We conducted a trial of the Judas technique as a tool to eradicate feral pigs (Sus scrofa) from a reserve in Santa Clara County, California, USA. A hog-wire fence was constructed around approximately 1000 ha of the reserve, effectively creating an inland island. Three pigs were captured, radio-collared, and released as Judas pigs in an effort to eradicate a remnant population of an estimated 40 pigs. Trap success was affected by mast crop size and timing and by male dominance at bait piles. Using telemetry, we located pigs in less than 1 hr, compared with >4.1 hr without telemetry. Though our sample size was small, our results suggested that females made the best Judas pigs. We roughly estimated the number of Judas pigs required for the project by estimating home range sizes and dividing by the observed usable habitat within the enclosure. The Judas technique has been used with goats as a single method for eradication. It also works well in less social animals, such as pigs, but we recommend it as an adjunct to other proven eradication methods
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