Walking through a forest on Bawean Island, Indonesia, after a long and frustrating day in the field, Mark Rademaker came face to face one of the world's rarest wild animals, a kind of warty pig.
"Out of the blue there was a fully grown male in front of me, with these big warts and long, white sideburns fanning out from his head," says Rademaker, of the VHL University of Applied Sciences in the Netherlands.
"We looked at each other for what felt like an eternity—perhaps it was only a split second—and he just took off into the bushes. I still like to think about that moment." (See "Exclusive Video: World’s Biggest Pig Revealed.")
What we know about the Bamean warty pig is equally elusive, simply because most scientists aren't interested in studying the genus of animals more popularly known as bacon. Almost all of the world's 17 wild pig species are threatened with extinction, though few have been studied.
Enter Rademaker, whose camera trap pictures have revealed unprecedented images and video of warty pig families foraging, complete with frolicking piglets. The data also provided the first scientific estimate of how many Bawean warty pigs exist in the wild: Fewer than 400, including around 250 adults.
That number means this subspecies of the Javan warty pig could be listed as endangered by the International Union for Conservation of Nature, according to the study, published April 6 in the journal PLOS ONE.
Because the population is so small and isolated, if there's even a minor change to their environment, things "can go wrong very quickly," Rademaker adds.
This Little Piggy
For the study, Rademaker and colleagues set up 20 camera traps throughout protected areas on remote Bawean Island (map), north of Java, in late 2014 and early 2015.
The team didn't even know if the pig even still existed on the 74-square-mile (192-square-kilometer) island, so when they first reviewed the footage, "there was such relief and excitement, and almost dancing on the spot," Rademaker says.
(Less amusing, he adds, were mischievous monkeys that kept pulling the ropes holding their camera traps.)
The camera trap data helped the scientists determine the approximate size of the pigs—about 20 inches (50 centimeters) tall, relatively compact compared with its close relative the Javan warty pig. (See "Picky Pigs Take Washing Certain Foods Seriously.")
The study finally presents "solid evidence" that the Bawean warty pig still roams the island, as well as where it's found, notes Gono Semiadi, a pig expert at the Indonesian Institute of Science who wasn't involved in the study.
"For the past 15 years working with the species, this is the best number of the individuals we can find," he says.
Eating Like a Pig
The omnivorous pigs, which have no natural predators, keep their environment tidy and healthy by eating a wide range of food—including nearly rotten plants—and dispersing seeds in their feces.
But their diverse diet is also getting them into trouble with local people.
Rademaker and colleagues' data show that the pigs spend most of their time in crop-rich community forests, which border the protected areas. The animals often raid the crops, causing damage, and farmers retaliate by killing them.
Rademaker said that working with farmers to reduce run-ins with the pigs is crucial, as is studying more about how hunting is impacting the species. (See "Why We Love—And Loathe—The Humble Pig.")
Another problem is the protected areas on the island aren't well marked, so people are expanding their logging and farming operations further into the refuges, Rademaker says.
"Being an isolated island, we have to conserve the species from declining due to habitat loss," Semiadi says.
One bright spot: The people who live on the island are predominately Muslim—which means unlike most of its kin worldwide, the warty pig doesn't end up as pork.
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