May 16 to 22, 2011, is Bear Awareness Week, and we hope you’ll join us in celebrating these amazing animals. Today we focus on giant pandas.
Unfortunately for the giant panda, human impact has caused major fragmentation of their habitat. Giant pandas in the Qionglai mountain range have suffered greatly; isolated fragments of their habitat contain very few individuals. Originally, giant pandas ranged through the lowlands of southern China, northern Vietnam, and northern Myanmar. They are solitary animals for a majority of the year, except during the breeding season, March to May. Each giant panda requires a great amount of habitat, and in some cases that can be up to 100 square miles (260 square kilometers).
Bamboo is their primary food source, and depending on the species of bamboo they will consume either its leaves or culm. Giant pandas require the consumption of bamboo for their internal organs to function correctly. As the bamboo passes through their intestinal tract, it cleans the mucus that lines the tract for protection from being punctured by the bamboo. If the mucus is not cleaned regularly, then the animal will become extremely ill and suffer other complications. The nutritional value of the bamboo is very low, resulting in the need for an adult giant panda to eat up to 50 pounds (23 kilograms) of bamboo a day. Fortunately, bamboo is the fastest growing plant on Earth and can grow up to 18 inches (46 centimeters) per day and reach heights over 100 feet (30 meters). The habitat that a giant panda lives in needs to contain multiple species of bamboo; when a species of bamboo flowers, all of it dies off at once. This process only happens every 30 to 60 years, but in the early 1980s, three species of bamboo flowered at the same time in the giant panda habitat, resulting in the loss of hundreds of wild pandas. As you can see, plentiful habitat is essential for these bears to successfully forage and get enough bamboo year after year.
Today, giant pandas are isolated to 24 populations that span 6 mountain ranges at the base of the Tibetan plateau. It has been shown that these isolated populations are increasing in size, but there are going to be long-term effects resulting from the lack of dispersal between these populations. Habitat between the reserves is not currently protected, and it is believed that approximately 40 percent of the giant panda population resides in these corridors. In the unprotected habitat, the landscape is constantly subjected to the development of roads, agriculture expansion, and fuelwood collection.
Now that giant pandas have been isolated to reserves, researchers have begun to look at how temporal changes will affect their habitat. In 2007, researchers performed a focused study on the Wolong Nature Reserve in Sichuan, China. The connectivity outside the reserve diminished between 1965 and 2001 due to the loss of giant panda habitat inside and outside of the reserve. Although there was a slight increase in connectivity between 1997 and 2001, it was not great enough to negate the current loss of habitat. Much of the loss was due to the collection of fuelwood. Over three decades (1970 to 2000) the people of China have begun to collect fuelwood from higher and higher elevations, collecting this resource in valuable giant panda habitat.
Natural disasters also have a large-scale impact on how a habitat may become fragmented. On May 12, 2008, the Wolong Nature Reserve suffered a 7.9-magnitude earthquake; it collapsed entire canyons by bringing down mountainsides and diverted rivers to alternate paths. There is great concern that between the natural disaster and extensive post-human activities of reconstruction, the Wolong Nature Reserve will become even more fragmented.
Overall, giant pandas have been greatly impacted by fragmentation through logging for fuelwood, agriculture needs, and an earthquake. These impacts are not going to resolve anytime soon, and long-term management of this endangered species is going to be a necessity. By expanding reserves in China, continuing long-term research, and educating the public with our developing knowledge of the giant panda’s needs, their future will continue to improve.
Jennifer Keating is a research scientist for the San Diego Zoo’s Institute for Conservation Research. Read her previous post, Sounds of Panda Breeding.
Update for bear lovers: Our brown bears will be receiving “snow” this weekend. Come watch them enjoy the cold stuff!