Mystic Aquarium has successfully maintained an active breeding population of African penguins since 1990 during which time the population of breeding pairs has been increased from 2 to 12 pairs. Between 1990 and 2015 approximately 477 eggs were laid, 84 of which were incubated according to SSP guidelines. Of those, 66% hatched successfully, though data recorded between 1990 and 2011 does not differentiate between fertilized and unfertilized eggs. Data from 2012–2015 indicates that the likelihood of an egg being fertile ranged from 56 to 78%, with no discernable pattern between eggs laid from December to January and those laid in the "off-season." Of 55 successful hatchings, 60% reached fledgling age (approximately 80 days). Of the 22 chicks that died before fledging, 59% died within 7 days of hatching, and 82% within 30 days of hatching. Categories of mortality included: respiratory disease (31.8%), gastrointestinal disease (9.1%), trauma (13.6%), congenital (4.5%), or could not be determined (40.9%). Further analysis determined significant associations between the hatch weights of chicks that died within the first week (49.5–59.5 g) and those surviving beyond (60.5–66.0 g). A positive correlation was established between the body weight of the dam prior to laying and chick hatch weight. In comparing rearing methods, hand-reared chicks gained weight slower than their parent-reared counterparts; however, there was no statistically significant effect of rearing method on survival. The findings of this study provide a baseline for assessing reproductive success and chick mortality in African penguins maintained in zoo and aquarium collections.
The authors wish to thank the penguin husbandry staff at Mystic Aquarium and Dr. Paul Anderson for his assistance with statistical analysis.
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