India, Sept. 28 -- Somewhere on Santa Cruz Island off the coast of California, there was a pig that was turned loose again with a radio collar, and its only job is to lead hunters right to its own herd. It might sound fictional, but that's roughly what happened when wildlife managers carried out one of the fastest large-scale animal eradications on record. A team led by researcher John Parkes removed 5,036 feral pigs on the 25,000-hectare island in just 411 days, according to a study published in the journal Biological Conservation. That averages out to about 12 pigs removed per day.

By the mid-1800s, pigs were introduced to Santa Cruz Island, and over more than a century they multiplied and spread to nearly every corner of the island. T...