Pandas Need More Than Just Shoots and Leaves

Pandas eat bamboo. Duh, you say, that's something everyone knows. The giant fluff balls need bamboo forests to survive and to conserve the bears their bamboo needs to be conserved as well. Duh, you say again. Well, some new research suggests that it might not be that simple.

For years scientists have studied what they thought was suitable habitat for pandas — looking at forest cover, slope, elevation, and (usually) most importantly bamboo cover. The Chinese government has set up nature reserves throughout the country in habitats they considered suitable for the panda lifestyle — areas with plenty of bamboo. But a recent study found that while bamboo cover was important to pandas, the age of the forest was also crucial.

Researchers from the San Diego Zoo partnered with a team in China to look at data collected by the Chinese State Forestry Administration's Third National Survey — a project that sent teams throughout nineteen reserves in four different mountain ranges (some of the last remaining panda habitats) — to survey the giant panda's habitat use. These teams looked for signs of pandas — usually poop but sometimes foraging marks or sightings — and then recorded conditions like bamboo presence, forest age, tree diameter, forest age, altitude and slope.

When they looked at these different variables to see which ones best correlated with panda markers, two things stood out. The first was the presence of bamboo, which was obvious since that's the panda's food source. But just as important was the age of the forest. For some reason, pandas need these old, healthy forests just as much as they need the bamboo they eat.

The authors of the study offer a few possible explanations for why old growth forests might be so important for pandas. It could be that the bamboo growing in old growth forests is more nutritious, or that old growth forests provide better den sites for mother pandas. They don't know for sure.

Of course, pandas are still obligate bamboo specialists: Without bamboo to eat, they will die. And the life cycle of bamboo is one of the reasons these wildlife preserves are so important. Different species of bamboo flower, seed, and die at different intervals — entire stocks can be dead from a year to twenty in between cycles. When the pandas lived in their normal range this wasn't a problem, because when the species of bamboo common to where they lived died, they would simply go elsewhere where the bamboo was still growing. But now that humans left the bears with little slivers of forest to live in, they can't migrate when the bamboo in that area dies. Having a wildlife preserve with adequate diversity in bamboo species is still important.

But now wildlife managers have a new criterion to look for — old growth forest — which doesn't exactly make their job easier, especially since old forests are harder and harder to come by. Panda habitat in China is quickly thinning out, and even within the reserves there is rampant deforestation from illegal logging. Last year, the World Wildlife Fund pledged $6.39 million to expanding China's panda reserves, but the number of bears in the wild is still hovering around 2,500 adults.

Protecting the panda is, in some ways, disproportionately important to us. They're what are called "charismatic megafauna" — large animals that we think are cute and want to conserve more than their uglier compatriots. Losing the panda is something we simply will not stand for and will commit millions of dollars each year to fighting.

But this study also raises a bigger question: How much do we really know about the conservation needs of individual species? If we are still discovering what makes good habitat for the panda, a relatively well studied and well funded flagship species, what are the chances that we're getting it right for fin whales or Adelophryne maranguapensis, an endangered species of frog endemic to Brazil?

I don't know the answer to those questions, but hopefully with additional research, conservation, and preservation of a diverse array of landscapes, we can get it right somehow, even if it's by chance.