Functional Anatomy Of Mandibular Papillae In The Roseate Spoonbill

Abstract

The functional significance of mandibular papillae in feeding Roseate Spoonbills was studied. Feeding behavior of this species was investigated through observation both in the wild and under captive conditions. Spoonbills fed primarily by submerging the bill about half it's length and sweeping the head from side to side as they walked through the water. A non-visual means of prey location was employed. These observations suggested the presence of sensory structures on the bill itself. It was discovered during the study that mandibular papillae do not appear in spoonbills prior to maturation. In addition, all attempts to collect a mature bird were unsuccessful. An anatomical investigation of tissues from the maxilla of an immature spoonbill was made to determine the presence of any key structures which might reveal the nature of the papillae. Sensory corpuscles similar to those of Merkel or Grandry were discovered in the middle region of the maxilla. These findings represent the first direct evidence of sensory corpuscles in the bill of a wild ciconiiform bird. Although the mandibular papillae were never directly examined anatomically, the evidence derived from this research strongly indicates that the bill of the Roseate Spoonbill is a highly sensitive tactile organ. The significance of varied bill morphologies and feeding behaviors among members of the Order Ciconiiformes is discussed.