Animal poop may seem inconsequential but it supplies scientists with precious information: from a tiger’s identity to elephant stress levels. Most recently, faeces of Royle’s pika – a small rabbit-like mammal found in India's Himalaya – reveal that these animals survive almost entirely on specific plants that grow only in cold, wet conditions; plants that are not expected to tolerate the warmer weather that climate change would bring.
Warmer weather can alter plant communities in high-altitude ecosystems like the Himalaya and also affect animals that depend on them. For instance, fossil records reveal that cold-loving pikas dwelt in parts of then-frigid Africa, too. However, warmer weather around 5-10 million years ago reduced the ‘C3’ plants (ancient plants that use more water during photosynthesis and can survive only in cold and wet climes) that the pikas ate, leading to the animals’ extinction.
In such times, unravelling animal diets is crucial, and researchers at Bengaluru’s Indian Insitute of Science and the University of Sheffield deciphered the plant families that the Royle’s pika – which prefers rocky areas, especially tali (piles of rock that accumulate at mountain bases) – eats. They collected 172 pika faeces (pellets) from five locations in Uttarakhand including the Nandadevi Biosphere Reserve. In the laboratory, they used a method known as DNA ‘metabarcoding’, which helps identify the DNA of plant species in animal faeces.
Pellet facts
The researchers found that the pellets contained 79 different genera of plants (earlier, visual observations of animals feeding had revealed only 26 species); 97% of these are C3 plants that cannot tolerate hot and dry weather. The results, published in Molecular Ecology, also reveal that the pikas prefer forbs (flowering herbs) over grasses; more than 50% of plants they eat are endemic to the Himalayas. Interestingly, the team also find that characteristics of a talus can influence plant diversity; a larger talus increased plant species, offering pikas a more diverse diet. “A talus with deeper and wider crevices permits easy access for predators,” said Bhattacharyya. “We found that pikas dwelling in such areas had a lower diversity of plants in their diets since predation risks made them more cautious.”
Currently, there is no dearth of C3 plants available for the pikas that are distributed widely between 2,400-5,000 metres in the Himalaya. However, pikas could be affected if climate change reduces the distribution of C3 plants that the mammals feed almost entirely on, write the authors.
