A Northern Giant Petrel photographed with a sublingual oral fistula sparks a request

A Northern Giant Petrel with a sublingual oral fistula, photograph by Helen Badenhorst, southern Indian Ocean, 27 January 2025

Dr James Reynolds (Assistant Professor in Ornithology and Animal Conservation, Centre for Ornithology, School of Biosciences, University of Birmingham, UK) has written to ACAP Latest News on a long-term citizen science project that he has been running about the incidents and causes of sublingual oral fistulas in the world's birds.  Since 2016 he has collated records of the condition in nearly 110 species of birds from all continents except Antarctica.  Many of the species in which oral fistulas have been recorded are gulls and terns.  James will be pleased to receive details of the condition in other seabird species.

James notes that a Northern Giant Petrel Macronectes halli was photographed by several participants on the Flock to Marion AGAIN! 2025 voyage in January this year, likely to be the same individual, as depicted on its Facebook Page.  He says “I am asking for help from people who routinely interact with free-living birds at close quarters when handling, observing and photographing them.  I am especially appealing to banders, wildlife photographers and birdwatchers to respond but I am happy to hear from anyone with relevant information.  All records of this rare condition are invaluable because they allow us to map the condition's occurrence onto location, and phylogenetic and ecological trait spaces.  The ultimate aim of the research project is to identify the cause(s) of this condition and thereby to ensure that we can protect avian biodiversity, and especially seabirds that face so many threats, against it proliferating.”

Records of ACAP-listed and other seabirds exhibiting sublingual oral fistulas can be sent to James at This email address is being protected from spambots. You need JavaScript enabled to view it..

Relevant publications:

Camiña, A. & Guerrero, L.M. 2013.  An Eurasian Griffon Gyps fulvus disadvantaged for feeding.  Vulture News 64: 66-68.

Castro, I. & Taylor, J. 2001.  Survival and reproductive success of Stitchbird (hihi, Notiomystis cincta) suffering from a bill abnormality (oral fistula).  Notornis 48: 241-244.

Hughes, B.J., Martin, G.R., Wearn, C.P. & Reynolds, S.J. 2013.  Sublingual fistula in a Masked Booby (Sula dactylatra) and possible role of ectoparasites in its etiology.  Journal of Wildlife Diseases 49: 455-457.

Reynolds, S.J. 2021.  A call for observations of birds with sublingual oral fistulas in central and eastern Europe, and beyond.  Ornis Hungarica 29: 188-194.

Reynolds, S.J., Martin, G.R., Wearn, C.P. & Hughes, B.J. 2009.  Sub-lingual oral fistulas in sooty terns (Onychoprion fuscata). Journal of Ornithology 150: 691-696.

Rintoul, D.A. & Reynolds, S.J. 2019.  Sublingual oral fistula in a Franklin’s Gull (Leucophaeus pipixcan).  Kansas Ornithological Society Bulletin 70: 53-56.

John Cooper, Emeritus Information Officer, Agreement on the Conservation of Albatrosses and Petrels, 28 July 2025