Congenital deficiency of a tracheal ring in a Eurasian sparrowhawk (Accipiter nisus): a micro-computed tomography case report

Background Congenital tracheal developmental disorders in birds are rarely reported in veterinary literature and may be underdetected in wild populations due to limited diagnostic and post-mortem investigations. Such anomalies may affect individual fitness, rehabilitation outcomes, and survival, with potential implications for population-level assessments. Case presentation We report a congenital absence of a tracheal ring in a Eurasian sparrowhawk (Accipiter nisus). The specimen was examined using non-destructive high-resolution micro-computed tomography (micro-CT) with a spatial resolution of 0.048 mm. Imaging revealed the absence of the 45th tracheal ring without evidence of additional skeletal abnormalities. Results The identified anomaly may be associated with clinical manifestations consistent with tracheal instability, including respiratory stridor, abnormal respiratory sounds, coughing, wheezing, and altered vocalisation. Given the role of vocal communication in territorial behaviour and reproduction, such structural abnormalities may have functional and ecological consequences. Conclusions This report demonstrates that congenital tracheal anomalies can occur in wild raptor species and may remain undetected without advanced imaging techniques. The application of high-resolution micro-CT provides a valuable tool for identifying subtle anatomical abnormalities and may contribute to improved diagnostics, rehabilitation strategies, and population health assessments in wildlife species. To the best of our knowledge, this is the first report describing congenital absence of a tracheal ring in a wild bird using micro-CT.