Gross anatomical features of the air sacs of the common kingfisher (Alcedo atthis)

This research was conducted with the main aim to investigate the morphology of air sacs system in kingfisher. Eight healthy, adult kingfishers were used to explore the morphological characteristics of the air sacs, which were examined grossly and with latex and cast preparations. In general, the morphological features of the kingfisher air sacs are similar to other avian species. We observed nine air sacs; four paired sacs (cervical, cranial thoracic, caudal thoracic and abdominal air sacs) and one unpaired sac; the clavicular air sac. The cervical air sac communicated to the lung by the medioventral bronchus and gave off intermuscular, subscapular and subcutaneous diverticula. The clavicular air sac communicated with bronchial tree through the medioventral bronchus and had subscapular, axillary, humeral, subpectoral and sternal diverticula. The cranial and caudal thoracic air sacs were communicated with the lung through the lateroventral bronchi. Each cranial thoracic air sac gives diverticulum which fused medially forming one large diverticulum; while, there were no diverticula extending from the caudal thoracic air sacs. The left abdominal sac was the largest air sac. The right and left abdominal sacs gave off branches to diverticula that pneumatized synsacrum. The abdominal air sacs gave off femoral diverticula caudal to the hip joint in addition to the perirenal diverticula. In conclusion, the present study provided detailed and comprehensive data about the morphology of air sacs system in kingfisher. In general, the air sacs of kingfisher are almost similar to other bird species with few variations. These findings could be enhancing anatomical knowledge of respiratory system of kingfisher bird.