A pika is not a rodent. It belongs to the order Lagomorpha with rabbits and hares, and shares their two-pass digestion, re-ingesting soft caecal pellets to extract nutrients from harsh alpine vegetation.
The haypile is the species' defining behaviour. Across the short mountain summer a pika makes repeated trips carrying mouthfuls of forbs, grasses and sometimes toxic plants whose compounds act as preservatives, spreading them under an overhanging rock to cure before storage. A finished pile can weigh several kilograms and represents the whole winter food budget, since pikas stay active beneath the snowpack.
The animal's real vulnerability is heat, not cold. Pikas have a high resting body temperature and poor tolerance of warmth, and have been reported to die after only a few hours of exposure to temperatures around 25 degrees Celsius. Some low-elevation populations in the Great Basin have disappeared. The species overall is still assessed as Least Concern, so the accurate framing is local extirpation and range contraction rather than imminent global loss.