Radios and Judas goats

Forest and Bird, Volume 23, Issue 1, 1 February 1992, Page 3

Radios and Judas goats

LIFE WILL NEVER be the same for feral goats who will now have to be on guard for the Judas in their midst. The Department of Conservation has recently completed a successful trial to locate and eradicate feral goats using radio transmitters. By fitting transmitters to a small number of goats DoC staff can rely on the goats’ gregarious instincts to lead them to larger elusive herds. Because of this tendency to "betray" their companions the radio-carrying goats are known as Judas goats. Feral goats range across about 16 percent of New Zealand and are among the most destructive pests on conservation lands. They cause huge damage to native vegetation because they browse on a wide range of plants and can induce erosion and the siltation of streams by stripping vegetation from some sites. Goats threaten a number of palatable species with limited distributions such as Celmisia adamsii on the Coromandel Peninsula. They also compete with native foliage-eating birds such as the kereru and kokako. The use of radio transmitters to track goats has been used successfully overseas in Hawaii and South Australia. It was first used in New Zealand in the Arthur’s Pass area using domestic goats but failed when the goats died. In DoC’s recent trial, in the mountains bordering Mount Aspiring National Park, six goats were first captured by hunters leaping from helicopters and wrestling them to the ground. Each of the goats was fitted with a transmitter housed in a metal tube attached to a bright red collar. These Judas goats were then taken by helicopter to strategic points around the trial

area and their movements tracked by the radio signals. Sixty-one goats were located and shot by helicop-ter-borne hunters following the radio signals. Chris Main, the senior conservation officer in charge of wild animal management work in Otago, considers that the trial was very successful and a costeffective way of achieving control especially in lowdensity areas where herds are difficult to locate on foot. "In the park buffer zone we’re always going to have to be vigilant because there seems to be a steady influx of goats

from adjacent areas. Without the control work the goats would become established in the national park and go right through it. They are very destructive." DoC is continuing the radio tagging programme in Otago to complement foot hunting and regular helicopter hunting until feral goats are either eradicated or reduced to very low numbers. DoC would like to extend the programme to other conservancies but the main constraint is the high initial cost of the equipment.