King penguins in zoos: relating breeding success to husbandry practices.
Journal of Zoo and Aquarium Research 4(2): 91-98
As global climate change warms the Southern Ocean, wild king penguins (Aptenodytes patagonicus) may face drastic population declines in the future. Moreover, the captive breeding programme in Europe is currently unsustainable and it is thus imperative to determine what is required for the successful breeding of king penguins. A questionnaire was used to assess the husbandry practices and breeding success of 12 American and European zoos. Overall, a positive relationship was found between yearly egg productivity and density of king penguins held in enclosures in different zoos. All zoos examined showed male-biased adult sex ratios. Yearly egg productivity was negatively related to the deviation from an even sex ratio. Mean hatching success was greater in zoos performing outside walks with king penguins than in those that did not. Based on records over 40 years, the population of the sustainably breeding Basel Zoo in Switzerland was modelled using stage-based matrix models to gain an insight into its breeding success. Years of medium colony size (density of 0.25 to 0.38 individuals per m2) displayed a larger growth rate than years with high or low colony size, and years with equal sex ratios showed a higher growth rate than those with male-biased or female-biased sex ratios. The results suggest zoological institutions should focus on increasing density and strive toward equal sex ratios within king penguin populations to maximise breeding success. Where possible, adding outside walks should also be taken into consideration.