Surgical Correction and Use of Prosthesis for Bill Malalignment in Yellow-Eyed Penguin Chicks (Megadyptes antipodes)
Yellow-eyed penguins (Megadyptes antipodes) are an endangered species endemic to New Zealand and its sub-Antarctic islands. They are found on the south-eastern coast of the South Island, Stewart Island and its offshore islands, Auckland Islands and Campbell Islands with current estimates of approximately 2000 breeding pairs. Over the past 30 years there have been recurrent mass mortality events affecting either adults or chicks1-3 and a number of poor breeding seasons that have threatened the population. In the 2008/09 breeding season there was a high incidence of egg and chick death in the mainland population on the Otago Peninsula. Eight chicks from Okia Reserve on the peninsula were found with severe craniofacial deformities, and six of these were euthanised on the grounds that they would not be able to survive in the wild. An extensive investigation examining possible genetic, heat stress and toxic aetiologies was conducted, but the cause of the deformities could not be identified.3 An unidentified environmental teratogen was suspected to be the cause. During the current 2013/14 breeding season, three chicks from the same reserve were found with mild craniofacial deformities. The deformities were characterised by abnormalities of the skull and jaws that resulted in a lateral displacement of the lower bill creating a scissor-beak conformation and an overshot lower bill. Radiographs and computed tomography (CT) scans were performed to assess the degree of boney involvement. Surgical correction of the abnormal bills was attempted. The distal tip of the lower bill was removed with either pliers or a Dremel power tool. In all three cases only 2–5 mm of keratin needed to be removed to allow occlusion of the upper and lower bills. Nail acrylic was applied to the cut surface for protection. A prosthesis made from epoxy putty (Selleys Knead-IT®) was attached to the upper bill to form a ramp which guided the lower beak medially into the correct position when closed. The birds were reassessed every four weeks and a new prosthesis placed. The results of the corrective surgeries and prostheses will be presented.
The authors wish to thank Mel Young from the Department of Conservation. The authors would like to thank Pauline Conayne, Carina Svensson and Deneka De Sousa, the veterinary technicians involved with husbandry and care of the chicks during their stay in the hospital.
* Presenting author
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