High-altitude engineers
In the Bayan Kara Mountains, a range that separates the great drainage basins of the Yellow and Yangtze rivers, lies the Sanjiangyuan National Park. This park, with an average elevation over 4,700 meters, is a vast area of alpine meadows and wetlands. Here, a small, unassuming mammal, the Plateau Pika (Ochotona curzoniae), shapes the entire ecosystem. Often living at altitudes between 3,100 and 5,000 meters, these relatives of rabbits are keystone species.
For decades, pikas were viewed as pests, blamed for rangeland degradation, and subjected to widespread poisoning campaigns that began in 1958. Scientific studies now show a different picture. Pika burrowing activity aerates the ground and increases water infiltration, which can reduce overland flow and minimize soil erosion. Their digging creates patches of bare soil that, while seemingly destructive, actually increase plant biodiversity. These disturbed areas provide new ground for different plant species to colonize, leading to a total species richness 1.3 to 2.5 times higher than in undisturbed patches. The pikas' burrowing transfers between 1 and 5 tons of soil per hectare to the surface, mixing soil layers and affecting nutrient cycles.
A foundation for life
The physical changes pikas make to the landscape directly support a wide array of other animals. In the largely treeless high-altitude meadows, pika burrows are shelters. Several species of birds, including the White-rumped Snowfinch (Onychostruthus taczanowskii), Rufous-necked Snowfinch (Montifringilla ruficollis), and Hume's Ground Tit (Pseudopodoces humilis), use abandoned pika burrows for nesting. This relationship can be symbiotic; snowfinches sometimes act as sentinels, giving warning calls at the approach of a predator, which benefits the pikas.
Plateau Pikas are a food source, especially because they do not hibernate and remain active all winter. They are the primary prey for an entire suite of predators, including the Tibetan Fox (Vulpes ferrilata), Upland Buzzard (Buteo hemilasius), and Brown Bear (Ursus arctos pruinosus). The ecological stability of this high-altitude environment depends heavily on the presence of healthy pika populations. Conservation efforts within the 190,700-square-kilometer Sanjiangyuan National Park now recognize the pika's importance, offering protection to this important ecosystem engineer.