The study of diet and trophic relationships is an important aspect in understanding the ecology and life history of many organisms and ecosystems. Along the Andes, forests dominated by the genus Polylepis (Rosaceae), have a high diversity of specialist and threatened birds depending on them, as well as a variety of associated species. However, the composition and seasonal variation in the diet of most of these species are unknown. In this study, we described both patterns for three specialist bird species in Polylepis forests: the Giant Conebill (Conirostrum binghami), the Tamarugo Conebill (C. tamarugense) and the Thick-billed Siskin (Spinus crassirostris), as well as for three others commonly associated with them: the Buff-breasted Earthcreeper (Upucerthia validirostris), the Creamy-breasted Canastero (Asthenes dorbignyi), and the Black-hooded Sierra-Finch (Phrygilus atriceps), in the department of Arequipa, southwestern Peru. After analyzing the stomach content of these species during the humid and dry seasons of 2017, we found that the diet of the specialist birds was composed mainly of arthropods for C. binghami and C. tamarugense, and seeds for S. crassirostris. Within the arthropods, insects (Coleoptera, Hemiptera and Hymenoptera) represented almost the entire diet, while arachnids represented only a small portion. The diet of the associated birds was also composed mainly of arthropods (insects, spiders and scorpions), in the case of U. validirostris and A. dorbignyi, while P. atriceps consumed mainly seeds.