The 1,600 pandas left living in the wild face a new threat: Horses.
Seeking a safe investment, farmers in China's Sichuan Province have been increasingly buying up horses and allowing them to graze in the protected panda habitat of Wolong National Nature Reserve, new research finds. These horses clean out the bamboo groves that pandas rely on for food.
"It didn't take particular panda expertise to know that something was amiss when we'd come upon horse-affected bamboo patches," Vanessa Hull, a doctoral student at the Center for Systems Integration and Sustainability at Michigan State University, said in a statement. "They were in the middle of nowhere and it looked like someone had been in there with a lawn mower."
Logging has long threatened panda habitat, and conservationists have focused on limiting forest cutting to save the black-and-white bear. But Hull and her colleagues noticed, increasingly, that bamboo was vanishing from protected areas.
The researchers talked to local farmers and found that they'd heard from farmers in other areas that horses were, to mix livestock metaphors, veritable cash-cows. Horses are banned from grazing in cattle areas, so farmers would set them free in the Wolong preserve and round them up to sell when they needed quick cash. Between 1998 and 2008, the number of horses in Wolong rose from 25 to 350.
These 350 horses live in perhaps 30 herds. Hull and her colleagues approached four herds and fitted one horse in each with a GPS collar. They found that the horses' range overlaps with the pandas, and that both animals are drawn to the same sunny slopes and bamboo patches. But while a single horse and a single panda eat about the same amount of bamboo each, 20 horses descending on a patch at once cleans out the buffet, leaving little for solitary pandas that come later.
"Livestock affect most of the world's biodiversity hotspots," Jianguo "Jack" Liu, a human-environment scientist at Michigan State, said in a statement. "They make up 20 percent of all of the Earth's land mammals and therefore monopolize key resources needed to maintain the Earth's fragile ecosystems."
The findings, published in the Journal for Nature Conservation this week, have made a difference, however. When Liu, Hull and their colleagues presented the results to Wolong Nature Reserve officials, they banned horses from the reserve.