The ‘Judas’ Pig Technique: a Method that Could Enhance Control Programmes against Feral Pigs, Sus scrofa

Abstract

The successful ‘Judas’ goat technique has been adapted for use with feral pigs. The ‘Judas’ goat technique involves releasing radio-collared goats into a control area and, after a sufficient period to allow them to join other goats, tracking them down and culling the other individuals associated with them. Trials with the technique on feral pigs in Namadgi National Park, ACT, indicated that it worked best with sows captured in the same area. Each of these sows established contact with 1–8 other pigs in the area within 1–7 days of release and was located with at least one other pig on 67–100% of occasions. In contrast, sows and boars from outside the study area took longer to come into contact with ‘local’ pigs and associated with them much less frequently. A subsequent control exercise in Namadgi, using ‘Judas’ pigs to indicate where to lay warfarin baits from a helicopter, resulted in a 75% reduction in the low-density population still present after a larger control exercise two years earlier. Since then, the technique has been used to eradicate a small colony of feral pigs in central Australia and is proving successful for control of feral pigs and other ungulates in other parts of Australia and New Zealand.

Feral swine damage and damage management in forested ecosystems

“…Similarly, the technique was found useful at reducing time spent locating feral swine when integrated with other methods, such as ground and aerial shooting, trapping, and hunting with dogs in Santa Clara County, California (Wilcox et al, 2004). Sows trapped locally have been found to make superlative Judas pigs (McIlroy and Gifford, 1997;Wilcox et al, 2004).…”

“…On large tracts of land involving discontinuous populations, Judas pigs may provide information on where to target feral swine control efforts (McIlroy and Gifford, 2005). For example, in the Namadgi National Park, Australian Capital Territory, the Judas pig technique has been used successfully to determine where to distribute toxic baits (McIlroy and Gifford, 1997). Similarly, the technique was found useful at reducing time spent locating feral swine when integrated with other methods, such as ground and aerial shooting, trapping, and hunting with dogs in Santa Clara County, California (Wilcox et al, 2004).…”

Effects of simulated removal activities on movements and space use of feral swine

“…The BJudas^hog technique, or using feral swine with very high frequency (VHF) or Global Positioning System (GPS) collars to locate other feral swine, has been used with some success to eradicate feral swine from islands, national parks, and fenced areas (McIlroy and Gifford 1997;McCann and Garcelon 2008;Parkes et al 2010). Although there are no toxicants currently registered by the US Environmental Protection Agency for use on feral swine in the USA, researchers in New Zealand have recently registered a bait matrix that includes sodium nitrite and is lethal to feral swine (Shapiro et al 2015).…”

Attractants for wild pigs: current use, availability, needs, and future potential

“…Intra-sounder dynamics are highly complex, suggesting that wild pigs evolved as a communal species and therefore seek conspecifics similar to other communal species (Gabor et al 1999;Witmer et al 2014). For instance, solo females contacted other resident wild pigs in a nearby area within 1-7 days of release (McIlroy and Gifford 1997). Similarly, females with young rejoined their sounders only 9 days after farrowing (Jensen 1986).…”