Fourteen endangered Borneo pygmy elephants have recently been found dead in a Malaysian forest, presenting a mystery for wildlife officials and conservationists.

The recent deaths highlight the vulnerable status of the species, which now numbers about 1,500 animals. Scientists don't know how many pygmy elephants previously existed on the island, although it's likely the population wasn't much higher than it is today, said Barney Long, head of Asian species conservation at WWF-US.