In this study, we reported a case of insect‐plant‐bird interactions under climate warming. With a succession of warmer winters from 2013 to 2015, successive outbreaks of the moth Pantana phyllostachysae, a common defoliator for most bamboo species, occurred in the Wawushan Nature Reserve of Southwest China, leading to a rapid altitudinal range expansion from 1650 to 2050 m in P. phyllostachysae. The bamboo Chimonobambusa szechuanensis that is largely distributed at moderate altitudes consequently suffered much loss. Accumulated infested area of C. szechuanensis within the reserve during the 3 years covered ~90% of the suitable breeding habitats of Emei Shan Liocichla Liocichla omeiensis, a threatened songbird preferring to nest in the bamboo, which led to diversified nesting‐plant selection and a significant reduction in nesting success of the babbler. Our findings provide new evidence of the plasticity of avian breeding behavior, and of the impact of climate change on ecological communities through multi‐species interactions. The study has important conservation implications. [ABSTRACT FROM AUTHOR]