Oral fistulas in hihi (Notiomystis cincta): Are they genetic or acquired?

Authors: Low MR, Alley MR
Publication: New Zealand Veterinary Journal, Volume 55, Issue 1, pp 50, Feb 2007
Publisher: Taylor and Francis

Animal type: Avian, Wildlife
Subject Terms: Alimentary system/gastroenterology, Genetics, Oral/teeth
Article class: Abstract

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Abstract: Sublingual oral fistulas were found to occur in about 10% of adult hihi (or stitchbirds, Notiomystis cincta) examined on Tiritiri Matangi Island. All birds were the progeny of 40 individuals translocated from Little Barrier Island in 1996 but no fistulas were observed in the birds at the time of translocation. The earliest fistulas were observed in birds at about 1–2 years of age and took the form of small slits 1.5–6 mm in length parallel and adjacent to the lower mandible and usually located midway between the tip and base of the lower beak. In some birds, the tongue protruded intermittently through the fistula and this caused the defect to enlarge and eventually protrusion of the tongue became permanent. In older affected birds, the defect involved the whole of the ventral oral floor and protrusion of the tongue produced erosion of the ventral surface of the mandible. Small to moderate fistulas had no effect on body condition or productivity but severe fistulas with permanent deviation of the tongue affected nectar-feeding and in some cases reduced the female’s ability to successfully rear fledglings. Histopathology showed that the fistulas occurred in the thinnest region of the floor of the oral cavity near its attachment to the mandible. The discovery of an oral abscess in one bird at this site and the known ability of hihi to ingest large insects suggests that the defects may arise from injury to the floor of the oral cavity during feeding.

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