Abnormal molting, including partial or incomplete molt, arrested molt cycle, or inappropriate frequency of molt, is a primary concern for the managed African penguin (Spheniscus demersus) population and is documented across institutions.1,2 In order to identify risk factors for abnormal molts and characterize intervention opportunities, a comprehensive survey evaluating numerous husbandry and medical parameters was created. Results of this survey represent 45 African penguin holding facilities and 736 unique animals. Of those individuals, 135 (18.3%) demonstrated an abnormal molt over the 5-yr study period. Identified risk factors included advanced age and facilities utilizing freshwater pools. Normally molting penguins were more commonly housed with saltwater pool access and natural lighting cycles. Current treatment for inducing molt in African penguins, including hormonal regulation, dietary modification, and holistic interventions, is anecdotal and has been met with variable success. Subcutaneous 5.4 mg melatonin implants placed in anticipation of environmental molting cues showed the most promise at inducing catastrophic molt, with 14/17 (82.3%) of affected individuals molting normally following this treatment. Contrary to reports in other penguin species, thyroxine and progestin treatments were rarely associated with molting in the birds in this study.3-5 Survey analysis indicated that abnormal molt is a complex, multifactorial process, but modifiable factors exist that may predispose animals to abnormally molt. Addressing these factors in future exhibit designs may mitigate the prevalence of this condition. Despite these efforts, it is likely that medical interventions will be required to aid in the treatment of abnormal molting in this species.
The authors thank all institutions participating in the Association of Zoos and Aquariums African Penguin SSP for sharing the data represented throughout this manuscript. Specifically, the authors thank African Penguin SSP Coordinators Steve Sarro and Gayle Sirpenski for their assistance and encouragement throughout this project and Dr. Ellen Bronson for her assistance in the development of this project. The authors also thank the Saving Animals From Extinction program for their support of this species and its conservation.
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2. AZA Penguin Taxon Advisory Group. Penguin (Spheniscidae) Care Manual. Silver Spring, MD: Association of Zoos and Aquariums; 2014.
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5. Webster RKE, Aguilar RF, Argandona-Gonzalez AK, Conayne P, De Sousa D, Sriram A, Svensson CM, Gartrell BD. Forced molt in four juvenile yellow-eyed penguins (Megadyptes antipodes). J Wildl Dis. 2016;2:809–816.