Bird-related hypersensitivity pneumonitis (BRHP) is a significant subtype of hypersensitivity pneumonitis, often progressing to a fibrotic form. Initially termed “bird fancier’s lung” (BFL), the condition was first reported in the 1960s among pigeon and parrot breeders. In Japan, BRHP is the second most common antigenic cause of hypersensitivity pneumonitis and the leading cause of fibrotic hypersensitivity pneumonitis. Avian antigens, particularly from pigeons, doves, and Psittaciformes, are implicated. Exposure occurs not only through bird breeding but also from environmental sources, such as nesting birds in urban settings and avian-derived household products. BRHP is divided into non-fibrotic hypersensitivity pneumonitis, including acute and subacute forms, and fibrotic hypersensitivity pneumonitis. Tests that are useful for diagnosis include serological tests for avian-specific IgG antibodies, lymphocyte stimulation tests, and inhalation provocation tests, though sensitivity varies. The ImmunoCAP® method, available since 2020, has improved diagnostic accuracy. Antigen avoidance remains the primary management strategy, yet disease progression often necessitates pharmacotherapy. Notably, BRHP has a higher risk of fibrotic progression compared to other hypersensitivity pneumonitis subtypes, with five-year survival rates between 30% and 60%. Given the clinical overlap between BRHP and idiopathic interstitial pneumonias, it is important to assess antigen exposure. Identifying avian antigen exposure through thorough patient history-taking is essential to improving prognosis. Increased awareness and early intervention can help mitigate disease progression and optimize patient outcomes.