Prognostic indicators for survival in African penguin chicks (Spheniscus demersus): A retrospective analysis.

ABSTRACT

Mystic Aquarium has successfully maintained an active breeding population of African penguins since 1990. Between 1990 and 2015, 477 eggs were laid, 84 of which were recommended for rearing according to the SSP Breeding and Transfer Plan. Sixty-five percent hatched successfully, and total fertility ranged from 56% to 78%. Of the 55 hatchlings, 60% of chicks reached fledgling age (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 were broken down into the following categories failure to thrive (in the absence of a definitive cause of death) (41%), respiratory disease (32%), parent-associated trauma (13%), congenital defects (9%), and gastrointestinal disease (5%). Analysis of associated factors identified a significant correlation between the hatch weights of chicks that survived beyond day 7 (60.5-66.0 g), and those that did not (49.5-59.5 g). Further positive correlations were established between chick hatch weight and both dam body weight, and egg weight. While hand-reared chicks gained weight more slowly than their parent-reared counterparts, results showed that rearing method had no significant impact on survival. The findings of this study provide a baseline for assessing reproductive success and chick mortality, and supply prognostic indicators for evaluating chick success in managed African penguin populations.