 The red @-@ billed chough 's food consists largely of insects , spiders and other invertebrates taken from the ground , with ants probably being the most significant item . The Central Asian subspecies P. p. centralis will perch on the backs of wild or domesticated mammals to feed on parasites . Although invertebrates make up most of the chough 's diet , it will eat vegetable matter including fallen grain , and in the Himalayas has been reported as damaging barley crops by breaking off the ripening heads to extract the corn . In the Himalayas , they form large flocks in winter . 
