Survival Status

The past and present habitat of the giant panda

Fossil remains of giant panda are scattered widely throughout China, showing its successful colonization of the vast area. Its evolution is a mystery. It appears suddenly in fossil records about three million years ago (Early Pleistocene) with no clear-cut ancestors. Altogether, evidence of giant panda occupation has been found at forty-eight sites in fourteen provinces in China, from Sichuan westward almost to Shanghai, and from southern Yunnan to as far north as Beijing. Fossil remains have also been discovered in northern Vietnam as far south as Vinh and in one location in Burma. Almost all the sites date from the Pleistocene era, evidence of the species’ far wider distribution during this epoch than is the case now. This may have been partly due to a climate that was more favourable to the giant panda. It was warmer and wetter in those days, and bamboo are thought to have expanded their range during such meteorological golden periods, and to have been forced to contact their range to mountain refuges when cooler and drier conditions prevailed, as they did during the late Pleistocene and the Holocene Period. But while some of the decrease in panda distribution may very well have been due to climatic changes, and population crash that occurred cannot be only blamed on ‘natural causes’.

As for almost all other endangered animals, main threat to the survival of the giant pandas is the destruction of its habitat. (see People-related Threats). Between 1974 and 1976 the first intensive survey to determine the status of the giant panda in the wild, and estimated that there were just around 1000 animals remained.

In biological systems there is a lower limit of population, the Minimum Viable Population (MVP), below which there is very little probability of a population surviving long-term. It is generally accepted that most species required at least 500 individuals to ensure their long-term viability and avoid the sometimes disastrous effects of inbreeding and random genetic movement. In geneticist’s terms inbreeding results in more individuals who are homozygous for recessive deleterious genes, which basically means that hidden harmful characteristics show up more frequently in inbred populations, resulting in a loss of vigour, fertility, or both. There is also evidence that inbreeding can have a harmful effect on both the size of the litter and the survival of the young after birth. With the giant panda’s population standing at around 1000 and a MVP lower limit of 500, the species appears, at first sight, to be well within the MVP safety limits. Sadly, this optimistic assessment ignores new information on the degree of fragmentation of giant panda populations. The giant panda is already divided into six major populations, with very little chance of physically communicating (and therefore breeding) with one another. Most of these populations number less than fifty individuals and many as few as ten or less. Even within reserves, the populations are often fragmented and cut off from each other. This is indeed a bad news: a second rule of thumb in population genetics is that even short-term survival requires populations of at least fifty individuals.

One example will stand to demonstrate the disaster facing the species. The largest single area of remaining panda habitat is the Min mountain area (13300km square). Panda numbers in the Minshan are higher –between 210 and 280 animal –than in any other area. So, on the surface there is a large panda area with the greatest number of living pandas. Even so, with less than 500 individuals in the entire population, the long-term viability of the Minshan pandas must remain in doubt. And a closer look at the distribution of forest and pandas reveals an even more depressing prognosis. The Minshan pandas are broken up onto at least six separate groups. Some are tiny, numbering ten animals or less, with almost zero probability of even one animal crossing over the barriers between the different panda groups to ‘outbreed’.

This picture is repeated in every major panda reserve. Given such miserably small numbers in each population island, the prospects are bleak indeed. On this basis, most giant panda populations can be written off right now –unless Man steps in to ensure genetic interchange between populations, perhaps in the form of translocation of pandas from one area to another. Without action to redress the balance, the small size of most panda groups already marks them from extinction.