Like other lagomorphs, pikas reingest fecal matter which is high in protein content and energy value (5.2 kcal/g). The plant food stored in haypiles is low in caloric content (4.5 kcal/g) but some populations utilize energy—rich aspen bark (5.2 kcal/g) during the winter and spring months. The daily energy intake of a non—gravid, non—lactating, adult pika (171 g) is estimated at 54.8 kcal of which 68% is assimilated. Food intake, and perhaps feces reingestion, is increased during pregnancy and lactation.