Date of Award
An important life history event for African penguins is the annual molt, which restores healthy plumage for proper thermoregulation and waterproofing. This study examined three, not necessarily mutually exclusive, hypotheses to explain the etiology of improper molting in zoo and aquarium populations: (1) the syndrome is hereditary; (2) birds do not amass enough nutritional resources prior to the molt to allow the molt to progress normally; (3) the timing of the molt is disrupted by exogenous cues that are contrary to those experienced in the wild. A two-part survey was completed by 17 U.S. zoos and aquaria that returned information on individual birds and colony management. Abnormal molters represented 14.0% in 2012 and 13.5% in 2013 of the pooled population of African penguins held at respondent institutions. Sex, along with number of eggs laid within six months prior to molt, prevalence of sires or dams molting abnormally, or colony management practices did not have significant effects on the prevalence of abnormal molting. Normally molting birds gained significantly more weight prior to molt than did birds which molted abnormally. Additionally, birds that molted abnormally were significantly older than those which molted normally. It is thus hypothesized that as birds age, they are unable to maintain effective concentrations of hormones, in particular T3 and T4, which in turn affects pre-molt weight gain and therefore results in an abnormal molt. Uncovering the etiologies behind abnormal molting helps humans support both wild and zoo and aquarium based populations. It is suggested that further research be conducted on the cause(s) of low pre-molt weight gain and if hormone concentration and maintenance may be a factor in abnormal molts.
Austin, Carah, "Etiological study of molt abnormalities in the African penguin, Spheniscus demersus" (2016). Undergraduate Honors Thesis Collection. 325.