Pandas in peril
Pandas are highly sensitive to the scales of their habitats, and some regions earmarked for conservation are individually too small to support the animals sustainably, new research suggests.
Conservationists estimate that there are about 2000 pandas left in the wild, all of them inhabiting a tiny area in the mountains of south central China's Sichuan, Shaanxi and Gansu provinces.
Once their range extended as far afield as Myanmar and Vietnam, but human encroachment means that now only a small isolated pocket remains to sustain the animals. Determined international efforts are being made to save the panda and these have been quite successful with numbers doubling since the 1980s.
But a study published in the journal Scientific Reports this week by China West Normal University scientist Jing Qing and his colleagues suggests that this could still prove fruitless if more attention is not paid to the issue of space.
The Chinese team have used the latest data available covering 5 existing giant panda habitat regions and accounting for nearly 80% of the total habitat available, to calculate the minimum area requirements (MAR) for the panda.
The MAR is the amount of physical habitat required to sustain a population of a given species. This varies because some animals are more area-sensitive than others and need extra space to fall back on when adversity strikes, like variations in climate, food abundance, slow reproductive rates or disease.
Qing's team divided up the Panda range into over 5000 suitable habitat "patches" and then compared how the relative sizes of these patches affected the likelihood of Pandas living there. The results suggest that pandas are strongly area-sensitive and have a MAR of at least 114.7 square kilometres per population.
Encouragingly, many of the regions set aside for Pandas are sufficiently large to sustain viable populations, and the team have been able to highlight some areas that could be linked by "corridors" to enable animals to move between them to achieve the required threshold sizes to support the animals. More worryingly, one region in the south, in the Xiaoxiangling Mountains, is so fragmented by human incursion that the largest contiguous habitat patch measures just 81.7 square kilometres.
In keeping with the team's results, this is the area with the smallest and most endangered panda population. Previously animals reared in captivity have been reintroduced into this region to prop of numbers, but, as the Chinese team point out, their findings show that this is not a sustainable solution. Instead, they emphasise that efforts need to focus on increasing the habitat patch size so small patches are consolidated into something approaching the MAR.