We have received a request from Dr Jim Reynolds of the Centre for Ornithology at the University of Birmingham for any information ringers may have concerning sublingual oral fistulas in wild birds. This condition has been considered a rare one and involves an abnormality where the skin and muscle of the lower mandible is missing, and the tongue protrudes through this opening, often remaining there permanently.
Jim is embarking on a study of this condition (attempting to determine its prevalence across all bird species), which he documented a few years ago in two seabird species (Sooty Tern and Masked Booby) on Ascension Island. Apart from these species, oral fistulas have only been described in two other species, first in the 'Vulnerable' Stitchbird and later in Eurasian Griffon Vultures.
Jim asks that if you have ever encountered a bird with an oral fistula, to complete a Reporting Form with as much information as possible, and send this to him with any pictures you may have. See this Information Sheet which contains more info about the condition, and download this Reporting Sheet which you can fill in and return by email to Jim (email address on the form).
You can also use this link provided by the University of Birmingham to access all the information and forms.