Caching faeces of other species: evidence of heterospecific coprophagy by Collared Pika (Ochotona collaris)?

Some species collect and consume the faeces of other species. However, evidence of such heterospecific coprophagy is rarely documented for wild mammals and has not been reported for Collared Pika (Ochotona collaris). We observed 14 Collared Pika haypiles (food caches) in northwestern Canada that contained faecal pellets of Hoary Marmot (Marmota caligata). Our observations were from two study areas ~700 km apart, suggesting that this behaviour may be widespread. We did not observe Collared Pikas consuming Hoary Marmot pellets, and they may collect them for other, unknown reasons, including as curios. Regardless, our observations are of value because they represent evidence of possible heterospecific coprophagy in Collared Pikas, which can potentially contribute to our understanding of their nutritional strategy.