A call for observations of birds with sublingual oral fistulas in central and eastern Europe, and beyond

Abstract Birds with major physical abnormalities do not live for extended periods and, therefore, are rarely observed in the wild. This is particularly the case for birds with defects in their feeding apparatus that succumb to mortality rapidly through precipitous declines in their foraging efficiency and body condition. Sublingual oral fistulas are such an abnormality and involve the development of an opening (or fistula) in the floor of the oral cavity through which the tongue extends, resulting in its permanent exclusion from the mouth. The tongue dehydrates and dies. First described in the 2000s in Stitchbirds (Notiomystis cincta) in New Zealand, it has rarely been reported in other species. However, following our recent discovery of two seabird species on Ascension Island in the South Atlantic displaying oral fistulas, in 2016 I launched a citizen science research project requesting reports of birds with the condition in the world’s avifauna. To date, I have received 188 reports of birds of 82 different species with many contributed from western Europe. However, with only one report from central and eastern Europe, I am now requesting the assistance of birders in the region and in other parts of the world to contribute to this ongoing research project.