Forest Service survey

Press, 1 March 1984, Page 18

Forest Service survey

Do not be surprised to see large snails marked with little white dots wandering around the Mokihinui State Forest area on the West Coast, says the Forest Service. They are not a new sub-species of the giant land snail fobnd in the area, but are part of a survey by the Forest Service.

Forester Dave Bishop from Westport, assisted by Nick Graham Higgs and Richard Wilkinson, have begun walking through the forest at night armed with torches, spotlights and a bottle of the white-out paint used to correct typewriting errors. By marking the shells of the snails they will be able to determine the population of the two sub-species of giant land snail, the powelliphanta lignaria rotella and the powelliphanta lignaria johnstoni, which are described as endangered species. “It’s been very promising,” said Mr Bishop. “We look in areas of logged forest, and work along taped lines set in a grid pattern in

the bush, looking on each side. In half an hour we recorded seven snails. In daylight you would have seen only one.”

Concern about the proposed forest operations in the Buller region, and the effect on the survival of the snails, prompted the survey, which began in January. By recording the distribution and population of the land snails, the Forest Service hopes to learn how many there are left, if they are an endangered species, and, if so, why. Whether they do return to areas of forest which have been converted to exotic forests will affect the decision on areas used in the future, the service says. Until now surveys by both the Forest Service and the Wildlife Service have been conducted by going into an area and counting shells. Mr Bishop said that this determined the extent of the snails’ habitat, but it not indicate how many snails were actually left. Principal Forester Curt Gleason

explained why this was so. “Population counts are difficult things to do — we do not know how old the shells are, how long they have been there, how long it takes them to deteriorate or under what conditions. Then there are natural fluctuations in animal mortality rates which must be taken into account,” he said.

Mr Gleason said that there are many more questions to be answered concerning the habits of the snails — their movement patterns, genetic characteristics and impact of forest production — before a full understanding could be reached.

A review of the survey will be made this month to decide what course the programme should take. So far the indications of snails returning to logged areas and living in different types of forest are encouraging, the Forest Service says.