full course in ecology. It has been taught for at least three years with on average about six taking the course.]