Located in northwestern Yunnan Province in southwestern China, the Gaoligong Mountains harbor rich bird diversity with 796 species, of which 14 are parasitic cuckoos. Yet, avian nest parasitism by cuckoos in this biodiversity hotspot has rarely been documented. On May 12, 2022, we encountered a parasitized nest on the bank of a trail in the broadleaf forest at an altitude of 2 202 m in the Baihualing region of the Gaoligong Mountains (Fig. 1 and 2). Through field observations combined with infrared camera monitoring, we confirmed the host species and the fate of the nest, and monitored the feeding behavior from May 14 to 21. We counted feeding frequency in every 2 h on each monitoring day. To assess how feeding frequency changed with nestling age, we used a generalized linear mixed model (GLMM) with Poisson distribution, with feeding frequency as the response variable and nestling age as the predictor. We also used kernel density estimation (KDE) to explore how feeding frequency changed through time of day. Finally, we extracted DNA samples from nestling feathers to identify the species of brood parasite. The host species was the Streak-breasted Scimitar Babbler Pomatorhinus ruficollis, a common babbler species in the Gaoligong Mountains with a broad elevation from 1 000﹣2 800 m. Molecular evidence confirmed the parasite as the Large Hawk Cuckoo Hierococcyx sparverioides (breeding elevational range:700﹣2 500 m in the Gaoligong Mountains), with a high overlap of elevational range with the host species. We recorded a total of 298 feeding events, and GLMM suggested that feeding frequency increased with increasing nestling age (Fig. 3a). KDE identified three feeding peaks (from 8:00 to 10:00, from 14:00 to 16:00, and from 18:00 to 20:00) during the day (Fig. 3b). The nest failed due to depredation on May 22, 2022. The predator was identified as the Leopard Cat Prionailurus bengalensis. Through a literature review, we confirmed that this is the first record of brood parasitism on the Streak-breasted Scimitar Babbler by the Large Hawk Cuckoo. Future research on brood parasitism in this montane biodiversity hotspot would be helpful in understanding the role of this biotic interaction in shaping the elevational distributions of both hosts and parasitic cuckoos.